FarmHub

Small-scale Fisheries Background

Sat, 22 May 2021 00:00:00 +0000

Small-scale fisheries, encompassing all activities along the value chain in both marine and inland waters, play an essential role in food security and nutrition. According to estimates, small-scale fisheries employ more than 90 percent of the approximately 120 million people employed in fisheries. An estimated 97 percent of these fishworkers live in developing countries. In addition, about half of those working in small-scale fisheries are women, mostly engaged in post-harvest activities, especially marketing and processing. Small-scale fisheries are increasingly being recognized, especially in developing countries, for their contribution to sustainable food systems and the opportunities they present for sustainable development and poverty eradication (World Bank, 2012).

Chapter 7 of the SSF Guidelines: Value Chains, Post-harvest and Trade

Sat, 22 May 2021 00:00:00 +0000

Chapter 7 of the SSF Guidelines is dedicated to value chains, post-harvest operations and trade. In particular, it recognizes the rights of fishers and fishworkers, acting both individually and collectively, to improve their livelihoods through trade at global, regional and national levels, and by enhancing value chains and post-harvest operations.

The recommendations contained in Chapter 7 include building capacity of small-scale fishers, strengthening organizations and empowering women; reducing post- harvest losses and adding value to small-scale fisheries production; and facilitating sustainable trade and equitable market access. The following subsections present key challenges faced by small-scale fishers and fishworkers in obtaining market access and enhancing value chains and post-harvest operations, and highlight potential solutions based on recommendations in the SSF Guidelines.

Overview of the Small-scale Fisheries Case Studies

Sat, 22 May 2021 00:00:00 +0000

The case studies presented in this document were selected by the FAO Small-Scale Fisheries Task Force through a competitive selection process. Case studies were selected based on the perceived replicability of initiatives by relevant actors, including national administrations, NGOs, CSOs, private enterprises, development agencies, intergovernmental bodies, and others. To facilitate this universal applicability, it was important to ensure geographic diversity and broad coverage of the recommendations in Chapter 7 of the SSF Guidelines.

Small-scale Fisheries Guidelines Discussion

Sat, 22 May 2021 00:00:00 +0000

Since the endorsement of the SSF Guidelines by COFI in 2014, recognition of the importance of small-scale fisheries has increased, as has awareness of the recommendations contained in the Guidelines. These are now reflected in various regional and national policies and strategies. Moreover, as demonstrated by the case studies presented here, the principles and provisions of the SSF Guideline are being applied by a broad range of actors and in diverse contexts.

Small-scale Fisheries Conclusions

Sat, 22 May 2021 00:00:00 +0000

Small-scale fisheries actors engage in global, regional and national value chains, but face challenges in securing market access and a fair distribution of the resulting benefits. Fisheries value chains are part of broader food systems. These food systems encompass all aspects of – and activities related to – food production, processing, distribution, sale and consumption, as well as their socio-economic and environmental impacts (HLPE, 2017). In a food system, factors such as climate, environment, infrastructure and institutions are linked to the value chain. For this reason, developing and improving value chains requires a comprehensive approach.

The Central Fish Processors Association: Collective action by women in the Barbados flyingfish fishery

Sat, 22 May 2021 00:00:00 +0000

Maria Pena Janice Cumberbatch Patrick McConney Neetha Selliah Centre for Resource Management and Environmental Studies (CERMES), Barbados

Bertha Simmons Independent consultant

Women are prominent in the post-harvest segment of the flyingfish value chain in Barbados, but this is not reflected in their participation in fisherfolk organizations. The Central Fish Processors Association (CFPA) offers a unique example of an organization that currently comprises only women and has been woman-led from its inception. Unable to individually voice their concerns about working spaces at the fish market, the women formed the only fisheries post-harvest association in Barbados. This case study analyses the process of formation of the CFPA, its development and the benefits it has provided to its members in terms of their livelihoods and domestic lives, as well as to the flyingfish fishery more generally. Although challenges persist, it illustrates existing and emerging good practices consistent with the principles of the Voluntary Guidelines for Securing Sustainable Small-Scale Fisheries in the Context of Food Security and Poverty Eradication.

Introduction to recirculation aquaculture

Wed, 15 Jul 2020 00:00:00 +0000

Recirculation aquaculture is essentially a technology for farming fish or other aquatic organisms by reusing the water in the production. The technology is based on the use of mechanical and biological filters, and the method can in principle be used for any species grown in aquaculture such as fish, shrimps, clams, etc. Recirculation technology is however primarily used in fish farming, and this guide is aimed at people working in this field of aquaculture.

The Kodiak Jig Initiative: Ensuring viability of the small-boat jig fleet through market and policy solutions

Sat, 22 May 2021 00:00:00 +0000

Theresa Peterson Fisheries Policy Director, Alaska Marine Conservation Council Rachel Donkersloot Coastal Cultures Research

The social, cultural and economic sustainability of fishing towns and villages in Alaska are dependent on the success of their fisheries. This case study presents the Kodiak Jig Initiative as an example of a highly collaborative fishermen-led effort to create and maintain small-scale fishing opportunities in the Gulf of Alaska. It discusses specific policy and market-based challenges and solutions to ensuring the viability of the small-boat Kodiak jig fleet. The case study describes marketing initiatives, mechanisms and partnerships resulting in the establishment of niche markets and the Kodiak Jig Seafoods brand. These efforts have resulted in significant increases in the dockside value of Pacific cod and rockfish for the small-boat fleet. Also discussed are important policy provisions advanced by jig fishermen and partners to successfully secure quota set-asides that have served as an important foundation for the marketing initiatives presented herein. These set-asides provide affordable entry-level opportunities for new and young fishermen as well as those seeking more diversified access. Combined, these policy- and market-based efforts have helped to ensure viable access and livelihood opportunities for Kodiak’s small-boat jig fleet. The successes and challenges of the Kodiak Jig Initiative serve as examples that can assist other fishing communities and fleets in developing approaches that fit their specific needs.

The recirculation system, step by step

Wed, 15 Jul 2020 00:00:00 +0000

In a recirculation system it is necessary to treat the water continuously to remove the waste products excreted by the fish, and to add oxygen to keep the fish alive and well. A recirculation system is in fact quite simple. From the outlet of the fish tanks the water flows to a mechanical filter and further on to a biological filter before it is aerated and stripped of carbon dioxide and returned to the fish tanks. This is the basic principle of recirculation.

The FAO-Thiaroye processing technique: Facilitating social organization, empowering women, and creating market access opportunities in West Africa

Sat, 22 May 2021 00:00:00 +0000

Alexander Ford Policy, Economics and Institutions Branch FAO Fisheries and Aquaculture Department Rome, Italy

Aina Randrianantoandro Omar Riego Peñarubia Product, Trade and Marketing FAO Fisheries and Aquaculture Department Rome, Italy

Over the past decade the FAO-Thiaroye processing technique (FTT), a healthier, more economic and environmentally sustainable method of fish smoking, has been introduced in fishing communities throughout Africa, Asia and the Pacific. This case study examines the role of the FTT in West Africa, focusing on its function as a technology that reduces human health impacts and fish losses, improves fuel efficiency, increases product quality and facilitates access to international markets. The study also examines the role the FTT has played in enabling the social organization of the processors who use it and in advancing gender equality and women’s empowerment in West Africa. Further, it highlights elements of the FTT that support the value chains of small-scale fisheries reliant on the smoked fish trade, and also their limitations and areas where further study is needed to understand the impact on the value chain and those involved. Finally, the case study presents recommendations to ensure management of the FTT is effective.

Fish species in recirculation

Wed, 15 Jul 2020 00:00:00 +0000

A recirculation system is a costly affair to build and to operate. There is competition on markets for fish and production must be efficient in order to make a profit. Selecting the right species to produce and constructing a well functioning system are therefore of high importance. Essentially, the aim is to sell the fish at a high price and at the same time keep the production cost at the lowest possible level.

Fish traders and processors network: Enhancing trade and market access for small-scale fisheries in the West Central Gulf of Guinea

Sat, 22 May 2021 00:00:00 +0000

Raymond Kwojori Ayilu Faculty of Arts and Social Sciences, University of Technology, Sydney, Australia Sarah Appiah Department of Economics, University of Ghana, Accra

From 2014 to 2018, the Fish Trade Project (a joint project of the WorldFish Center, the African Union Interafrican Bureau for Animal Resources, and the New Partnership for Africa’s Development) implemented trade and market-driven initiatives to support small-scale fisheries in the subregion of the Fishery Committee for the West Central Gulf of Guinea (FCWC). One initiative was the establishment of the FCWC Fish Traders and Processors Network (FCWC FishNET), a platform composed of small-scale traders and processors, with the objective of informing policy gaps and designing market-driven incentives to leverage the collective power of its members to facilitate regional trade. This case study reviews FCWC FishNET activities to reflect on the role of socio- economic trade networks in small-scale fisheries, in line with specific recommendations of Chapter 7 of the Voluntary Guidelines for Securing Sustainable Small-Scale Fisheries in the Context of Food Security and Poverty Eradication. Secondary data supplemented by primary survey were used. The study emphasizes FCWC FishNET’s activities in promoting quality smoked fish products, reducing post-harvest losses, and popularizing the FAO-Thiaroye processing technique to eliminate the health threats posed by the Chorkor kiln. Also discussed is the use of Fisheries Learning Exchanges to promote better fish handling, processing and packaging techniques as a means of adding value and diversifying trading channels for fish products. The study finds that FCWC FishNET has engendered greater trust among network members, allowing traders to conduct business with each other on a credit basis and improving the overall communication and business experience. Similarly, it has facilitated initiatives to reduce post-harvest losses by improving processing and trading facilities. Finally, the case study emphasizes the compelling role of trade networking in small-scale fisheries discourse while providing lessons to practitioners and policymakers in fisheries.

Project planning and implementation

Wed, 15 Jul 2020 00:00:00 +0000

The idea of building a recirculation fish farm is often based on very different views on what is important and what is interesting. People tend to focus on things they already know or things they find most exciting, and in the process forget about other aspects of the project.

Five major issues should be addressed before launching a project:

Sales prices and market for the fish in question
Site selection including licences from authorities

Seafood direct marketing: Supporting critical decision-making in Alaska and California

Sat, 22 May 2021 00:00:00 +0000

Caroline Pomeroy California Sea Grant, Scripps Institution of Oceanography, University of California, San Diego Institute of Marine Sciences, University of California, Santa Cruz

Sunny Rice Alaska Sea Grant Marine Advisory Program College of Fisheries and Ocean Sciences, University of Alaska Fairbanks

Carolynn Culver California Sea Grant, Scripps Institution of Oceanography, University of California, San Diego Marine Science Institute, University of California, Santa Barbara

Victoria Baker Alaska Sea Grant Marine Advisory Program College of Fisheries and Ocean Sciences, University of Alaska Fairbanks

Running a recirculation system

Wed, 15 Jul 2020 00:00:00 +0000

Figure 5.1 Water quality and flow in filters and fish tanks should be examined visually and frequently. Water is distributed over the top plate of a traditional trickling filter (degasser) and distributed evenly through the plate holes down through the filter media.

Moving from traditional fish farming to recirculation significantly changes the daily routines and skills necessary for managing the farm. The fish farmer has now become a manager of both fish and water. The task of managing the water and maintaining its quality has become just as important, if not more so, than the job of looking after the fish. The traditional pattern of doing the daily job on a traditional flow-through farm has changed into fine tuning a machine that runs constantly 24 hours a day. Automatic surveillance of the whole system ensures that the farmer has access to information on the farm at all times, and an alarm system will call if there is an emergency.

Fair Trade: Certification of a yellowfin tuna handline fishery in Indonesia

Sat, 22 May 2021 00:00:00 +0000

Rui Bing Zheng Ashley Apel Sven Blankenhorn Fair Trade USA

Deirdre Elizabeth Duggan Jaz Simbolon Yayasan Masyarakat dan Perikanan Indonesia (MDPI)

Helen Packer Anova Food

Fair Trade enables greater equity in value chains and ensures the benefits of trade and export are spread among producers. For a fishery to receive Fair Trade Certification, it must first comply with the Capture Fisheries Standard and its core objectives of fisher and worker empowerment, economic development of communities, social responsibility, and environmental stewardship. This case study outlines the ways in which the Fair Trade model aligns with several provisions laid out in the Voluntary Guidelines for Securing Sustainable Small-Scale Fisheries in the context of Food Security and Poverty Eradication. The recommendations pertain particularly to Chapter 7 of the SSF Guidelines on value chains, post-harvest, and trade, through the case of the certified Indonesia Western and Central Pacific Ocean yellowfin tuna handline fishery.

Waste water treatment

Wed, 15 Jul 2020 00:00:00 +0000

Farming fish in a recirculation system where the water is constantly reused does not make the waste from the fish production disappear. Dirt or excretions from the fish still have to end somewhere.

Figure 6.1 Excretion of nitrogen (N) and phosphorus (P) from farmed fish. Note the amount of N excreted as dissolved matter. Source: Biomar and the Environmental Protection Agency, Denmark.

The biological processes within the RAS will in a smaller scale reduce the amount of organic compounds, because of simple biological degradation or mineralisation within the system. However, a significant load of organic sludge from the RAS will still have to be dealt with.

Madagascar's mud crab fishery: How fishers can earn more while catching less

Sat, 22 May 2021 00:00:00 +0000

Zbigniew Kasprzyk Independent fisheries consultant Antananarivo, Madagascar

Adrian Levrel Blue Ventures London, UK

Madagascar, one of the poorest countries in the world, has large coastal communities who rely heavily on various small-scale fisheries, such as mangrove mud crab (Scylla serrata), for income. There has been a marked increase in mangrove mud crab fishing due to high international demand, and it is now the country’s third most valuable seafood export. This has led to overfishing, with documented decreases in quantity and average size of catches. Additionally, post-harvest losses along the value chain lead to lost value, due to poor handling, transport and storage. This lost value further reduces the earnings and food security of the coastal communities who depend on this fishery. The Smartfish Programme, jointly implemented by the Indian Ocean Commission and the Food and Agriculture Organization of the United Nations and funded by the European Union, worked with the Government of Madagascar’s ministry responsible for fisheries resources and locally-based NGOs including Blue Ventures and WWF, to assess methods of reducing exploitation of the fishery and increasing benefits to fishers and the wider supply chain. This case study reviews practical approaches to recover lost value in the mangrove mud crab fishery, highlighting low cost interventions that can increase yields even in the face of falling catches. The value of catches were augmented by obtaining higher prices for export crabs (around half of the annual harvest) and reducing post-harvest losses, providing a practical example of how low-cost changes in behaviour, logistics and technique can reduce post-harvest losses, helping fishers to earn more while catching less.

Disease

Wed, 15 Jul 2020 00:00:00 +0000

For the innovative entrepreneur there are several opportunities in this kind of recycled aquaculture. The example of combining different farming systems can be developed further into recreational businesses, where sport fishing for carp or put & take fishing for trout can be part of a larger tourist attraction including hotels, fish restaurants and other facilities.

There are many examples of recirculation systems operating without any disease problems at all. In fact, it is possible to isolate a recirculation fish farm completely from unwanted fish pathogens. Most important is to make sure that eggs or fish stocked in the facility are absolutely disease free and preferably from a certified disease free strain. Make sure that the water used is disease free or sterilised before going into the system; it is far better to use water from a borehole, a well, or a similar source than to use water coming directly from the sea, river or lake. Also, make sure that no one entering the farm is bringing in any diseases, whether they are visitors or staff.

State-led fisheries development: Enabling access to resources and markets in the Maldives pole-and- line skipjack tuna fishery

Sat, 22 May 2021 00:00:00 +0000

Zacari Edwards International Pole and Line Foundation London, United Kingdom

Hussain Sinan Marine Affairs Program Dalhousie University Halifax, Nova Scotia B3H 4R2, Canada

M. Shiham Adam International Pole and Line Foundation Malé, the Republic of the Maldives

Alice Miller International Pole and Line Foundation London, United Kingdom

The Maldives is a nation heavily reliant on its marine resources, none more so than the skipjack tuna caught in its pole-and-line fishery. Maldivian citizens derive huge benefits from the fishery as a result of effective State stewardship of the resource. This paper presents key actions along the value chain of the Pole-and-Line Skipjack Tuna Fishery Maldivian Government has taken to support and facilitate improvements along the value chain of the Pole-and-Line Skipjack Tuna Fishery and by extension demonstrates how these many government actions have resulted in an alignment with the recommendations set out in Chapter 7 of the Voluntary Guidelines for Securing Sustainable Small-Scale Fisheries in the Context of Food Security and Poverty Eradication, particularly paragraphs 7.6-7.9. By highlighting the good practices of the Maldivian Government, this paper pinpoints the key lessons that can be learned from the case of the Maldives as well as the actions that can be replicated by other governments from countries highly dependent on fisheries affected by globalized market demands.

Case story examples

Wed, 15 Jul 2020 00:00:00 +0000

Salmon smolt production in Chile

Growth in the Chilean salmon production during the 90s required an increasing supply of smolts from freshwater to be stocked in cages for grow-out at sea. Smolts were produced in river water or in lakes, where the water was too cold and the environment was suffering. Introducing recirculation helped smolt farmers to produce vast amounts at a significantly lower cost in an environmentally friendly manner. Also, the optimal rearing conditions resulted in faster growth, which made it possible to produce four smolt batches per year instead the previous one batch a year technology. This shift made the whole chain of production much smoother with a constant flow of smolt being stocked into the cages from where large salmon would be harvested at a constant rate at the right size ready for the market.

Fishery Improvement Projects: In the context of small-scale fisheries value chains, post-harvest operations and trade

Sat, 22 May 2021 00:00:00 +0000

Alexander Ford Joseph Zelasney Policy, Economics and Institutions Branch FAO Fisheries and Aquaculture Department Rome, Italy

Fishery Improvement Projects (FIPs) are multistakeholder partnerships designed to encourage value chain actors to improve fisheries sustainabiliy using market incentives. Initially applied to large-scale fisheries, for the past ten years the FIP model has also been applied in other contexts, including small-scale fisheries. FIPs facilitate coordination between relevant value chain actors and promote multistakeholder dialogue. However, FIPs have been criticized for not engaging governments and small- scale fishery actors or ensuring the fair distribution of benefits for fishing communities. This case study provides a historical overview of FIPs and considers their strenghts and weaknesses as a mechanism to operationalize the recommendations laid out in Chapter 7 of the Voluntary Guidelines for Securing Sustainable Small-Scale Fisheries in the Context of Food Security and Poverty Eradication, particularly paragraphs 7.1 and 7.8, which aim to ensure that post-harvest actors are included in decision-making processes and to ensure that effective fisheries management systems are implemented to prevent market-driven overexploitation of the natural resource and those dependent on it, respectively. FIPs have the potential to drive collaborative management in small- scale fisheries, but to do so effectively greater inclusion of fishing communities and government authorities is needed.

Your Ammonia Test Is Lying to You. Here Is What Actually Kills Fish.

Sun, 01 Mar 2026 00:00:00 +0000

Levi and Jeff Lee run a catfish farm in Macon, Mississippi. For years, their summer nights looked the same: wake up at 2 AM, walk the pond banks with a flashlight, listen for the sound of fish gasping at the surface. If they heard it, they fired up the paddlewheel aerators. If they slept through it, they woke up to dead fish.

That is not a monitoring system. That is a grower betting their livelihood on whether they hear splashing in the dark.

Your Soil Test Results Are Already Stale. Here Is What to Do About It.

Sun, 01 Mar 2026 00:00:00 +0000

You pull soil samples in February. You ship them to the lab. Results come back in March – two to four weeks later, depending on the lab and the season. By the time you read the report, your planting window is open. Maybe closed.

That report tells you what your soil looked like on the day you sampled it. It says nothing about what happened since. Not the heavy rain that leached nitrogen. Not the compaction from equipment traffic. Not the moisture gradient across the east end of the field that your sampling grid missed entirely.

Why Aquaponics Is Poised to Transform Small-Scale Farming by 2035

Sun, 13 Jul 2025 00:00:00 +0000

The farming landscape is shifting beneath our feet, and small commercial farmers who recognize the signs early stand to benefit most. While traditional agriculture grapples with rising input costs, water scarcity, and consumer demands for cleaner food, a different approach is quietly gaining momentum. The aquaponics market is projected to more than double from USD 1.8 billion in 2025 to USD 3.9 billion by 2035, representing an 8.1% annual growth rate that few agricultural sectors can match.

Smart Technology Revolution in Aquaponics: How CEA and IoT Are Transforming Small Commercial Farming Operations

Mon, 23 Jun 2025 00:00:00 +0000

Smart Technology Revolution in Aquaponics: How CEA and IoT Are Transforming Small Commercial Farming Operations

When Tom Richardson first walked through Blue Ridge Aquaculture’s facility in rural Virginia, he couldn’t believe what he was seeing. Fish swimming in precisely controlled tanks while lettuce, herbs, and microgreens thrived in vertical growing towers—all managed by computers that monitored every pH fluctuation, temperature change, and nutrient level in real-time. As a small commercial farmer struggling with unpredictable weather and rising costs, Tom realized he was witnessing the future of agriculture: a technology-driven approach that could eliminate many of the challenges that kept him awake at night.

Solar-Powered Vertical Farms and Educational Initiatives: How Dutch Innovation and Caribbean Education Are Reshaping Small-Scale Agriculture

Sun, 22 Jun 2025 00:00:00 +0000

When Maria Santos first heard about vertical farms powered entirely by solar energy, she thought it sounded like science fiction. As a small commercial grower in California struggling with rising electricity costs and water restrictions, the idea of growing crops in stacked systems using free solar power seemed too advanced for operations like hers. Two years later, after visiting the Netherlands and observing similar innovations being adapted by farmers with budgets similar to her own, Maria realized that what seemed impossible was actually the future of sustainable farming—and it was arriving faster than she’d imagined.

Mastering Hydroponic Nutrient Solutions: The Complete Guide to Formulation, Balance, and Optimization for Commercial Growers

Fri, 20 Jun 2025 00:00:00 +0000

The difference between a thriving hydroponic operation and one that struggles often comes down to a few milliliters of solution and a tenth of a pH point. When Marcus Chen started his commercial lettuce operation three years ago, he thought nutrient management would be straightforward—just follow the manufacturer’s recommendations and watch the plants grow. Six months and several crop failures later, he learned that successful hydroponic nutrition requires understanding not just what nutrients plants need, but how they interact with water chemistry, environmental conditions, and each other in ways that can make or break a harvest.

Understanding Nutrient Profiles: How to Optimize Your Aquaponics System for Maximum Crop Yield

Fri, 20 Jun 2025 00:00:00 +0000

When David Martinez first started his aquaponics operation, he thought the hardest part would be keeping the fish alive. Three months later, with healthy tilapia swimming in crystal-clear water but stunted, yellowing plants struggling in his grow beds, he learned a crucial lesson: successful aquaponics isn’t just about fish and plants coexisting—it’s about creating the precise nutrient environment where both can thrive.

The challenge in aquaponics lies in managing a complex biological system where fish waste must provide complete nutrition for plants while maintaining water quality that keeps fish healthy. Unlike hydroponics, where growers can precisely control every nutrient input, aquaponics requires understanding how fish species, feeding schedules, and system design interact to create—or limit—the nutrients available for plant growth.

The Invisible Killer: How Poor Oxygen Management Destroys Aquaponics Systems (And the Simple Solutions That Save Them)

Sun, 15 Jun 2025 00:00:00 +0000

Your fish are gasping at the surface. Your plants are wilting despite adequate water. Your once-thriving aquaponics system is collapsing, and you can’t figure out why. The culprit might be invisible to the naked eye, but its effects are devastating: inadequate dissolved oxygen levels that are slowly suffocating your entire system.

Oxygen management in aquaponics isn’t just about keeping fish alive—it’s about maintaining the complex biological processes that make the entire system function. Fish, plants, and beneficial bacteria all compete for the same dissolved oxygen, and when supply can’t meet demand, the results are swift and catastrophic. What makes this particularly insidious is that oxygen problems often develop gradually, with subtle warning signs that many growers miss until it’s too late.

The Reality of Aquaponics and Vertical Farming for Small Commercial Growers: Navigating Innovation, Economics, and Operational Success

Sun, 15 Jun 2025 00:00:00 +0000

The phone call came at 3 AM. Sarah’s aquaponics system had crashed overnight—fish gasping at the surface, plants wilting, and thousands of dollars of investment hanging in the balance. Six months later, her farm is thriving, but the journey taught her what no sales brochure mentioned: success in controlled environment agriculture isn’t just about the technology you buy, it’s about understanding the intricate dance between biology, economics, and operational discipline.

How EU Training Programs and Smart Agro-Hubs Are Revolutionizing Small-Scale Farming Through Aquaponics and Hydroponics

Wed, 11 Jun 2025 00:00:00 +0000

When Kwame Asante received word that he’d been selected for agricultural training through a European Union-funded program, he had no idea he was about to learn farming methods that would triple his income within two years. Like thousands of other smallholder farmers across developing regions, Asante discovered that aquaponics and hydroponics weren’t just high-tech farming buzzwords—they were practical solutions that could transform his small plot into a productive, year-round operation.

Navigating the Hydroponic Maze: How Smart Technology Transforms Complex Farm Management Challenges

Tue, 10 Jun 2025 00:00:00 +0000

Hydroponic farming represents one of agriculture’s most promising frontiers, offering unprecedented control over growing conditions and the potential for dramatically increased yields in minimal space. Yet beneath the gleaming greenhouse surfaces and precisely controlled environments lies a complex web of management challenges that can overwhelm even experienced farmers. For small commercial growers, these challenges aren’t just technical hurdles—they’re potential business killers that can transform promising ventures into costly failures.

Every hydroponic system operates on a knife’s edge of precision. A single pump failure can destroy an entire crop within hours. A pH imbalance can stunt plant growth for weeks. An undetected pest outbreak can spread through an entire facility faster than traditional soil-based infestations. The very factors that make hydroponics so productive—closed-loop systems, concentrated nutrients, controlled environments—also create vulnerabilities that demand constant vigilance and rapid response.

Community Innovation Meets Commercial Reality: How Aquaponics Programs Are Bridging the Gap Between Education and Profitable Farming

Sun, 08 Jun 2025 00:00:00 +0000

The aquaponics industry sits at a fascinating crossroads where cutting-edge agricultural technology meets age-old challenges of profitability and sustainability. While the promise of integrated fish and plant production continues to attract innovators and entrepreneurs, the reality of building viable businesses around these systems remains complex. Recent developments across commercial startups, community initiatives, and educational programs reveal both the potential and the persistent obstacles that define this evolving sector.

At the commercial forefront, Greenscale is establishing an indoor combined aquaculture and hydroponic facility in Boise, focusing on producing pesticide-free food with minimal water usage, using controlled environment agriculture methods. This ambitious project represents the kind of scaling effort that has long been considered necessary for aquaponics to move from niche hobby to mainstream agriculture. Yet the company’s experience also illuminates the fundamental challenges that continue to plague the industry.

The Silent Profit Killers: How Poor Nutrient Monitoring Is Costing Hydroponic Growers Thousands

Sun, 08 Jun 2025 00:00:00 +0000

Your lettuce crop looked perfect yesterday. Today, half the leaves are yellowing and growth has stalled. Your tomatoes were thriving last week, but now they’re showing classic signs of nutrient burn. Sound familiar? These scenarios play out in hydroponic operations worldwide, and in most cases, they’re completely preventable through proper nutrient solution monitoring.

For commercial hydroponic growers, nutrient solution management represents the difference between profitable harvests and costly failures. Unlike soil-based agriculture where nutrient imbalances develop slowly, hydroponic systems can shift from optimal to catastrophic within days—or even hours. The concentrated nature of hydroponic solutions means small changes in concentration or pH can have dramatic effects on plant health, growth rates, and ultimately, your bottom line.

The Aquaponics Paradox: Why the World's Most Water-Efficient Food System Still Can't Scale

Sat, 07 Jun 2025 00:00:00 +0000

In a world where 2 billion people lack access to safe drinking water and 828 million face hunger, aquaponics should be revolutionizing global food production. This innovative system uses 90% less water than traditional agriculture, produces both fish and vegetables simultaneously, and can operate in areas where soil farming is impossible. Yet despite decades of research and hundreds of millions in development funding, aquaponics remains largely confined to demonstration projects and niche applications.

The Secret Army That Can Cut Your Pest Control Costs by 80%: How Beneficial Bugs Are Revolutionizing Farm Profitability

Sat, 07 Jun 2025 00:00:00 +0000

Every morning, while you’re checking water levels or adjusting nutrient solutions, millions of tiny workers are already on the job in your fields and greenhouses. They’re hunting down aphids, pollinating your crops, and breaking down organic matter—all without asking for wages, benefits, or even a lunch break. These are your beneficial insects, and they represent one of the most underutilized profit centers in modern agriculture.

For small commercial farmers operating on razor-thin margins, the economics are compelling. A single ladybug can consume up to 50 aphids per day. A small population of parasitic wasps can eliminate entire pest colonies before you even notice they exist. Native bees can increase fruit yields by 30% or more through improved pollination. Yet most farmers are inadvertently driving these valuable allies away through practices that prioritize short-term pest control over long-term economic sustainability.

Aquaponics vs Hydroponics: A Smart, Sustainable Path to Modern Farming

Fri, 06 Jun 2025 00:00:00 +0000

Imagine stepping into a future where fresh produce and healthy fish share a symbiotic home—a world where gardening evolves from a simple hobby to a sustainable lifestyle. For many modern growers, the decision between aquaponics and hydroponics isn’t just about technique—it’s about embracing a method that aligns with both environmental stewardship and practical efficiency. Whether you’re eyeing a backyard project or contemplating a larger-scale endeavor, these two cutting-edge systems offer distinct advantages and challenges.

Sump Tanks Decoded: The Game-Changing Component Your Small Aquaponics System Needs (And When You Can Skip It)

Fri, 06 Jun 2025 00:00:00 +0000

You’re standing in your basement, garage, or spare room, looking at your newly assembled aquaponics system. The fish tank is ready, the grow bed is positioned, and the water pump is humming. But something feels off. The water level fluctuates wildly when the pump cycles. You’re constantly adding water to replace what evaporates. And that nagging worry persists: what happens if the pump fails while you’re away for the weekend?

10 Essential Farm Courses Every Agricultural Professional Should Consider: Your Complete Guide to Growing Success

Wed, 04 Jun 2025 00:00:00 +0000

The agricultural industry is experiencing unprecedented transformation, driven by technological advances, environmental concerns, and evolving consumer demands. For small commercial farmers and agricultural professionals, staying competitive requires continuous learning and skill development. Today’s farmers must be part agriculturist, part technologist, part business person, and part environmental steward.

Whether you’re a seasoned farmer looking to modernize your operation, a recent graduate seeking specialized skills, or someone considering a career change into agriculture, the right educational foundation can make the difference between struggling to keep up and thriving in this dynamic industry. Farm courses offer structured pathways to acquire essential knowledge, hands-on experience, and industry-recognized credentials that employers and customers value.

Dissolved Oxygen in Hydroponics vs. Aquaponics: The Lifeblood of Your Growing System

Wed, 04 Jun 2025 00:00:00 +0000

Growing food in controlled environments comes with complex biological and chemical considerations. Among these, dissolved oxygen (DO) ranks as one of the most critical factors affecting your system’s health and productivity—yet it often receives less attention than pH, nutrients, or temperature management.

Whether you’re running a hydroponic or aquaponic system, understanding how oxygen behaves in your water can mean the difference between thriving crops and systemic failure. Let’s examine the distinct oxygen requirements of each system and practical approaches to maintaining optimal levels.

The Fish That Will Make or Break Your First Aquaponics System: A Beginner's Guide to Choosing the Right Species

Tue, 03 Jun 2025 00:00:00 +0000

Standing in front of your newly assembled 50-gallon aquaponics system, you’re faced with one of the most crucial decisions of your aquaponics journey: which fish to stock. This single choice will determine whether your system thrives or struggles, whether your plants flourish or fail, and whether you’ll be celebrating your first harvest or troubleshooting water quality disasters six months from now.

For beginners venturing into aquaponics, fish selection isn’t just about personal preference or what looks appealing at the pet store. Your fish serve as the living engines of your system, converting feed into the nutrients that fuel plant growth. They’re also the most vulnerable component—sensitive to water quality fluctuations, temperature changes, and feeding mistakes that can wipe out your entire fish population in a matter of days.

The Indoor Farmer's Light Bible: How to Choose Grow Lights That Double Your Hydroponic Yields

Tue, 03 Jun 2025 00:00:00 +0000

Your hydroponic vegetables are struggling despite perfect nutrients and water management. Your lettuce is spindly, your tomatoes won’t flower, and your spinach bolts prematurely. The culprit isn’t your nutrient solution or pH levels—it’s likely your lighting setup. In indoor hydroponic farming, light isn’t just important; it’s the single factor that can make or break your entire operation.

For commercial hydroponic growers, lighting represents both the greatest opportunity and the biggest challenge. Get it right, and you can achieve yields that exceed field-grown crops by 300-400%. Get it wrong, and you’ll watch your investment literally wither under inadequate illumination.

How Smart Agriculture Hubs and Advanced Vertical Systems Are Transforming Small-Scale Farming

Mon, 02 Jun 2025 00:00:00 +0000

The agricultural landscape is shifting beneath our feet, and small commercial farmers who recognize this early stand to benefit most. While traditional farming grapples with shrinking arable land, water scarcity, and climate unpredictability, a new wave of vertical farming technologies and smart agriculture infrastructure is creating opportunities that seemed impossible just a few years ago.

Consider this: aeroponic precision farming systems spray nutrient-loaded solutions intermittently on roots suspended in air, enhancing plant growth efficiently in limited spaces. What makes this remarkable isn’t just the technology itself, but how it’s becoming accessible to operations that don’t require massive capital investment or industrial-scale facilities.

Aquaculture 2025: Riding the Wave of Technological Innovation and Sustainable Transformation

Sun, 01 Jun 2025 00:00:00 +0000

Aquaculture stands at the threshold of a revolutionary transformation in 2025, driven by an unprecedented convergence of technological innovation, environmental awareness, and changing consumer preferences. For an industry that produces more than half of the world’s seafood, these changes represent more than incremental improvements—they signal a fundamental reimagining of how we raise aquatic protein and the role it plays in global food security.

The aquaculture landscape of 2025 reflects years of adaptation to mounting pressures: climate change impacts that threaten traditional production systems, consumer demands for sustainability and transparency, and technological capabilities that enable precision farming at scales previously unimaginable. Small commercial farmers who understand these trends and position themselves accordingly will find unprecedented opportunities to compete with larger operations while contributing to sustainable food systems.

The Hidden Food Safety Risks in Your Aquaponics System - And How to Eliminate Them

Sun, 01 Jun 2025 00:00:00 +0000

Your customers trust that the lettuce, tomatoes, and herbs coming from your aquaponics operation are not only fresh and flavorful, but safe to eat. Yet beneath the surface of every aquaponics system lies a complex biological process that, if not properly managed, can transform your profitable operation into a food safety nightmare that destroys your reputation and threatens your livelihood.

Food safety in aquaponics isn’t just about following basic hygiene practices—though those matter. It’s about understanding and managing a living ecosystem where fish waste becomes plant nutrition through microbial processes that can either create the cleanest growing environment possible or harbor dangerous pathogens that contaminate your entire harvest.

Desert Innovation: How Hydroponics and Aquaponics Are Revolutionizing Middle Eastern Agriculture

Sat, 31 May 2025 00:00:00 +0000

Across the vast expanses of the Middle East, where ancient trade routes once connected civilizations and agricultural innovations first transformed human society, a new agricultural revolution is taking shape. In a region where water is more precious than oil and arable land remains scarce, farmers and agricultural entrepreneurs are turning to technologies that seemed like science fiction just decades ago. Hydroponics and aquaponics are emerging as game-changing solutions that promise not only to feed growing populations but to do so while using a fraction of the water required by traditional farming methods.

Growing the Future: How Universities Are Transforming Agriculture Education Through Smart Aquaponics and Hydroponics

Sat, 31 May 2025 00:00:00 +0000

Across university campuses nationwide, a quiet revolution is taking root in agricultural education. Behind greenhouse walls and in research laboratories, students are learning to grow food using systems that consume 90% less water than traditional farming, produce crops year-round regardless of climate, and integrate fish, plants, and beneficial bacteria into self-sustaining ecosystems that could reshape how we think about food production.

These aren’t just academic exercises—they’re hands-on laboratories where the next generation of agricultural professionals is learning to combine centuries-old growing principles with cutting-edge technology. Universities are discovering that aquaponics and hydroponics programs offer something traditional agricultural education often lacks: immediate, measurable results that students can optimize through data collection, system monitoring, and technological innovation.

Navigating Innovation and Sustainability: What New Aquaponics and Aquaculture Trends Mean for Small-Scale Farmers

Sat, 31 May 2025 00:00:00 +0000

The controlled environment agriculture landscape is experiencing a period of intense innovation and equally intense scrutiny. For small commercial farmers watching from the sidelines, recent developments paint a complex picture of opportunity shadowed by persistent challenges that demand careful consideration before making significant investments.

Take the case of Greenscale’s new aquaponics facility in Boise, Idaho. Construction began in spring 2025, combining aquaculture and hydroponics for efficient food production, but the project faces high upfront and operational costs, a common challenge for CEA. As one project manager aptly described it, “The project fit the ‘big, messy’ criteria,” reflecting the ambitious nature of new aquaponics initiatives.

The Five Fish Diseases That Can Destroy Your Aquaculture Operation - And How to Stop Them

Tue, 27 May 2025 00:00:00 +0000

When you wake up to find your fish floating belly-up or covered in mysterious white spots, every minute counts. For small commercial farmers running aquaculture operations, a disease outbreak isn’t just a setback—it’s a potential business killer that can wipe out months of investment in a matter of days.

The harsh reality is that fish diseases don’t announce themselves with advance warning. They strike fast, spread faster, and can devastate an entire system before you’ve even identified the problem. But here’s what separates successful aquaculture operations from those that fail: understanding the enemy before it arrives at your door.

Aquaponics: The Sustainable Farming Revolution for Small Commercial Growers

Mon, 26 May 2025 00:00:00 +0000

For small commercial farmers facing rising input costs, water scarcity, and market competition, finding efficient and sustainable production methods is no longer optional—it’s essential. Aquaponics offers a compelling solution by creating a symbiotic relationship between fish and plants that addresses many of these challenges head-on.

What Is Aquaponics?

Aquaponics combines aquaculture (fish farming) and hydroponics (soilless plant cultivation) into a single integrated system. In this closed-loop ecosystem, fish waste provides essential nutrients for plants, while the plants naturally filter the water, which is then recycled back to the fish tanks. This mutually beneficial arrangement mimics natural ecosystems while maximizing production efficiency.

The $50 Billion Promise: Why Aquaponics Hasn't Conquered the World Yet (And Where It Will Win First)

Sun, 25 May 2025 00:00:00 +0000

Aquaponics represents one of the most promising agricultural innovations of the 21st century. It uses 90% less water than traditional farming, produces both fish and vegetables, and can grow food in places where soil-based agriculture is impossible. With global food insecurity affecting over 800 million people and climate change making traditional farming increasingly difficult, aquaponics should be revolutionizing agriculture worldwide.

Yet despite decades of research, millions in development funding, and countless pilot projects, aquaponics remains a niche practice adopted by relatively few commercial operations. While the technology works brilliantly in controlled environments and demonstration projects, it has failed to achieve the widespread adoption that many experts predicted would happen by now.

The Hidden Threat to Your Aquaponics Profits: How Nutrient Deficiencies Are Sabotaging Your Harvest

Thu, 22 May 2025 00:00:00 +0000

Your lettuce leaves are turning yellow again. The tomatoes that should be thriving are stunted and pale. Your fish seem healthy enough, but somehow the plants just aren’t performing like they should. If this sounds familiar, you’re facing one of aquaponics’ most insidious challenges: nutrient deficiencies that silently erode your profits one harvest at a time.

Unlike soil-based farming where you can simply add fertilizer, aquaponics operates as a delicate biological balance where every component affects every other component. When that balance tips, the symptoms might appear in your plants, but the root cause often lies in the complex interplay between fish waste, bacterial conversion, water chemistry, and plant uptake.

Aquaponics 2025: The Revolutionary Year That Will Transform Sustainable Agriculture

Mon, 19 May 2025 00:00:00 +0000

As we stand at the threshold of 2025, the aquaponics industry is experiencing a convergence of technological innovation, environmental urgency, and market demand that promises to fundamentally reshape how we approach sustainable food production. For small commercial farmers and agricultural entrepreneurs, this year represents not just another step in agricultural evolution, but a potential turning point that could democratize access to profitable, environmentally responsible farming methods.

The confluence of factors driving aquaponics forward in 2025 reflects broader shifts in global agriculture: urbanization pressures that demand local food production, climate change impacts that require water-efficient farming methods, and consumer preferences that increasingly favor sustainably produced food. Unlike previous years where aquaponics remained largely experimental or niche, 2025 marks the transition toward mainstream adoption driven by proven economic viability and technological maturity.

Building Your Hydroponic Dream Team: A Complete Guide to Essential Farm Positions and Career Opportunities

Mon, 19 May 2025 00:00:00 +0000

The hydroponic industry is experiencing unprecedented growth as consumers increasingly demand fresh, locally-grown produce year-round, and farmers seek efficient, sustainable growing methods that maximize yields while minimizing resource use. This expansion has created a diverse ecosystem of career opportunities that didn’t exist a generation ago, from highly technical roles requiring advanced scientific knowledge to hands-on positions perfect for those who prefer working directly with plants and equipment.

For small commercial farmers and agricultural entrepreneurs, understanding these various roles is crucial for building effective teams and scaling operations successfully. Unlike traditional farming, which often relies on generalized agricultural knowledge, hydroponic operations require specialized skills that combine plant science, engineering, technology, and business acumen. Each position contributes unique value to the operation, and the synergy between these roles often determines whether a hydroponic farm thrives or merely survives.

Thriving in Extremes: How to Build Bulletproof Aquaponics Systems for Alaska's Winters and New Mexico's Scorching Summers

Mon, 19 May 2025 00:00:00 +0000

Your thermometer reads -40°F outside, but inside your insulated aquaponics greenhouse, lettuce is growing and trout are thriving. Or perhaps you’re watching the desert sun bake the landscape at 115°F while your shaded tilapia tanks maintain perfect growing conditions. This isn’t fantasy—it’s the reality for aquaponics farmers who’ve mastered the art of environmental control in some of the planet’s most challenging climates.

Most aquaponics guides assume you’re operating in moderate, stable conditions. But what if you’re farming in Alaska’s bone-chilling winters, New Mexico’s scorching deserts, or any of the countless places where extreme weather makes conventional agriculture nearly impossible? The truth is, these challenging environments can actually provide advantages for aquaponics systems—if you understand how to harness and control them.

The Power of Water: Understanding Small-Scale Aquaponics and Hydroponics

Sun, 18 May 2025 00:00:00 +0000

Small-scale aquaponic and hydroponic systems are revolutionizing how commercial farmers approach food production—especially those with space limitations or environmental challenges. These soil-less growing methods offer compelling advantages in resource efficiency and yield potential that traditional soil-based agriculture simply can’t match.

At their core, both methods represent a fundamental shift in how we think about plant cultivation. Rather than relying on soil as the medium for nutrient delivery, these systems create carefully controlled environments where plants receive precisely what they need, when they need it.

The Invisible Foundation: How Beneficial Microorganisms Drive Nutrient Cycling in Aquaponics Systems

Sat, 17 May 2025 00:00:00 +0000

In the bustling ecosystem of an aquaponics system, fish swim through clear water while plants stretch toward the light, their roots bathed in nutrient-rich solution. To most observers, this appears to be a simple arrangement—fish provide waste, plants absorb nutrients, water circulates endlessly. But this surface-level understanding misses the most crucial players in the entire operation: billions of microscopic organisms working tirelessly to transform waste into wealth, poison into plant food, and chaos into sustainable productivity.

Master pH Control in Your Aquaponics System: The Intermediate Grower's Guide to Preventing System Crashes

Fri, 16 May 2025 00:00:00 +0000

You check your pH meter and your heart sinks. Yesterday it was 7.0—perfect. Today it’s 6.2 and dropping. Your fish are showing signs of stress, your plants are struggling to uptake nutrients, and you’re watching weeks of careful system management unravel in real time. Welcome to the pH rollercoaster that separates successful aquaponics growers from those who give up in frustration.

As an intermediate aquaponics grower, you’ve moved beyond the basic “keep it between 6.0 and 7.0” advice. You understand that pH isn’t just a number to maintain—it’s the master control that determines nutrient availability, bacterial health, fish welfare, and plant productivity. But knowing it’s important and actually managing it successfully are two very different challenges.

Maximizing Efficiency: The Power of Customizable Operations Checklists for Project Planning and Documentation

Sat, 04 Mar 2023 00:00:00 +0000

Have you ever been part of a group project that ended up being a disaster? Maybe things were forgotten or tasks were duplicated, causing confusion and wasted time. Well, there’s a tool that can help avoid these problems and make project planning and documentation a breeze: customizable operations checklists.

Customizable operations checklists are like a to-do list that outlines all the tasks that need to be completed for a project. The beauty of a customizable checklist is that it can be tailored to fit the specific needs of your project or team. For example, if you’re planning a school event, your checklist might include tasks like reserving a space, ordering food, and creating flyers. But if you’re working on a science project, your checklist might include tasks like researching, conducting experiments, and writing a report.

Feeding Cities: The Impact of Urbanization on Food Production and Solutions for Sustainable Growth

Fri, 24 Feb 2023 00:00:00 +0000

Urbanization, or the process of cities becoming more populated and developed, has a significant impact on food production. As more people move to cities, the rural labor force that is responsible for producing much of the world’s food is shrinking. This shift in population also presents challenges for producing food in urban areas, where space is limited and often expensive. To address these challenges, there is a growing need for localized food production facilities, such as rooftop gardens and vertical farms. These facilities allow for fresh produce to be grown and harvested within the city limits, reducing the need for long-distance transportation and the associated environmental impact.

Aquaponics AI is now FarmHub® - A new chapter in our journey

Thu, 23 Feb 2023 00:00:00 +0000

We have some big news 🎉

It’s fascinating to learn that in certain cultures, changing one’s name is considered a highly significant milestone in life. This practice entails a ceremonial event that holds deep symbolic meaning, as it represents the individual’s identity and transformation, signifying the start of a fresh chapter in their personal journey.

These are the moments that make it all worthwhile, indicating that you have achieved a goal, and are ready to take on new challenges.

6 Ways to Support Small-Scale Fishing Communities for Sustainable Food Systems

Mon, 20 Feb 2023 00:00:00 +0000

Small-scale fisheries play an essential role in food security and nutrition, providing employment for over 90 percent of the approximately 120 million people employed in the industry. However, these fishing communities are often overlooked, and their actors tend not to be involved in the decision-making processes that influence their lives and future. Here are six ways to support small-scale fishing communities:

Enable social organization: Efforts should be made to enable social organization among fishworkers to strengthen their voice. This will help to ensure that they are involved in the decision-making processes that affect their livelihoods.

Feeding the World: Challenges and Solutions for a Resilient Global Food System

Mon, 20 Feb 2023 00:00:00 +0000

The Resilience and Stability in the Global Food System

The global food system refers to the complex network of actors, processes, and resources involved in producing, distributing, and consuming food across the world. The system is under pressure due to a variety of factors, including demand-supply imbalances, deteriorating environmental conditions, and health risks such as zoonotic diseases. In this article, we will explore these challenges and potential solutions to increase the resilience and stability of the global food system.

Greening Agriculture: Solutions for a Sustainable Future

Mon, 20 Feb 2023 00:00:00 +0000

Agriculture is the backbone of the world’s food supply, but it is facing numerous environmental challenges that threaten food production and food security. Climate change, pollution, loss of biodiversity, and degradation of arable lands are some of the critical issues affecting agriculture. The good news is that there are several solutions that can help address these challenges. From sustainable production methods to more efficient supply chains and nutrition-oriented agriculture, we have the power to create a more sustainable food system. In this article, we will explore some of the ways we can address environmental challenges in agriculture and create a more sustainable food future.

The Global Food Security Challenge

Sat, 21 Jan 2023 00:00:00 +0000

Feeding the World: 4 Solutions for Sustainable Food Production

The global population is expected to reach 10 billion by 2050, and with this growth comes the challenge of feeding an additional 2 billion people. Sustainable food production is critical to meeting this challenge, and technological advances and more efficient food supply chains can play a significant role. Here are five solutions for increasing food production while addressing environmental challenges:

Regenerative Agriculture

Regenerative agriculture is an approach that focuses on improving soil health and promoting biodiversity, while also reducing greenhouse gas emissions. This approach can increase food production while minimizing environmental damage. Some of the practices involved in regenerative agriculture include cover cropping, crop rotation, and reduced tillage.

How a Customized Operations Checklist Can Help Your Team Make Better Decisions

Wed, 18 Jan 2023 00:00:00 +0000

Have you ever been part of a team that has to make important decisions, but it feels like the process is long and disorganized? If so, you might want to consider using a customized operations checklist to streamline your decision-making processes. In this article, we’ll explain what a customized operations checklist is and how it can help your team make better decisions.

First of all, what is a customized operations checklist? It’s a document that lists all the steps your team needs to take to complete a task or make a decision. For example, if your team is working on a project, the checklist might include steps like “Define the project scope,” “Assign roles and responsibilities,” and “Create a timeline.” By creating a customized checklist, your team can make sure that everyone is on the same page and that no steps are missed.

From Fish to Greens: Discover the Sustainable Solution of Aquaponics for Feeding the World

Mon, 02 Jan 2023 00:00:00 +0000

As the world population continues to grow, we face a critical challenge of how to provide enough food to feed everyone in a sustainable and environmentally friendly way. According to the United Nations Millennium Development Goals (MDGs), we need to eradicate extreme poverty and hunger, achieve universal primary education, and promote gender equality, among other goals, by 2030. Aquaponics is a potential solution to help achieve these goals by providing a sustainable and efficient method of food production.

Meet Maia: The Sensor Inspired by Jordanian Youth

Wed, 17 Aug 2022 00:00:00 +0000

Not many of you will know this, but our early beginnings as a company were rooted deep in the heart of the Middle East.

We created aquaponic farms that impacted communities by decentralizing/localizing the food supply chain, improving the nutrients of food, providing jobs, and transforming how we view food.

In this story of liberation, we found an amazing center for youth with disabilities. This center helps youth with various disabilities get invaluable workforce training and personal development support.

Russell Henry joins us as our resident Marketing Advisor

Wed, 17 Aug 2022 00:00:00 +0000

FarmHub is excited to announce Russell Henry as our new Marketing Advisor!

Russell is the founder of HDC digital and has somehow managed to wrestle 3 young boys while animating and designing buildings and digital media. His family is inspirationally sustainable, even in the midst of the chaos of daily life. He is ready to take Aquaponics to the next level as an industry.

It takes fresh eyes to bring new styles of marketing, inspiration and direction to an industry. Russell is going to help us get there. It’s going to be fun. Thanks Russell.

Joe Pate joins FarmHub as our Scientific Advisor

Tue, 22 Feb 2022 00:00:00 +0000

FarmHub is excited to announce Joe Pate as our new Scientific Advisor!

Joe Pate is the founder of Regen Aquaculture and has lots of experience installing farms, running commerical systems, and dealing with just about every aspect of designing productive and regenerative farms.

We’re very excited about what this means for you, our customers. We are preparing trainings, insights, calculators, tools, resources and so much more. Our goal is to make sure you have everything you need to scale and unleash your farm. We believe that Joe can help us do this. Thanks Joe.

The Secret Behind Choosing Necessary Technology that Supports Your FarmOps

Wed, 08 Dec 2021 00:00:00 +0000

What are the most common sensors at hydroponic farms? What sensor should I buy for my aquaponics system? What parameters do you monitor in an aquaponics system?

These are all pressing & valid questions. What we want to look at today is a thought framework that can help you answer all of these questions and more.

It does require that you want to think about the situation, your goals, and the future of your farm. If you’re not interested in that, please feel free to stop here.

Analyzing Your Aquaponics System with the Data Explorer

Mon, 08 Nov 2021 00:00:00 +0000

Visualizing data has forever been challenging– and the process of wrangling all your data can leave you super frustrated. I would imagine that is the reason most people don’t like gathering data. Well, those days are over.

We are proud to release the brand new Data Explorer! A new feature on the FarmHub farming dashboard equipping you with the power to compare your notebooks and unlock insights from your farm.

We focus on consolidating all your notebooks from across your farm, sensor data, brix tests, harvesting logs, and bring it all to the powerful charts so you can compare, plot, and plan your steps to domination 🔥.

Scaling Your Aquaponics System Design & Consulting Business

Wed, 03 Nov 2021 00:00:00 +0000

Whether your working in Aquaponics, Hydroponics, or Aquaculture, you’re going to want to ensure that your customers are long term advocates for your services.

As a consultant, your advice goes a long way to ensuring their success.

As a system designer, you know that once a system is built there are still things that go wrong and TONS of things that are learned along the way.

This raises the question: How do you ensure customer success when they’re far away and out of touch? You’ve just invested time, money, resources, and information into their success, but now it is up to them to implement it and one of two things can happen:

Why Grow Using Aquaponic Systems?

Mon, 01 Nov 2021 00:00:00 +0000

Aquaponic and Aquaculture

Aquaculture, and subsequently aquaponics, is a major market opportunity available for domestic seafood producers. According to the 2019 Fisheries of the United States Report, seafood accounted for a 16.8-billion-dollar trade deficit in the United States, which is second only to oil and natural gas. This shocking statistic reflects a lack of domestic fish production and an over-reliance on wild fish populations.

Fish consumption in North America is expected to increase by 20% in the next 20 years. Data trends illustrate a growing need to further develop and refine fish farming habits if the supply is ever to meet future demands. The Global Aquaculture Alliance predicts that “62% of food fish will come from aquaculture by 2030”. Domestic fish production must increase to provide local and national food security, more sustainable food solutions, and healthier and more affordable protein options. Increased aquaponic system production can help empower local communities, provide educational opportunities, and promote healthier lifestyles.

Partnering with MMI Labs to bring lab testing to aquaponic, hydroponic and aquaculture systems

Thu, 28 Oct 2021 00:00:00 +0000

Aquaponics systems thrive or die based on their ability to handle nature’s challenges.

Nature’s challenges include balancing temperature, pH, oxygen-level, nutrients, nitrogen and alkalinity. An efficient approach to overcoming these challenges is through laboratory testing.

This is where MMI Labs comes in to help you optimize your system’s performance before things get out of hand. You don’t need to purchase equipment or chemicals because the lab does it for you. The best part is that they take care of the leg work involved with testing and provide simple-to-understand analytics.

Tracking Fish Weight, Length and Growth in Aquaponic Systems

Tue, 26 Oct 2021 00:00:00 +0000

Aquaponic systems require producers to track fish, plant, and system data. These components work together and depend upon each other to form a successful aquaponic operation. Specific factors while monitoring fish are tracking weight and length. Tracking these averages of a fish class is important because the measurements are an indicator of fish and system wellbeing. Other reasons for tracking these measurements include health indications, known growth rates, and business planning. **Tracking weights and lengths helps producers streamline their systems, plan more effectively for future seasons, and grow more efficiently. **

What are lab tests and how can I use them in my aquaponics system?

Fri, 22 Oct 2021 00:00:00 +0000

You will most likely be farming your aquaponics, hydroponics or aquaculture system for a few years before you enter the world of lab tests. It should absolutely be sooner.

But there are all these reasons why we don’t reach out to labs…

Top reasons we don’t reach out to labs

1. Which lab tests are necessary?

In your system you will always want to do a water quality test. This will tell you the contents and nutrients of your water which is valuable if you want to know what is bioavailable for your plants and bacteria. The awesome results of these tests will probably include a combination of the following:

Using Aquaponics for Chemistry, Biology, Physics, Plumbing, Carpentry and all aspects of Business!

Thu, 21 Oct 2021 12:40:00 +0000

23 years of offering Aquaponic 101 workshops to teachers! David Cline of Auburn University’s joins us from the E. W. Shell Fisheries Learning Center in Alabama. He’s passionate about education and sharing innovative ways to explore STEM through Aquaponics. Jump in and learn more about how aquaponics make an excellent teaching tool and how you can even do it yourself at home ( https://www.youtube.com/user/clinedj1).

David Cline of Auburn University is an Associate Extension Professor at the School of Fisheries, Aquaculture and Aquatic Sciences.

Using Aquaponics for Chemistry, Biology, Physics, Plumbing, Carpentry and all aspects of Business!

Thu, 21 Oct 2021 00:00:00 +0000

David Cline of Auburn University is an Associate Extension Professor at the School of Fisheries, Aquaculture and Aquatic Sciences.

Aquaponic Systems Utilize the Soil Food Web to Grow Healthy Crops

Sun, 17 Oct 2021 00:00:00 +0000

Brian Filipowich*, Sydni Schramm, Josh Pyle, Kevin Savage, Gary Delanoy, Janelle Hager, and Eddie Beuerlein

Summary of Research

1. Where does the soil food web live in a bioponic system?

Microbes aggregate on all surfaces within a bioponic system and suspended in the water column.
Roots are a hotspot of microbial activity in both bioponic systems and in soil.
Micro niches within the systems provide bacteria with ideal conditions for growth.

Nutrient Exposure Rates and Mastering Multicrop Systems in Commercial Aquaponics with Arvind Vinkat

Thu, 14 Oct 2021 12:37:00 +0000

How do you make an agricultural business using aquaponics sustainable for the long term? Arvind Vinkat, founder of Water Farmers, shares some fresh insights on nutrient exposure rates and how to think with water delivery to crops in a commercial setting.

Arvind is a thought leader in commercial aquaponics and has built many large-scale commercial aquaponics in multiple locations around the world.

Learn More

https://waterfarmers.ca/

#commercial #aquaponics #agribusiness #nutrients

System Cycling and Nutrient Uptake in Aquaponics

Thu, 14 Oct 2021 00:00:00 +0000

Nutrients are substances that nourish plants and animals by providing energy for growth and maintaining life. Individual plant and animal species require different nutrients to thrive. In aquaponic systems, fish receive essential nutrients from specially chosen, crafted, and stored food. Companies specialize in producing food for various species such as trout, salmon, catfish, and tilapia. Alternatively, plants in aquaponic systems rely on bacteria to transform fish waste into nutrients. The plants absorb the nutrients out of the water, thereby clarifying the water before it circulates back to the fish tank.

Importance of Following Standard Operating Procedures at your Aquaponic Farm

Sun, 10 Oct 2021 00:00:00 +0000

Protocols are set, followed, and enforced for a reason - to protect you, your farm, and the plants and animals you rear. Disregarding protocols or selectively choosing which practices to follow can lead to negative ramifications. These consequences can affect your entire operation and potentially result in crop and fish loss.

Standard operating procedures (SOPs) ensure that farms run smoothly and that all employees, volunteers, and workers are on the same page. Everyone will have the same, standardized response to situations. This standardization helps keep systems running consistently, allows for cleaner and more accurate data collection, and allows a producer to act proactively, not reactively. Key support for following farm maintenance schedules, standard operating procedures, and activity logs include biosecurity, system functionality, and human health concerns.

Next Steps and Future Industry Opportunities for Aquaponics in Mineral Delivery & Feeding Microbes

Thu, 07 Oct 2021 12:36:00 +0000

“I feed fish for a living”. In five minutes fish nutritionist Dr. Brown shares how we need to know the nutrient requirements of the target species and how feed inputs are critical to a healthy fish.

In Aquaponics we need to feed the fish, bacteria and plants. Jump in and learn more from his experience and how fish nutrition and adjusting the challenge of mineral deficiencies is key in an Aquaponic system.

Aquaponic Software and Mobile Application Feature Highlights

Mon, 04 Oct 2021 00:00:00 +0000

Aquaponic Software Features

Hi there! We want to highlight and share with you some features found in our platform. As Aquaponic practitioners we’re working on transforming how the world views food production and food security. We also grow awesome nutrient-rich crops, healthy fish and enjoy innovating within our grow spaces. Yet, we still need to understand more. Our community can only grow and expand if we understand our systems more, have better diagnostics, and have clear insights into the workings of our farms. This is exactly what data helps us do.

Joe Pate Wants To Feed ALL of Nature (Not Just People) With Aquaponics

Thu, 30 Sep 2021 12:35:00 +0000

George “Joe” Pate is a leading aquaponic consultant and the founder of Regenerative Ecosystems- an agricultural consulting company specializing in the research, development, and implementation of regenerative agriculture practices and bio-technologies.

Regen Aquaculture is their branch dedicated to Regenerative Aquaculture Systems like Aquaponics.

Like many of us, Joe has experienced firsthand the consequences of conventional agricultural systems. Watching common practices deplete life in our soils, waterways, skies, increase farmers’ hardships, and produce poor quality ‘food’, which has led to a pandemic of health issues.

Common Problems in Aquaponic Systems

Thu, 30 Sep 2021 00:00:00 +0000

Aquaponics combines hydroponics and aquaculture to create a more sustainable and efficient farming process. Fish and plants are reared together in systems that share water. The fish generate ammonia waste that bacteria transfix into a nitrogen product that the plants can absorb and use for food. Aquaponic systems are scientifically complex and must be properly monitored and maintained to ensure success. As a technology company we offer solutions to issues commonly faced by aquaponic growers. These issues fall under the umbrella of system planning decisions, data collection, storage, and analysis, and system maintenance choices.

Indoor Aquaponics Farm Producing 3,500 Heads of Lettuce per WEEK for local students!

Thu, 23 Sep 2021 12:34:00 +0000

Andrew Neighbour has a vision to show the viability and powerful aspects of Aquaponics right in Santa Fe. He’s driven by the need to grow and consume locally as well as inspire the next generation, policy makers, and consumers to invest in Aquaponics education.

Learn More

https://www.facebook.com/desertverdefarm/

http://desertverdefarm.com/

The Importance of Tracking Water Temperatures in Aquaponic Systems

Thu, 23 Sep 2021 00:00:00 +0000

Water is the lifeblood of an aquaponic system. Therefore proper monitoring and insights into water temperature is crucial to maintaining water quality, fish and plant health. Water attributes to monitor include ammonia levels, PH, dissolved oxygen (DO), and water temperature. Monitoring and regulating the temperatures outside of and within your system are key to running a successful aquaponic operation. Plants and fish in aquaponic systems must live within certain temperature thresholds for biological reasons, to optimize growth patterns, and to limit the spread of disease.

Facing the World's Problems with Aquaponics with Sam Fleming at 100 Gardens

Thu, 16 Sep 2021 12:33:00 +0000

“The best way to do it, the best way to build your confidence is to just get started”. Sam Fleming is the Executive Director of 100 Gardens. They install and implement aquaponics programs in schools and correctional centers.

Through aquaponics and their programs, 100 Gardens understand students can be a catalyst of change. They hope to impact tens of thousands of students and create a city full of smarter, healthier and more compassionate humans. Sign us up for that!

Rachel Fogle is Unlocking Potential with Aquaponics in STEM Education

Thu, 09 Sep 2021 12:31:00 +0000

Harrisburg University of Science & Technology is killing it when it comes to being a STEM focused university. Aquaponics is one of the ways students are involved in experiential learning and internship opportunities preparing students for their career paths.

Dr. Rachel Fogle is an Associate Professor of Biological Sciences at Harrisburg University of Science and Technology. She is also the lead and coordinator of the Aquaponics Initiatives.

Jump in and hear about how diverse disciplines like biology, technology, and environmental science directly relates to cutting edge Aquaponic research and innovation at Harrisburg University.

What is Hydroponics?

Thu, 02 Sep 2021 00:00:00 +0000

The ability to produce higher yields than traditional, soil-based agriculture. Allowing food to be grown and consumed in areas of the world that cannot support crops in the soil.
Eliminating the need for massive pesticide use (considering most pests live in the soil), effectively making our air, water, soil, and food cleaner.
Popularizing indoor agriculture in areas where it would be difficult, if not impossible to grow crops outdoors (deserts, high altitudes, cold regions).
Food being grown indoors allows for a more steady supply year-round. This is an important aspect of food security for many developing countries that rely on imports from outside their borders.
Hydroponic systems can also be run by a single operator in the comfort of their own home. In parts of the world where natural light levels are low, hydroponic systems can provide a level of artificial lighting that just isn’t possible outside.
Finally and most importantly, providing the highest standard of living for farmers with a high level of efficiency.

Typically farmland is in short supply and expensive. Hydroponics allows for more space to grow crops and provides an opportunity for commercial farming that would normally not be financially feasible on land without expanding the size of the farm or buying more land and paying higher costs.

A brief history of Hydroponics, Next-Gen Farming, and Soil-less Farming

Fri, 27 Aug 2021 00:00:00 +0000

Now, Hydroponics has many applications. It is used worldwide to grow plants on land or in water without dirt or soils, for both commercial and home use. The roots of the plant do not contact the growing medium or soil, but instead reside in a solution containing all of the nutrients that are required for plant growth.

The environmental conditions within which hydroponic plants are grown can be controlled to create optimal growing environments. Hydroponics is used to grow greenhouse crops on a year-round basis and to produce healthy food economically.

Charlie Shultz on the Importance of Remineralization of Solid Waste in Aquaponics

Thu, 26 Aug 2021 12:28:00 +0000

Charlie Schultz on why he got into Aquaponics! He is one of the leading voices and researchers for Aquaponics and has a passion for inspiring others to invest in the Aquaponics world.

Waste management, fish farming, recycling, and remineralizing waste are essential concepts in Aquaponics and Charlie “breaks it down” for us :P

Learn More

Charlie Shultz

Lead Faculty at Controlled Environment Agriculture

School of Trades, Technology, Sustainability and Professional Studies

Tracking Fish Health to Boost System Health & Profitability in Aquaponics

Wed, 25 Aug 2021 00:00:00 +0000

Aquaponic systems require growers to track fish, plant, and system data. These components work together and depend upon each other to form a successful aquaponic operation. Specific factors within monitoring fish to track are weights and lengths. Tracking these averages of a fish class is important because measurements are an indicator of fish and system wellbeing. Other reasons for tracking these measurements include health indications, known growth rates, and business planning.

Next-gen Aquaponics by Upgrading Your Filtration & Lighting by Rob Tolette at the Aquaponic Source

Thu, 19 Aug 2021 12:26:00 +0000

Rob Tolette at the Aquaponic Source ’nerds out’ with us on two things he’s passionate about in aquaponics filtration and lighting. He’s Director of Sales and Product Development at The Aquaponic Source and shares with us why he sees filtration as the most important part of an aquaponic system and figuring out a way to deal with the waste from the fish.

How are you doing filtration? We’d love to hear below - please share some details on your system and types of filtration you are using. And lights, anyone using grow lights?

Limitations of Using an Excel Spreadsheet for Tracking Aquaponics Data

Wed, 18 Aug 2021 00:00:00 +0000

Proper monitoring and data collection strategies are imperative to running a successful aquaponic operation. Maintaining records is paramount to understanding trends within your systems and potential preventative measures you can take to avoid die-offs. As a social-impact agriculture technology business we are excited about powering and liberating the heroes of next-gen aquaponic food production with technology. We’re growers ourselves, so we know it can be hard to keep track of all the data from your sensors, paper notes and the minds of your teammates ;). That’s why we created this very platform – so you can consolidate everything into one place!

Monitoring Fish Health in Aquaponics Systems & Aquaculture Farms

Fri, 13 Aug 2021 00:00:00 +0000

Aquaculture, according to the National Oceanic and Atmospheric Administration, is the “breeding, rearing, and harvesting of fish, shellfish, algae, and other organisms in all types of water environments”. Aquaponics, a subset of aquaculture, is where fish and plants are grown together using recirculating water.

Maintaining fish health is imperative to running a successful aquaponic operation. According to Ruth Francis-Floyd from the University of Florida, “fish health management is a term used in aquaculture to describe management practices which are designed to prevent fish disease. Once fish get sick, it can be difficult to salvage them”. The premise of fish health management is preventative and proactive, not reactive. Maintaining detailed water quality records and observing your fish will give you the best chance of limiting disease in your systems.

Steven Hedlund of the Global Aquaculture Alliance on the seafood industry, sustainability & agtech

Thu, 05 Aug 2021 12:21:00 +0000

Steven Hedlund is a veteran in the seafood industry with 20 years of experience in the industry. He has a deep understanding of the seafood value chain and sustainable seafood programs.

We sit down in and talk about the Global Aquaculture Alliance and their mission of feeding the world through responsible aquaculture. It’s exciting to hear the amount of investment being put into new aquaculture production systems and sustainable practices, how aquaponic growers can be more responsible on the aquaculture side and touch base on their aquaculture certification program (Best Aquaculture Practices). Jump in and hear about innovations in fish nutrition and the future of sustainable aquaculture!

FarmHub Sponsors the 2021 Aquaponics Conference in OKC

Mon, 02 Aug 2021 00:00:00 +0000

“I’m want to start an aquaponics farm, but don’t know where to begin.”

Well, the Aquaponics Association Conference is the world’s largest conference for people interested in starting or running an aquaponics business. Attendees will learn everything they need to know about the business of aquaponics from experts in the field.

That’s why we’ve partnered with the Association to put on this awesome conference! We’re proud to support such awesome initiatives. We’re also offering a special discount code for anyone who attends this year’s Aquaponics Conference! Come to our digital booth to get your awesome coupon code.

Learning Aquaponics at Santa Fe Community College

Sat, 31 Jul 2021 00:00:00 +0000

These lettuce seedlings sitting in front of me took three years to grow. Well in truth, they are two weeks old, but in reality, to build the farm in which they now grow took what seems a lifetime to get off the ground.

The first seed was sown a long time ago when a colleague and I were making a film about the sustainability programs at Santa Fe Community College’s School of Trades, Advanced Technologies and Sustainability in Santa Fe, NM.

Meet Sam Fleming – Co-founder of 100 Gardens & Aquaponic Guru

Thu, 29 Jul 2021 12:13:00 +0000

Sam Fleming is the Executive Director 100 Gardens. The organization has developed curricula and trained teachers so they can teach students about sustainable practices like aquaponics farming. With 14 schools and two prisons already on board, we are confident this innovative program will help provide healthy produce for future generations!

When not playing in aquaponics land, Sam plays guitar in the rock and roll band TYGER.

Learn More

www.100gardens.org

www.homegrowntomato.live

Studying Aquaponics at Kentucky State University - A Review by Joe Pate

Sun, 20 Jun 2021 00:00:00 +0000

Kentucky State University (KYSU or KSU) is a historically black college and university founded in 1886 in Frankfort, Kentucky. In 1890 KYSU became a land-grant university and has continued to grow into an outstanding school and home to one of the best freshwater aquaculture programs in the country.

I remember the first time I came to KYSU, I was studying at Berea College, an hour south of KYSU when I had the opportunity to attend an aquaponic workshop hosted by KYSU. During this workshop, I had the chance to learn from Charlie Shultz and Dr. James Tidwell, experts in aquaponics and aquaculture, and tour their facilities.

Industry Leaders Talking Tech & Food Innovation in Dubai

Thu, 20 May 2021 00:00:00 +0000

AgTech’s finest will be gathering at Step Conference FoodX Summit to talk about the latest trends and disruptive technologies that have changed the way we produce and consume food.

FarmHub CEO & Co-founder, Jonathan Reyes, will be speaking on the exciting and untapped potential of controlled environment agriculture in the region. Get your tickets to learn how the aquaponic industry is evolving to meet the world’s most pressing needs.

Join today!

Jonathan Reyes on Aquaponics & AgTech for the MENA region

Fri, 23 Apr 2021 00:00:00 +0000

Our CEO, Jonathan Reyes, is doing a FREE webinar sponsored by the U.S. Embassy Baghdad and IREX on AgTech and Aquaponics in the context of global & sustainable food systems. It will be simultaneously translated to Arabic and Kurdish.

1.1 Definition

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Aquaponics (AP) is a self-supporting food production system that combines recirculating aquaculture with plant culture in the absence of soil (hydroponics). High-volume fish production results in nutrient- rich water that can be used to provide nutrients for plant cultivation.

Source: Janelle Hager, Leigh Ann Bright, Josh Dusci, James Tidwell. 2021. Kentucky State University. Aquaponics Production Manual: A Practical Handbook for Growers.

1.2 Context

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Development of aquaponic systems resulted from the need to reduce costs associated with high-nutrient effluent discharged from recirculating aquaculture systems (RAS). Known for intensive aquaculture, RAS can produce large quantities of fish in a small volume of water. Some water is discharged and replaced in the system over time, as solid waste and toxic nitrogen by-products (ammonia (NH3-N), nitrite (NO2-N), and nitrate (NO3-N)) build up. Concentrated discharge from intensive aquaculture is a barrier to positive consumer perception of aquaculture. However, these accumulated nutrients can be similar in composition and concentration to hydroponic nutrient solutions and often exist in the form preferred by plants (Rackocy et al. 2006). Combining these two production technologies provides an efficient and sustainable method of growing fish and produce.

1.3 Importance

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Hydroponics and intensive RAS each have ecological and economical drawbacks when considered individually. Hydroponic crops rely on chemical fertilizers that are expensive, hard to source, and in some cases are derived from rapidly disappearing natural resources. In intensive fish production, concentrated wastes are generated (i.e. effluent) that require expensive treatment methods, leading to poor consumer perception regarding environmental impacts. The high initial investment may be prohibitive to potential producers, as well. Aquaponics provides the opportunity to utilize aquaculture effluent while growing plants with a sustainable, cost-effective, and non-chemical nutrient source.

1.4 System Types

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There are two main types of AP systems, coupled and decoupled. The coupled approach is widely used and is based on feeding the system known nutrient-input amounts/values. The support for plant growth and bacterial consumption (in the biofilter) typically come from commercial fish food and must be factored into system input requirements. These ratios are used to ensure that toxic waste products from fish effluent do not build up (due to an insufficient biofilter), excess nitrates do not occur (from not enough plants), and nitrate deficiencies do not develop (from an excess of plants). Recommended operating ratios for aquaponic systems will be covered in the Structure and Design section.

10.1 Economic

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There is relatively little information available on the economics of aquaponics, likely due to a lack of successful commercial production before 2014. Based on information summarized in Engle (2015) and Heidemann and Woods (2015), aquaponics profitability is achievable depending on geographic location, climate, initial investment, production cost, market demand, and consumer preference for goods.

Production in USDA Zones 7-13 are typically most profitable in the U.S. due to reduced risk of losses associated with cold weather, power outages, and utility costs (Love et al. 2015). Another production factor is labor costs, which have been estimated at 46% of total operating cost and 40% of total annual cost (Tokunaga et al. 2015). Reduced delivery travel costs are associated with aquaponic production due to the capability of suburban and urban production.

10.2 Marketing

Thu, 22 Apr 2021 00:00:00 +0000

The most difficult aspect of any aquaponics operation is developing a realistic and practical marketing scheme (Engle 2015). Location is key for marketing because location determines what is in demand and the size of the market. Having close access to multiple cities significantly increases the market size as well as market demographics and in turn increases demand for product. If the location is within a remote area such as an island, then the market price for the product will be much higher compared to a location in an easily accessible area (Engle 2015). Since aquaponics production can be done year-round, growing and selling produce that is locally considered “out of season” can help achieve a higher price point. Offering a variety of niche crops such as microgreens, house plants, and herbs holds much potential to increase the market as well as profits.

11.1 Organic Certification

Thu, 22 Apr 2021 00:00:00 +0000

Organic food sales in the United States rose by 5.9% in 2018, totaling $47.9 billion dollars. It is no surprise that aquaponic farmers want the organic label to bolster their marketing and sales, and equally no surprise that soil-based farmers do not want their selling power to be diluted. The heart of organic production is cultivating soil, so how can produce be certified organic if there is no soil? In 2015, a taskforce was assembled consisting of individuals representing both the soil-based organic industry and the hydroponic and aquaponic communities. The goal was to describe hydroponic and aquaponic systems and practices, examine how hydroponics and aquaponics align or conflict with USDA organic regulations, support their decisions with science, and explore alternatives. At its 2017 fall meeting, the National Organic Standards Board (NOSB) voted 8-7 against a proposal to prohibit hydroponic and aquaponic production in organic agriculture. Although aeroponics is prohibited, both hydroponics and aquaponics remain eligible for organic certification, while the USDA considers the NOSB decision. While aquaponics lends itself to a more sustainable growing methods, only OMRI approved items can be used during production. This prohibits the use of rockwool, hydroxide bases, chelated iron, and other common tools of the trade. Currently, only 17 of 80 certifiers will assist aquaponic farms with organic certification.

11.2 Certified Naturally Grown (CNG)

Thu, 22 Apr 2021 00:00:00 +0000

Known as the “grassroots alternative to organic,” CNG certification follows organic standards but focuses on growers who sell directly to the consumer. CNG farmers are restricted from using synt8hetic herbicides, pesticides, fertilizers, or genetically modified organisms (GMOs). Farms with CNG certification undergo an annual inspection and pay an annual fee. Inspections can be conducted by other CNG farmers, Extension agents, master gardeners, or other qualified personnel. Sections of the CNG standards for aquaponics can be found at (http://www.cngfarming.org/aquaponics_standards)

11.3 Good Agriculture Practices (GAP)

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Good Agriculture Practices (GAPs) are specific methods that, when applied to agriculture, create food for consumers or further processing that is safe and wholesome. Currently a voluntary certification, the Food Safety Modernization Act (FSMA), will require farms to comply with food safety and security measures outlined in the document. In 2011, the Produce GAPs Harmonized Food Safety Standards was released, which require producers to meet standards for biosecurity, sanitation, worker training, and documentation. Information on Produce GAP can be found at (http://www.ams.usda.gov/services/).

11.4 Hazard Analysis and Critical Control Point (HACCP)

Thu, 22 Apr 2021 00:00:00 +0000

HACCP is a management system in which food safety is addressed through the analysis and control of biological, chemical, and physical hazards from raw material production, procurement and handling to manufacturing, distribution, and consumption of the finished product.

Source: Janelle Hager, Leigh Ann Bright, Josh Dusci, James Tidwell. 2021. Kentucky State University. Aquaponics Production Manual: A Practical Handbook for Growers.

11.5 Standard Operating Procedures (SOPs) and HACCP

Thu, 22 Apr 2021 00:00:00 +0000

Determining risk factors in the production, processing, sale, and consumption of food items involves HACCP, SOPs, and Sanitation SOPs (SSOPs). Developing a protocol for each step of the operation and providing employee training is essential to provide a safe food product. The following are examples of how HACCP, SOPs, and SSOPs work in conjunction.

Chemical: Use of cleaner on surfaces. Could it be a hazard? Yes, but in our SSOP we have a second rinse step to remove residue, so it is not a CCP because it is handled someplace else in the plans.

11.6 Best Aquaculture Practices (BAPs)

Thu, 22 Apr 2021 00:00:00 +0000

Based on BAPs, the five pillars of responsible aquaculture are environmental responsibility, animal health and welfare, food safety, social responsibility, and traceability. Critical requirement include record keeping and traceability, worker safety and hygiene, and biosecurity. More information on BAPs can be found at (http://www.bapcertification.org/)

Source: Janelle Hager, Leigh Ann Bright, Josh Dusci, James Tidwell. 2021. Kentucky State University. Aquaponics Production Manual: A Practical Handbook for Growers.

11.7 Propagation Permits

Thu, 22 Apr 2021 00:00:00 +0000

Commercial fisheries propagation permits are required by state wildlife agencies for culture and sale of aquatic organisms. Information provided includes the name and location of the business, water source, flooding likelihood, discharge information, how the brood stock was obtained, quantity and type of species produced, and the type of production system. Required information and cost of the permit will vary by state.

Source: Janelle Hager, Leigh Ann Bright, Josh Dusci, James Tidwell. 2021. Kentucky State University. Aquaponics Production Manual: A Practical Handbook for Growers.

12.1 Extension Publications and Talks

Thu, 22 Apr 2021 00:00:00 +0000

Ako, H. Year. How to build and operate a simple small-to-large scale aquaponics system. Center for Tropical and Subtropical Aquaculture Center Publication 161. Available: http://www.ctsa.org/files/publications/CTSA_aquaponicsHowTo.pdf (Accessed June 29, 2016)

Ako, H. and A. Baker. 2009. Small-Scale Lettuce Production with Hydroponics or Aquaponics. Sustainable Agriculture SA-2. College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. Available: http://fisheries.tamu.edu/files/2013/10/Small-Scale-Lettuce-Production-with-Hydroponics-or-Aquaponics.pdf (Accessed June 29, 2016)

Burden, D. J. and D. A. Pattillo. 2013. Aquaponics. Agriculture Marketing Resource Center. Available: http://www.agmrc.org/commodities-products/aquaculture/aquaponics/ (Accessed June 29, 2016)

12.2 Recommended Videos

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Danaher, J. 2015. Aquaponics – An Integrated Fish and Plant Production System. Southern Regional Aquaculture Center. http://www.ncrac.org/video/aquaponics-integrated-fish-and-plant-production-system (Accessed June 29, 2016)

Hager, J. V and Dusci, J. 2020. IBC Aquaponics: a step-by-step guide. http://www.youtube.com/watch?v=BwbvOMoU9oE

Pattillo, D. A. 2016. Aquaponics: How to Do It Yourself! North Central Regional Aquaculture Center Webinar Series. Accessed: http://www.ncrac.org/video/aquaponics-how-do-it-yourself (Accessed June 29, 2016)

Pattillo, D. A. 2013. Aquaponics System Design and Management. Iowa State University Extension. Available: https://connect.extension.iastate.edu/p5fba9a68a0/?launcher=false&fcsContent=true&pbMode=normal (Accessed June 29, 2016)

12.3 Resource Pages

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Agricultural Marketing Resource Center http://www.agmrc.org/

Aquaponics Association http://aquaponicsassociation.org/

Aquaponics Journal http://aquaponicsjournal.com

ATTRA National Center for Appropriate Technology https://attra.ncat.org/

Kentucky State University - Aquaculture Research Center http://www.ksuaquaculture.org/

Iowa State University Extension Online Store http://store.extension.iastate.edu/

Iowa State University Fisheries Extension http://www.nrem.iastate.edu/fisheries/

North Central Regional Aquaculture Center www.ncrac.org

Southern Regional Aquaculture Center – Aquaponics Publication Series https://srac-aquaponics.tamu.edu/

Sustainable Agriculture Research and Education Program http://www.sare.org/

USDA – National Agricultural Library http://www.nal.usda.gov/afsic/aquaponics University of Minnesota Aquaponics http://www.aquaponics.umn.edu/aquaponics-resources/

Texas A&M Aquaponics http://fisheries.tamu.edu/aquaponics/

Source: Janelle Hager, Leigh Ann Bright, Josh Dusci, James Tidwell. 2021. Kentucky State University. Aquaponics Production Manual: A Practical Handbook for Growers.

2.1 Fish Culture

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Fish tanks for aquaponics come in a wide range of shapes, sizes, and materials, with selection being largely based on culture species. The majority of large systems use round tanks that either have a flat- or cone-bottom. Use of tangential flow will prevent dead zones when used in round tanks (Figure 2). Cone-bottom tanks allow solids to concentrate at the bottom (in the cone) and be easily flushed from the system. Flat-bottom tanks are more widely available, but solids removal requires additional steps to ensure proper removal of organic material dispersed across the bottom of the tank.

2.2 Solids Filtration

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Effective solids filtration is a key component to a well-functioning system and potentially the most important aspect as it influences the efficiency of all other processes. Solids are mostly produced from uneaten feed, fish waste, and bacteria biofilms (classified as suspended solids) (Timmons and Ebeling 2013). If waste is not removed, it can settle on plant roots (preventing uptake of nutrients), collect in areas of low water flow (resulting in poor water quality), cause the build-up of noxious gas, and clog pipes (preventing sufficient water flow) (Somerville et al. 2014).

2.3 Biological Filtration

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Biological filtration refers to the breakdown of ammonia (NH3 and NH4+) into nitrite (NO2) and then further into nitrate (NO3) by naturally occurring, nitrifying bacteria. These bacteria live on the surface area of media contained in a tank collectively called the biofilter. The process of converting ammonia to nitrate will be detailed in the section on water quality.

In RAS, the biofilter is designed to operate at low pressure. There is a dedicated tank filled with substrate like Kaldnes media, granular media, plastic balls, or other inert materials that have a large specific surface area or surface area of the media per unit volume. The higher the specific surface area, the more bacteria can grow on the media, translating to a higher ammonia removal capacity. Typical biofilter designs for RAS include trickle towers, submerged media, fluidized beds, sand filters, and static bed filter. In aquaponics, the biofilter can either be a separate unit or part of the system. In deep water culture (DWC), the plant trough walls, raft bottoms, and plant roots provide a significant surface area for nitrifying bacteria to colonize. Unlike RAS, the AP system itself typically provides ample surface area for bacteria to colonize, particularly for coupled systems that are appropriately sized. The nutrient film technique (NFT) system (see section below) is an exception, as only a thin layer of water is applied to the plants. If the biofilter is a separate unit, it should be located after the solids removal unit.

2.4 Plant Culture or Hydroponic Subsystem

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The hydroponic portion of the system encompasses the majority of the facility footprint. Three primary designs are used: media beds, deep water culture (DWC), and NFT.

Media-based systems: The design of media-based systems, sometimes called flood-and- drain, is fairly straight forward. A container filled with substrate is periodically flooded with water from the fish tank. Water then drains back to the sump (or fish tank) drawing oxygen into the substrate for plant roots and nitrifying bacteria. The media bed supports the plant as it grows and serves as a solids and biological filter (Figure 6). Due to relatively few components and ease of construction and operation, these systems are popular for hobbyists and in developing regions. However, it is uncommon to find commercial production using only media beds as they are less productive than other types discussed below. Rule of Thumb for media systems are detailed in Table 1.

2.5 Sump

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The sump is the lowest point of the system and where water collects to be distributed as needed throughout the system. Water quality samples can be taken here and amendments can be made without overwhelming the fish or hydroponic components. While not a requirement, the addition of a sump prevents the water level from changing in either the fish tank or hydroponic component. In other cases where safeguards are put in place, the fish tank or hydroponic component can be used as the sump.

3.1 Water Sources

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Sourcing water is an important consideration, as it directly impacts system management and performance. Typically, 1-3% of total system water is replaced per day depending on climate, time of year, and crops being produced (Somerville et al. 2014). Water is lost in the system through evaporation, transpiration into the plant, and through normal processes of splashing, cleaning, and harvesting.

Water with a salinity above 0.8 parts per thousand (ppt) are typically not suitable for aquaponic production as the majority of cultured plants do not tolerate even a small degree of salt (Shannon and Grieve 1998). Common aquaponic crops with a salinity tolerance include lettuce (0.83 – 2.8 ppt), kale (up to 7.4 ppt), Swiss chard (1.5 – 3.5 ppt), and tomatoes (up to 5.8 ppt) (Maggio et al. 2007, Shannon and Grieve 1998, Shannon et al. 2000). Even though some crops do show an ability to tolerate salt, growth is compromised at some point during production..

3.2 Disposal of Waste

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Recovery and digestion of fish effluent is more important in aquaponics than waste disposal. A large portion of feed is excreted as solid waste. Nutrients essential for plant growth are trapped within this concentrated slurry and should be recovered to reduce production costs and limit the need for nutrient supplementation. Recovery of these nutrients moves aquaponic production towards a zero-discharge system. Nutrients can be recovered through aerobic or anaerobic digestion of solids. Direct application of nutrients to crop land or composting sludge may be appropriate.

4.1 Suitable Species of Fish for Culture

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Unfortunately, not all fish species adapt well to tank culture, just as not all animal species adapt to being farm animals. Since fish are cold blooded, almost everything about their growth and health is influenced by temperature (see Tables 4 and 6 for details). The temperature of the culture water will partially dictate what species can or should be raised in your system. Other important factors will be how densely you intend to raise them and for what purpose or market. The rule of thumb for stocking density is 0.5 pound of fish weight per 1 gallon of water in grow out RAS. The following are considerations about what to grow for specific markets.

4.2 Species Overviews

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Tilapia: Tilapia (usually Oreochromis niloticus or the Nile tilapia) are the most cultured fish in aquaponic systems. They are tolerant of both crowding and relatively poor water quality conditions. They do best at water temperatures of 25-30°C. At temperatures < 24°C, their growth slows substantially, and they become susceptible to disease. They breed readily and abundantly. In fact, if using mixed sex fish, unintended spawning in the system can be a problem particularly in DWC beds where tilapia will consume all available plant roots. Monosex fish (all male) are available and preferred. Tilapia are widely accepted in the marketplace. If available, ethnic markets, which accept live or whole fish, should be considered. The tilapia is most efficient when grown to ¾-1 lb. in final weight. For processed products, such as fillets, tilapia must be raised to large sizes since they have low fillet yields (33% of body weight) compared to other species.

4.3 Fingerling Production and Supply

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Fingerlings for fish culture can either be obtained from a supplier or produced in-house. Availability, price, number of fingerlings needed, and level of expertise are the main factors that determine the method of choice. Type of species cultured, season, and location can also heavily influence the methods.

Supply: The best option for small-scale producers is to buy from a supplier. Suppliers should maintain detailed breeding records, use high-quality broodstock, and implement Best Aquaculture Practices (BAPs). In the case of fish fingerlings, cheaper is not always better.

4.4 Fish Stocking

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Fish culture should be well planned, as mismanagement of densities within the system can lead to issues with nutrient build-up/deficiencies, solids accumulation, water quality concerns, and poor fish health. Consider that aquaponic systems typically do not operate with a fish density exceeding 0.5 pounds/gallon. Three of the most common fish production plans are sequential rearing, stock splitting, and multiple rearing units.

Sequential Rearing: Sequential rearing involves one tank, containing multiple age-groups of fish (Rackocy et al. 2006), where the market-sized population is selectively harvested, and fingerlings are restocked in equal number. While this seems manageable, the continuous grading required can be stressful on remaining stock, leading to increased risk of disease and death. In addition, stunted fish remain in the system, consuming feed that will not yield any return for operation costs. Carnivorous fish are not well suited for this management strategy, as younger fish are susceptible to predation.

4.5 Plants

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Stocking and harvesting strategies can also be implemented in the hydroponic portion of the system. The three most common strategies are staggered cropping, batch cropping, and intercropping (Rackocy et al. 2006). Their implementation and success depend on geographic location (tropical or temperate regions), crop variety (leafy vs. fruiting crops), and market demand.

Aquaponic producers typically grow leafy green crops, which have a lower value per unit value and high yield. Lettuce, Swiss chard, kale, basil, and other herbs are typically ready for harvest between 3-5 weeks from transplanting (6-8 weeks from seed), resulting in a steady income stream. Fruiting plants like tomatoes, cucumbers, and peppers take 10-16 weeks to harvest, resulting in longer growing periods and lower yields, but they have a higher individual value. Producers often grow a variety of crops to diversify their markets and reach a number of consumer groups.

5.1 Formulated

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Formulated feeds are nutritionally complete pellets that are formulated for specific fish and life stage (Figure 15). Unlike other animal crops in agriculture, the nutritional needs of fish vary greatly among species for protein, fat, and carbohydrate inclusions. A carnivorous fish who eats at the top of its food chain, like a largemouth bass, requires a diet with high protein and low carbohydrates. On the other hand, omnivorous or herbivorous fish, like catfish or tilapia, require less protein and can tolerate higher levels of carbohydrate in their diets. This is important in aquaponics because the nutrient composition of the feed pellet drives the nutrient load available to the plants. As the fish feed is consumed and excreted by the fish, nutrients are released into the water as dissolved or solid particulates, which get circulated and used for plant growth. For example, feeds with a higher protein content will deliver a higher amount of total ammonia nitrogen (TAN) to the system, as nitrogen is primarily derived from the protein in the feed. The amount of TAN produced from a particular feed per day can be calculated using the following formula from Timmons and Ebeling (2013):

5.2 Supplemental

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A common question among small-scale and hobby aquaponic growers is if they can feed vegetable scraps, insects, or loose grains to their fish. These are known as supplemental diets and only meet part of the nutrient requirement of the fish. This is sometimes seen in traditional aquaculture practices in which fish are contained in large bodies of water where they can scavenge additional foods from the environment. Because aquaponics is a completely closed system, a complete diet must be fed. In addition, if fish must expend energy to scavenge for loose food or scraps, they are not growing at their full potential. Providing all their required nutrition in one, appropriately sized pellet allows the fish to convert more of that energy into growth, rather than using it to find food.

5.3 Alternative Diets

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Alternative diets are a great option to utilize bulk products that are a byproduct of another production system, non-traditional ingredients, or even agriculture scraps. These diets would be prepared on- site and would still be combined in a ratio to meet both the nutrient requirements of the fish and the plant crop. One area where this is seen is in the brewing of craft beer or spirits. The spent grains from the fermentation process (brewer’s grains) typically have a protein content high enough to be used in combination with another protein component, again dependent on the crops to be grown. Also utilized are refuse from animal processing plants, scraps from crop harvest, or even earthworm or other insect sources. One newer insect meal being used is black soldier fly larvae (BSFL). This is an especially good protein source because the larvae can be “gut-loaded,” or fed whatever precursor food would most benefit the fish consuming it, like foods high in Omega-3 fatty acids.

6.1 Dissolved Oxygen

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Oxygen is required at high levels by fish, plants, and bacteria. Oxygen content is quantified by the dissolved oxygen (DO) in water and is expressed as milligrams per liter (mg/L) (Somerville et al. 2014). The intensive nature of aquaponic systems requires oxygen supplementation. Oxygen can enter the system by agitation at the surface or by diffusers in the water column. Fish stocking density, number and type of plants, amount of organic solids, biological oxygen demand, and temperature are all factors that determine how much DO is needed (Rackocy et al. 2006, Wurts and Durborow 1992). DO and temperature have an important relationship. Oxygen is more soluble in cold water than it is in warm water, meaning that cold water can retain higher levels of dissolved oxygen than warm water. This is particularly important for producers raising warm water fish or operating in areas that experience high year-round or seasonal temperatures. It is recommended that dissolved oxygen be maintained between 5-8 mg/L. DO is difficult to measure, as meters can be expensive or hard to find. In this case, producers can purchase DO aquarium test kits or contact local Extension or universities for assistance.

6.2 Temperature

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Water temperature is more important in aquaponics than air temperature. Many water chemistry factors are affected by temperature, such as the amount of toxic ammonia (un-ionized) present and the solubility of oxygen. It also directly impacts the health and survival of both fish and plants. Fish are poikilothermic, or cold-blooded. This means that their body temperature is dependent on water temperature. At extreme temperature, fish will stop eating, becoming lethargic and susceptible to disease. In plants, high temperature can reduce the uptake of essential plant nutrients, such as calcium, force early flowering in cool weather crops, and increase potential for plant roots pathogens like Pythium spp. For this reason, it is important to prevent wide swings in daily temperature. Shading or covering water surfaces, insulating fish tanks and plant beds, and utilizing passive or solar heating in greenhouses are strategies many producers employ. In temperate areas where temperature changes drastically from season to season, producers can alternate fish and plant crops seasonally to reduce heating or cooling costs.

6.3 pH

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The pH is a measure of the acidity or basicity of a solution. It is determined by the presence or absence of free hydrogen ions (H^+^), where the more H^+^ present, the more acidic a solution is. An acidic solution has a low pH. The pH is measured on a scale from 1-14, with 7 being neutral. A pH value below 7 indicates a solution is acidic and above 7 indicates a solution is basic. The pH is recorded on a logarithmic scale and thus is not intuitive for many practitioners. For example, if the pH of an aquaponic system measures 7, then after two weeks measures 5, the pH has not dropped by a degree of 2, but rather 100 times. Understanding the pH scale is critical for water management and correction.

6.4 Total Ammonia-Nitrogen

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Nitrogen enters the aquaponic system as crude protein in the fish feed. Approximately 30% of protein in the fish food is retained by the fish. Seventy percent is digested and released as solid waste or excreted as ammonia via the gills or as urea (Timmons and Ebeling 2013). Total ammonia nitrogen (TAN) is comprised of two forms that exist in a ratio of un-ionized ammonia (NH3, which is toxic to fish) to ionized ammonia (NH4+ which in non-toxic). The presence of one form over the other is dependent on pH and temperature. At high pH (basic) and temperature, there is a higher proportion of toxic ammonia. At low pH (acidic) and temperature, ammonia binds to excess H^+^ ions and becomes the less toxic form, ammonium. Generally, water quality tests will give the TAN value, which encompasses both NH3 and NH4+. The exact value of toxic ammonia can be determined by taking the number that intersects the recorded temperature and pH (Table 7) and multiplying it by the present TAN value (Masser et al. 1999).

6.5 Alkalinity

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Alkalinity is an often-overlooked aspect of water quality but is essential in maintaining a stable system. Alkalinity is a measure of water’s ability to buffer, or resist, changes in pH (Wurts and Durborow 1992). The most common forms of alkalinity are carbonates (CO3-) and bicarbonates (HCO3-). These carbonates bind to free H^+^ ions, a result of nitrification, preventing a drop in pH. Water with low alkalinity and a steady rate of nitrification experience wide swings in pH, which can be detrimental to the health of fish, plants, and bacteria. It is recommended to maintain alkalinity between 60-140 mg/L.

6.6 Cycling the System

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Cycling refers to the process of establishing the biological filter. This can take between six to eight weeks (Figure 17). Nitrifying bacteria are found naturally in the environment, so the process begins by adding a source of ammonia.

This can be accomplished through adding fish, fish food, or water from a well-established system, or a combination of these. One of the most common mistakes when using fish to cycle a system is adding too many fish initially. This causes ammonia levels to spike, often resulting in fish death. Starting with 20% of the total fish capacity is a good rule of thumb. This allows the appropriate, system-specific biological organisms to colonize. If using a fish-less cycling strategy, household ammonia can be used. It is important to source surfactant-free ammonia, as it lacks detergents commonly added to these products that are unsuitable for the system.

6.7 Corrective Measures

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Low dissolved oxygen (below 5 mg/L): increase aeration, reduce feeding until corrected
Low pH (below 6.0): add base (calcium hydroxide, calcium carbonate, potassium hydroxide or potassium carbonate), reduce feeding until corrected
High ammonia (above 1 mg/L TAN): reduce feeding until corrected, perform 20% water exchange, check for accumulated solids, increase biological filtration
High nitrite (above 0.5 mg/L): reduce feeding until corrected, perform 20% water exchange, increase biological filtration
Consistently high nitrate: reduce fish biomass or feeding rate, add more plant biomass

7.1 Providing and Measuring Plant Nutrients

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Nutrients enter the aquaponic system in the fish feed. The amount of nitrogen that is available to the plant is directly related to the protein content of the feed. The higher the protein content, the more nitrogen is available for plant growth. Unfortunately, high protein feeds are very expensive, so feeding a higher protein feed than your culture species requires is cost prohibitive. Nitrogen comes from the breakdown of proteins, whose structural components are made up of nitrogen-rich amino acids. Approximately 20% of the nitrogen and 50% of the phosphorous from the feed is utilized by the fish for growth. Much of the N and P (70% and 30%, respectively) is excreted as a waste product by the gills, and the remainder (10% and 20% for N and P, respectively) is excreted as particulate waste. Particulate waste, what we refer to in aquaponics as “solid,” also contains macro- and micro-nutrients not absorbed by the fish. Utilizing this waste product can be accomplished through mineralization.

7.2 Common Nutrient Deficiencies

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A skill that is beneficial for aquaponics producers to keep in their toolbox is the ability to visually diagnose nutrient deficiencies. Once a plant exhibits symptom of a deficiency, severe stress is already occurring. Early detection and diagnosis are important.

Process of elimination can help growers successfully identify a nutrient deficiency. Key factors include recognizing where it occurs in the plant (mobile or immobile nutrient); taking note of the general appearance, such as color pattern or overall appearance; and eliminating other factors that may be causing the issue, such as light or heat damage. Below are common nutrient deficiencies that occur in aquaponics.

8.1 Physical Controls

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Preventing insects from entering the greenhouse is the best pest management strategy for aquaponics. Prevention is accomplished through consistent monitoring and physical controls. The use of adhesive, pheromone, or light traps can be used to monitor type of insect and level of infestation. Screens can be an effective physical control and can be used on outdoor systems or to cover vents in a greenhouse. Mesh size is an important consideration and should be as small as possible without restricting air flow and ventilation. Screen size for common pests are 0.15 mm for thrips, 0.73mm for white flies and aphids, and 0.8 mm for leaf miners. The most effective monitoring tool however, is the “farmer’s shadow” (close monitoring by operators). Physical controls can also include a sanitation area for workers and production of plant seedlings in-house.

8.2 Biological/Chemical Controls

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IPM strategies can also incorporate biological and/or microbial controls. These controls have many ecological advantages, including their host specificity, environmental beneficence, ability to be used in conjunction with chemical application, and that they are nontoxic and nonpathogenic to wildlife, humans, and other organisms not closely related to the target pest. Considering that these are precise, targeted control measures, cost can often be substantial.

Biological controls utilize insect predators of the target pest to control population numbers. While effective, use of beneficial insects may be cost prohibitive for smaller or hobby aquaponic systems. This strategy requires a tight predatory-prey ratio, as prey can be quickly depleted, leaving the beneficial insects with no food source. Predatory bugs such as spiders, ladybugs, praying mantis, bumblebees, and parasitic wasps are effective in combating pests.

8.3 Chemical Applications

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Pesticides derived from biological or microbial sources are also effective and widely available. Biopesticides are derived from natural materials such as animals, plants, bacterial, and certain minerals. Common biopesticides include biofungicides (Trichoderma), bioherbicides (Phytopthora), and bioinsecticides (Bacillus thuringiensis, B. sphaericus). B. thuringiensis (Bt) has become an increasingly common mechanism to target specific vegetable pests. Bt consists of a spore that contains a toxic protein crystal.

Certain insects that consume the bacteria release toxic crystals into their gut, blocking the system, which protects the pest’s stomach from its own digestive juices. The stomach is penetrated, causing insect death by poisoning from stomach content and spores themselves. This same mechanism is what makes Bt harmless to birds, fish and mammals, whose acidic gut conditions negate the bacteria’s effect.

8.4 Common Pests

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Mites: Mites are a very common pest, affecting hundreds of plants. These small arthropods are very small, often measuring less than 1 mm in length, and have sucking mouthparts. Damage to plants by mites includes brown stippling on leaves, upturned leaf margins, stunted plant growth, and webbing between plant structures (spider mites). Symptoms can mimic those of viral infections, particularly those caused by the broad mite, so identification should be done under a microscope. Mites typically have a 10-to-14 day life cycle and thrive in dark, humid conditions. Treatment options include neem oil and predatory insects such as ladybird beetles, lacewings, pirate bugs, predatory thrips, mites, and big-eyed bugs. Common types include Spider mite, Broad mite, Russet mite, and Cyclamen mites.

8.5 Disease Problems and Management

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Fish Disease and Treatment

Fish culture is inherently a messy business. Bacterial pathogens and parasites that affect fish are naturally occurring and opportunistic by nature. Good management, proper husbandry practices, and daily observation of fish can prevent many issues associated with fish health. Proper management techniques in the fish production of the aquaponics system should include: system design, water quality monitoring and correction, equipment maintenance, feed storage, fish observation to remove sick or dead fish, and worker sanitation. Common external physical signs of fish disease include:

8.6 Common Fish Diseases and Their Treatment

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Parasites

Ich (white spot disease): Ich is caused by the parasite Ichthyophthirius multifiliis (Ich). Ich appears on infected fish as small white specks on their skin and/or gills (Figure 21a). Fish may exhibit “flashing” behavior, characterized by a quick rubbing or scratching movements against the tank bottom, wall, or surface of the water (Durborow et al. 2000). Excess mucus is commonly present; however, the only clear sign may be a dead or dying fish. Treatment for Ich is difficult; however, elevating water temperature to above 85°F can kill Ich by disrupting its life cycle. Chemical treatments for quarantine tanks or decoupled systems include multiple treatments of formalin, copper sulfate (CuSO4), or potassium permanganate (KMnO4). Check appropriate dose rates before administering. These chemicals should not come into contact with plant components and must be administered in an isolated tank. Simply harvesting the fish may be the simplest solution.

8.7 Plant Disease and Prevention

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Plant disease problems can be difficult and time consuming to treat. Preventing issues from arising is the first step in proper plant care. Many foliar plant diseases are present during conditions of high temperature and humidity. Providing proper ventilation and reducing humidity will prevent conditions that allow mold and disease to spread to other plants.

Plant nutrition plays a direct role in disease resistance in plants (Agrios 2005). Providing the correct balance of nutrients is important not only for growth but also to decrease susceptibility and increase recovery from certain plant disease. Table 10 describes the role of certain nutrients for prevention of plant disease. Below are common plant diseases in aquaponic systems.

8.8 Steps to Prevent Plant Disease in Aquaponic Systems:

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Control temperature and humidity of the growing environment. High temperature and humidity often are the ideal environment for growth and spread of fungal and bacterial disease in plants. Particularly in a greenhouse or indoor facility, forced air ventilation and prevention of evaporation will reduce these parameters. It is also important to control these in and around the plant structure. This is accomplished through appropriate plant spacing and pruning fruiting crops with dense foliage.

8.9 Food Safety and Sanitation

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Sanitation and cleanliness of an operation is critical to ensure Good Agricultural Practices (GAP) regarding food safety (Hollyer et al. 2012). This is important because as of 2018, the CDC estimated that each year, 48 million people get sick from a foodborne illness, 128,000 are hospitalized, and about 3,000 people die. If the aquaponics industry wants to become a larger part of global food production and the fresh-cut sector, it is critical to maintain a good reputation and positive public perception of food safety for both fish and plants cultured within the same system.

9.1 Types of Greenhouses

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Free-standing greenhouses come in a variety of shapes and sizes (Figure 24). Choice of greenhouse depends on snow load and wind speed of a particular location. Free-standing greenhouses are less expensive than larger structures and are easier to optimize environmental parameters for different crop species. If multiple stand-alone structures are used, increased sanitation protocols are required to prevent insect pest and disease issues from being transferred between structures by workers.

9.2 Greenhouse Covering Options

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Greenhouse coverings come in a variety of materials, including glass, rigid plastic (fiberglass, polycarbonate, or acrylic), and plastic films. The appropriate choice depends on your climate zone and budget. Regions with a colder climate will require the covering to provide increased insulation and low heat transfer measured by the R-value and U-value, respectively. The R-value measures how well the material insulates. The higher the R-value, the more insulation the material provides. The U-value quantifies heat transfer and describes how much heat is lost or gained. Materials with a lower U-value will be more energy efficient. Approximately 75% of plastic used for covering greenhouses in the U.S. is air-inflated double- layer polyethylene plastic. 6ml polyethylene plastic covering is inexpensive and has an R-value of 1.4 and a U-value of 0.5 (high insulation capacity and energy efficient). A single layer fiberglass covering is moderately expensive and has an R-value of 0.83 and a U-value of 1.2 (moderate insulation capacity and not energy efficient) (Table 11). Choosing the right material for your climate zone is critical to reduce heating costs during winter. Energy cost is the second greatest production expense, just behind labor.

9.3 Heating and Cooling Options

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Heating: For small or backyard-size producers, implementing a passive heating system can help reduce heating costs during cold months. In this type of system, sunlight enters the south wall. The north wall has reflective material to trap and store heat. Black barrels filled with water absorb heat from sunlight during the day and slowly release the heat during the night. Thermal curtains can be hung on the south wall to trap heat during the night (Figure 26). While helpful to reduce heating costs, this practice would not be practical for large producers as it takes up valuable production space in the facility and is not able to maintain a consistent and reliable temperature.

9.4 Indoor Production

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Moving production into an insulated building is suitable for producers who want to be close to urban markets, have a lack of arable land, or live in a climate not suitable for outdoor or greenhouse production.

No matter where a plant is grown, it still requires optimal conditions to reach its maximum yield potential. In addition to the controls discussed above, producers must also provide light suitable for optimal plant growth. For plants, light stimulates seed germination, food production, flowering, chlorophyll manufacturing, and branch and leaf thickening.

The Big Picture

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The world population is an estimated 7.7 billion and is expected to reach 10 billion by 2050. To feed this expanding global populace, food production must increase by 30-50%. This increase would require that land used to raise crops expand by almost 1.5 billion acres; that is about ¾ the size of the continental United States.

In 2020, agriculture utilized almost 50% of the world’s vegetated land. The ongoing increase in atmospheric CO2 levels, leading to increased global warming, would be exacerbated by the large-scale conversion of forested lands to crop land necessary for food production. In addition, current agriculture production accounts for 90% of all water used by humankind. This growth and consumption of resources is not sustainable. Alternative ways to increase food production are required; we simply cannot just do more of what we are doing now.

Dr. Rachel Fogle on using Aquaponics at one of the top STEM Universities

Mon, 29 Mar 2021 10:16:00 +0000

Dr. Rachel Fogle is an Associate Professor of Biological Sciences at Harrisburg University of Science and Technology. She is also the lead and coordinator of the Aquaponics Initiatives.

We sit down in and talk about the Harrisburg University’s aquaponic initiative and how Aquaponics is a great fit for STEM education. If you are an educator, you’ll love her advice and tips in how to educate and instill wonder in the next generation. We also jump in on challenges and what excites her in biological science and aquaponics, enjoy!

2021 Indoor Ag Tech Landscape

Thu, 25 Mar 2021 00:00:00 +0000

FarmHub is thrilled to be listed on the Indoor AgTech Landscape for 2021!

Michael Rose and Chris Taylor of The Mixing Bowl and Better Food Venturesprovide a snapshot of agriculture technology impacting food security and impact in Controlled Agriculture Environments (CEA).

You can read all about the landscape in agtech on AgFunder: https://buff.ly/311haDb.

Nicholas Metropulos on being new to Aquaponics, fighting food security, and operating a non-profit

Mon, 22 Mar 2021 10:43:00 +0000

Nicholas Metropulos is the Executive Director of Marine Education Initiative, a nonprofit organization based in Boca Raton, FL. Their mission is to educate and empower youth to safeguard marine ecosystems for the future.

They recently saw the opportunity to add an Aquaponic system to their nonprofit as part of their food security goals for South Florida. Hear how they are now able to donate 10 times the amount of food than their previous initiative and how they are working to provide sustainable, high-quality meals to those that need it the most. Fun to hear from someone who after research, seeing the opportunity and despite the challenges jumped in to Aquaponics for impact.

Kevin Fitzsimmons, Ph.D on Aquaponics, Aquaculture and Global Developments

Mon, 15 Mar 2021 10:44:00 +0000

Kevin M. Fitzsimmons, Ph.D. the director of International Initiatives and a Professor in the Department of Environmental Science at the University of Arizona. He is the Past-President of the World Aquaculture Society.

We sit down with him in Myanmar where he is the team leader for the Myanmar Sustainable Aquaculture Program. We discuss his start in Aquaponics 40 years ago!, integrated farming systems, inspiring projects in Aquaculture and Aquaponics with nextgen farmers.

Aquaponic farm growth and success, regenerative agriculture, and fish fermenting with Joe Pate!

Mon, 08 Mar 2021 10:45:00 +0000

Joe Pate is the owner and CEO of Regen Aquaculture. He has designed and built aquaponic systems, is an advisor for the Aquaponics Association, and a flat out epic researcher. He’s passionate about the science and impact of innovation within the Aquaculture and Aquaponic agriculture.

Joe love’s working with farmers to improve their operations, help their success and innovate with regenerative methods. We soak up every word from his perspective and experience, enjoy!

Announcing new video series ‘People of Aquaponics’ connecting with the movers and shakers of the Aquaponic and Aquaculture industry.

Sat, 06 Mar 2021 00:00:00 +0000

We are a social-impact aquaponic technology company powering the heroes of next-gen aquaponic food production. Our recently released video series, People of Aquaponics, aims to validate the rapidly growing aquaponic community by connecting with awesome people, doing amazing things globally with aquaponics and aquaculture.

“I’m personally inspired by the aquaponic community. You are a unique group of people with an underlying vibe for social impact and caring for people and the planet. Of course, aquaponics is an impactful avenue, but the people behind all of this, that’s who I’m excited to connect with and share with the community through this series “said Daniel Robards, cofounder and CBDO.

Mathilde Eck and Microorganisms and bacterial communities in Aquaponics

Mon, 01 Mar 2021 10:51:00 +0000

Mathilde Eck is a PHD candidate and researcher at the Gembloux Agro-Bio Tech - University of Liège in Belgium. Gembloux Agro-Bio Tech, an internationally renown campus where forefront of sustainable development and eco-innovation.

Working in the Integrated and Urban Plant Pathology Laboratory and Centre de Recherches en Agriculture Urbaine (Urban Agriculture Research Center) she has devoted years in researching and exploring microorganisms and more specifically bacterial communities in Aquaponic Systems.

Matthew Braud of Sustainable Harvesters on running a commercial Aquaponics farm & future impact

Thu, 25 Feb 2021 10:52:00 +0000

Matthew Braud is the founder and co-owner of Sustainable Harvesters, based out of Houston, Texas. Sustainable Harvesters is an environmentally controlled commercial Aquaponic greenhouse producing 7000 heads of lettuce a week in their 12,000 square foot grow space.

We sit down and talk about the life of a commercial aquaponic farmer and the future of aquaponics. You’ll hearing from his experience and practical advice from a next gen farmer.

Learn more

Sustainable Next-gen Farming, Research and Aquaponics with Dr. Ryan Lefers

Wed, 17 Feb 2021 10:54:00 +0000

Dr. Ryan Lefers is an agricultural engineer, research scientist at the King Abdullah University of Science and Technology (KAUST) and the CEO of Saudi Arabia based Red Sea Farms.

Raised on a farm in South Dakota, Dr. Lefers quickly became passionate about the nexus in sustainable agriculture systems of using two of the world’s most abundant natural resources: salt water and sunlight. At KAUST and Red Sea Farms, his team has developed groundbreaking technology for salt tolerant agriculture and salt water cooling technologies connected to Controlled Environment Agriculture (CEA). This includes using seawater to use grow salt-tolerant crops, such as newly identified varieties of tomatoes and green vegetables.

Marena Toth and Aquaponics for Students with Disabilities

Wed, 17 Feb 2021 10:49:00 +0000

Marena Toth is the Program Coordinator at Growing Together Aquaponics. The mission of Growing Together Aquaponics is to provide individuals with disabilities with job-training skills leading to competitive, integrated employment.

With a background in Adaptive Physical Therapy, Marena found students with disabilities can thrive in an aquaponics program and can be an ideal environment for a vocational training program for students with intellectual or developmental disabilities.

https://northcountrybrewing.com/growing-together-aquaponics/ https://www.facebook.com/growingtogetheraquaponics https://www.instagram.com/growingtogetheraqua/

#aquaponics #socialimpact #agtech

Dr. Paul Brown on the Future of Aquaponics, Aquaculture, and Fish Feed

Wed, 17 Feb 2021 10:47:00 +0000

Professor Brown conducts research in aquaculture, aquaculture nutrition and aquaponics. He teaches Aquaculture, Fish Physiology, Aquaponics and a component of the Fisheries Field Practicum. He has defined diets for new and emerging aquaculture species for the US aquaculture industries and has documented the ability to raise multiple species in north central Indiana. He is expanding his research to international applications, currently in Guatemala and Zambia. His approach is development of sustainable aquaculture diets using existing agricultural products and production systems demanding less water than traditional approaches. Additional considerations are integrated systems in remote areas that link food production systems to documented human nutritional needs and water conservation/sanitation.

Releasing Sparky into the Wild Data World!

Tue, 05 Jan 2021 00:00:00 +0000

You are all familiar with JD and Tawnya Sawyer at the Aquaponic Source. They just released their online trainings and have began moving their years of experience to the cloud. They also have tons of ready-made systems for residential and school settings that can be powered by FarmHub.

In addition to their courses being available online, FarmHub and The Aquaponic Source have teamed up to deliver a powerful all-in-one solution for tracking your data. This enables you to:We’ve been hard at work trying to simplify your data log collection processes. We’re proud to announce that we’re releasing our public beta version of Sparky CLI!

2020 Recap: The impossibilities becoming possible

Tue, 22 Dec 2020 00:00:00 +0000

FarmHub, a social-impact aquaponic technology company has a cloud based data management and visualization solution for the Aquaponic grower. Designed to improve the way aquaponics growers grow, FarmHub provides an efficient, time saving, user friendly software for the rapidly increasing number of aquaponics growers worldwide.

“We have promised to provide data-driven solutions to our growers’ pain points and are continually innovating our software in exchange for their membership and contribution to doing awesome things with Aquaponics for people and the planet,” said Daniel Robards, cofounder and CBDO.

Common Practices for Harvesting Fish Around the Globe

Sun, 29 Nov 2020 00:00:00 +0000

Harvesting fish is one of the most important aspects of a high-quality aquaculture distribution chain. Whether you’re eating fish from a home aquaponics system or a large commercial aquaculture system, knowing these methods will be very helpful.

Your harvesting method could also influence the quality of fish, therefore, good practices must be strictly observed in harvesting aquaculture products to maintain their marketability and secure safety for human consumption. Although different methods of harvesting are practiced in different regions of the world, there are still common practices that the aquaculture sectors are doing and some of those are listed below:

Joining Forces with The Aquaponic Source to Further Aquaponics Globally

Mon, 23 Nov 2020 00:00:00 +0000

In addition to their courses being available online, FarmHub and The Aquaponic Source have teamed up to deliver a powerful all-in-one solution for tracking your data. This enables you to:

Releasing fresh features to power the heroes of next-gen aquaponic food production.

Tue, 03 Nov 2020 00:00:00 +0000

“We have promised to provide data-driven solutions to our growers’ pain points and are continually innovating our software in exchange for their membership and contribution to doing awesome things with Aquaponics for people and the planet,” said Daniel Robards, cofounder and CBDO.

Martin Niwinski - An Aquaponic superhero at ECOLIFE

Fri, 18 Sep 2020 00:00:00 +0000

Martin Niwinski has a sharp eye to see problems in an aquaponic system before they become too serious. A superpower developed over time.

Teaching others how to grow nutrient dense food in a sustainable manner seems to be an integral part of your work and vision. Tell me more why these are so close to all you are doing?

Aquaponics is part of the solution to fixing our destructive food system. So much of our natural resources are destroyed or tied up in food production that using them more wisely is essential. People are really disconnected from growing their own food and teaching them to grow their own is very empowering.

The Common Causes of Fish Death in Aquaculture

Sat, 05 Sep 2020 00:00:00 +0000

In aquaculture, good production is attained by maintaining good growth, high survival rate and good fish condition and appearance. This could be achieved with good aquaculture practices, good feeding regime and maintaining healthy stocks. The water in which the fish lives contributes significantly to the overall health and well-being of the fish. Furthermore, presence of pathogens including fungus, bacteria, virus and parasites could bring harm to fish stocks and disturb the system. Regular monitoring of water quality and daily assessment of fish condition could help fish growers prevent further imbalance in the system or possible infection if there is, which could lead to disease and even death and massive fish kills. Although prevention is always better than cure, fish farmers also must be knowledgeable about the specific treatment to a specific fish disease just in case.

A-frame systems

Thu, 03 Sep 2020 00:00:00 +0000

A-frame systems consist of a stepped arrangement of hydroponic channels (Sánchez-Del-Castillo et al. 2014), or angled panels of geotextile for aeroponic cultivation (Hayden 2006). Fruit bearing crops growing in the lower sections of an A-frame system may experience partial shading, and consequently produce a high number of small and malformed fruit, experience increased fruit rot, and exhibit problems with fruit colouration. This can be avoided by using systems with grow beds that slowly rotate around the A-frame to ensure that the plants obtain uniform sunlight, irrigation and nutrients as they pass through different points in the structure. For example, the A-Go-Gro (AGG) system developed by Sky Greens in Singapore (Figure 14) consists of tall aluminium and steel A-frames that can be as high as 9 metres tall, with 38 tiers of growing troughs that can contain either soil or hydroponic solution. Each frame has a footprint of only 5.6 m², and the system is capable of producing 1000 tons of vegetables per hectare/year. The frames are housed in translucent greenhouses and the rotation of the troughs at a rate of 1 mm/s means that each trough rotates around the frame three times a day, which ensures uniform distribution of sunlight and good air flow, and reduces or even eliminates the need for artificial lighting in some areas of the greenhouse. Rotation is powered by a patented low carbon hydraulic system that makes efficient use of gravity and therefore consumes little energy; only 60 W is required to power one frame. Rainwater collected in an overhead reservoir passes down through the water pulley system, and is then redirected back up to the reservoir by a pump powered by a generator (Al-Kodmany 2018).

Aquaponics and social enterprise

Thu, 03 Sep 2020 00:00:00 +0000

Social enterprises, as distinct from traditional private or corporate enterprise, aim to deliver products and services that cater to basic human needs. For a social enterprise, the primary motivation is not maximising profit but building social capital; economic growth is therefore only part of a much broader mandate that includes social services such as rehabilitation, education and training, as well as environmental protection. There is growing interest in aquaponics among social enterprises, because it represents an effective tool to help them deliver their mandate. For example, aquaponics can integrate livelihood strategies to secure food and small incomes for landless and poor households. Domestic production of food, access to markets, and the acquisition of skills are invaluable tools for securing the empowerment and emancipation of women in developing countries, and aquaponics can provide the foundation for fair and sustainable socio-economic growth.

Aquaponics and wellbeing

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Aquaponics offers an innovative form of therapeutic horticulture, a nature-based approach that can promote wellbeing for people with mental health problems through using a range of green activities such as gardening and contact with animals. Over the past decade, a number of social enterprises have emerged that provide therapeutic horticulture programmes for improving the wellbeing of local communities. The social enterprise approach builds on ‘Social Firms’ by facilitating people with mental health problems to develop new skills and re-engage with the workplace. A Social Firm is a specific type of social enterprise where the social mission is to create employment, work experience, training and volunteering opportunities, within a supportive and inclusive environment, for people who face significant barriers to employment, and in particular for people with a disability (including mental ill health and learning disability), abuse issues, a prison record, or homeless issues (Howarth et al. 2016).

Aquaponics as an educational tool

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Aquaponics promotes scientific literacy and provides a useful tool for teaching the natural sciences at all levels, from primary through to tertiary education. An aquaponics classroom model system provides multiple ways of enriching classes in Science, Technology, Engineering and Mathematics (STEM). The day-to-day maintenance of an aquaponics system also enables experiential learning, which is the process of learning through physical experience, and more precisely the ‘meaning- making’ process of an individual’s direct experience. Aquaponics can thus become an enjoyable and effective way for learners to study STEM content. It can also be used for teaching subjects such as business and economics, and for addressing issues like sustainable development, environmental science, agriculture, food systems and health.

Automatic feeders

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The automation of feeding requires knowledge about the feeding habits of the species in question. We also need to know technical details, such as the number of fish in each tank and their sizes. Manual feeding has advantages, as mentioned above, and is still used to ‘keep in touch’ with the fish. Nonetheless, technological developments can facilitate this labour. Nowadays there are many types of automatic feeders, especially for large-scale projects with a large biomass. Here we focus on the different types of automatic feeders used in RAS.

Biological pest control

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The terms ‘biological control’ and its abbreviated synonym ‘biocontrol’ have been used in different fields of biology, most notably entomology and plant pathology. In entomology, it has been used to describe the use of live predatory insects, entomopathogenic nematodes, or microbial pathogens to suppress populations of different insect pests. In plant pathology, the term applies to the use of microbial antagonists to suppress diseases as well as the use of host-specific pathogens to control weed populations. In both fields, the organism that suppresses the pest or pathogen is referred to as the biological control agent (BCA).

Classification of aquaponics

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The delineation between aquaponics and other integrated technologies is sometimes unclear. Palm et al. (2018) proposed a new definition of aquaponics, where the majority (> 50%) of nutrients sustaining plant growth must be derived from waste originating from feeding the aquatic organisms.

Aquaponics in the narrower sense (aquaponics sensu stricto) is only applied to systems with hydroponics and without the use of soil. Some of the new integrated aquaculture systems which combine fish with algae production would also fall under this concept. On the other hand, the term aquaponics in the wider sense (aquaponics sensu lato) can be applied to systems which include horticulture and crop production techniques which utilize the mineralization processes, buffer and nutrient storage function of the different substrates, including soil. Palm et al. (2018) propose the term ‘aquaponic farming’ for these activities.

Conclusions

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While vertical aquaponic systems may increase the number of plants that can be grown per unit of surface area compared with horizontal systems, it is important that they also result in increased yields. From a commercial point of view, the effects of gradients within some types of vertical system on crop value will depend on how the crop is going to be processed and marketed. For example, if lettuce is grown to be sold as individual heads, then the non-uniform productivity of growing towers, living walls and static A-frame systems would be a potential weakness compared with conventional horizontal aquaponic systems or vertical stacked bed systems. However, if the crop is destined for pre-cut salad bags, then crop uniformity may be irrelevant, and the increased yield per unit area could be a significant advantage. Besides affecting crop yield and quality, harvest efficiency in vertical and multi-tier horizontal systems may also be adversely affected since it will require working at different heights. The costs of the different types of vertical growing system also vary widely, depending on their complexity and the degree of automation. Therefore, crop utilization and marketability, and an investigation of the cost‐to‐benefits ratio of these growing systems, will be the ultimate criteria to decide whether vertical aquaponics can provide a viable alternative to conventional horizontal systems.

Connections, water movement and aeration

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Plumbing

PVC pipes are most commonly used for plumbing. They are available in many standard sizes, are cost-effective, easy to cut and adapt to a wide range of adapters and connectors, and also usually last a long time. Other materials could also be used, but they must be safe for both the fish and the plants, and for food production. Some general advice about pipes:

pipes have to be ‘just right’ – if the pipes are too small there will be a problem with leaks, and if they are too big the solids will not get flushed out because the water pressure will be too low

Crop scheduling

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Planting all the crops on a farm at the same time results in production waves instead of continuous production. Continuous production is what farmers need in order to satisfy weekly or even bi-weekly demand, by always having mature crops in the farm. A planting and harvesting schedule that accounts for the life cycles of each crop is a useful tool to achieve this (Storey 2016c):

Leafy greens like chard, lettuce, and cabbage have a 4-6 week cycle from transplant to harvest

Current research themes in aquaponics

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Trends in technology

As we saw above, the design of successful aquaponic systems depends on the user group. High-yield, soil-less production requires a high input of technology (pumps, aerators, loggers) and knowledge, and is therefore mostly suited for commercial operations. However, it is entirely possible to design and operate low-tech aquaponic systems that require less skill to operate, and still yield respectable results. This implied trade-off (high-tech/low-tech) and the broad range of applications of aquaponics have consequences for further development pathways for the technology, system design, and socio-economic aspects. Aquaponic technology might develop in at least two directions: on the one hand towards low-tech solutions (probably mostly in developing countries and for non- professional applications) and, on the other hand, towards highly efficient hi-tech installations (predominantly in developed countries and with professional/commercial partners) (Junge et al. 2017).

Designing feeds for aquaponics

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Fish feeds for aquaponics can be home-made or bought from specialized feed companies that formulate specific diets depending on the species and age of the fish. Normally commercial producers use specialized feeds since they are guaranteed to meet all the nutritional needs of the fish, and tend to be more cost effective compared to making and formulating one’s own feed. However, formulated feeds are not always perfect and may have varying effects on the quality of the water where fish live and excrete waste. Only recently have scientists and engineers begun to look at specific diets for fish in recirculation systems and in aquaponic units. Theoretically it seems possible to provide fish with pelleted feed, which will help them to grow quickly, while providing enough nutrients for the plants that will later ‘feed’ on this water. In practice, however, things are more difficult, and depend on many complex parameters such as the temperature and pH of the recycled water, as well as microbiota in fish intestines and in biofilters. An aquaponics practitioner should know the basics of feed composition in order to have some way to judge which feed would be best to start off with. Although it may not be necessary to design feeds from scratch, students should be able to choose the best feed for this system after reading the following sections.

Elements of aquaponic systems

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The ‘hardware’ of an aquaponic system consists of (i) the fish tank, (ii) the water and air pumps, (iii) the solids removal units (drum filters, settlers), (iv) the biofilter, (v) the plant grow beds, and (vi) the plumbing materials. These elements are populated by a community, where the primary producers (plants) are separated from consumers (mostly fishes), and ubiquitous microorganisms build a ‘bridge’ between the two main groups.

Figure 2: Main components of an aquaponic system (redrawn after Rakocy et al. 2006)

Energy requirements

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As with all living animals, fish require energy, and that energy is provided by the oxidation of the organic components in feed. Fish require energy to carry out their daily activities, such as breathing and swimming, and to transform, restore, and grow their body tissues. The energy requirements of fish depend on their physiological state and on the environmental conditions. In general fish make a more efficient use of the energy ingested compared to terrestrial mammals, due to the following reasons:

Examples of aquaponic systems around the world

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A wide range of aquaponic systems exist in all continents. Table 6 summarizes several systems and their main characteristics.

Europe

Between the years of 2014-2018, the European Union funded COST Action FA1305 ‘EU Aquaponics Hub’, which involved the cooperation of member countries in the research of aquaponic systems as a pertinent technology for the sustainable production of fish and vegetables in the EU. The website of the action is a very good source of information, with links to fact sheets, publications, and training school videos. The same group performed a survey of the use of aquaponics in Europe, underlining that most units are small and related to research (Villarroel et al. 2016). A map of nearly all known aquaponics facilities in Europe was published in Google Maps.

Feasibility study: location and infrastructure considerations

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Table 2 outlines the most important location and infrastructure considerations when designing a new aquaponic system.

Site stability and foundations

Water is heavy. Choose stable and level ground for building your aquaponic system. If the ground is not stable, the foundations will be unstable and leaks could occur because of movement of the pipes.

Climatic conditions at the location

Consider how to protect the aquaponic system from extreme weather events. Europe is located in a moderate climatic zone characterized by changing seasons with different temperatures and day lengths. Therefore you should consider what to do during periods of low temperature and short daylight. One option is to stop production and start again in the spring; the other is to heat the water and air and provide artificial lighting. On the other hand, extremely high temperatures have to be avoided during summer. You can install shading nets, or paint the outside of the greenhouse with white paint. Good quality greenhouses have automated sprinklers and ventilation devices. Remember that systems with a large water volume are more resistant to overheating than those with a small water volume. Having access to additional water (spring water etc.) for cooling using a heat exchanger can also help. In addition to solar radiation, the fish and electrical components also produce a lot of thermal energy that has to be removed during warm weather.

Feeding strategies

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Apart from using adequate feeds, we need to ensure that the pellets provided are the right size for the mouth of the fish. For small fish this usually means a fine powder and for larger fish a round pellet that can be several mm in diameter. For example, Aquaponics USA suggests using powder for tilapia from hatching to 3 weeks old, and then a fingerling crumble (1/32 inch or 0.9 mm) until they grow to about 2 cm in length, fingerling pellet (1/16 inch or 1.6 mm) until about 4 cm in length, and grow out pellet (3/16 inch or 4.8 mm) after about 6 cm in length.

Fertigation

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Fertigation is the use of fertilizers in the appropriate combination, concentration and pH. Mineral nutrition is critical for optimal plant growth. Optimal nutritional conditions can vary between different plant species, for the same plant species at different times of its life cycle, for the same plant species at different times of the year, and for the same plant species under different environmental conditions. Even balanced aquaponic systems can experience nutrient deficiencies. Fish feeds do not necessarily have the right quantities of nutrients for plants, and generally have low iron, calcium and potassium values (see Chapter 5). Thus supplementary plant fertilizers may be necessary, particularly when growing fruiting vegetables or those with high nutrient demands. Synthetic fertilizers are often too harsh for aquaponics and can upset the balanced ecosystem. In general, iron is added as chelated iron to reach concentrations of about 2 mg/litre. Calcium and potassium are added when buffering the water to the correct pH. These are added as calcium hydroxide or potassium hydroxide, or as calcium carbonate and potassium carbonate. The choice of the buffer depends on the plant type being cultivated: leafy vegetables may need more calcium, while fruiting plants may need more potassium (Somerville et al. 2014c).

Fish welfare

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Introduction

Aquaculture is one of the few types of animal farming that has grown continuously over recent decades, by about 10% annually on an international level (Moffitt & Cajas-Cano 2014). However, as production increases and new methods appear, such as aquaponics, we have been witness to more problems related with fish health and welfare. Although it may seem surprising, more than 1300 scientific articles have been published on fish welfare since 1990 (see Table 2). Not all those studies deal with commercially produced species, but in general the number for all fish is comparable to or higher than some other species like sheep, horses or poultry.

Food safety risks in aquaponics

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A major food safety concern with aquaponics is the cultivation of vegetable crops in water containing fish excreta and other organic matter, including fish and plant particulate residuals. Pathogenic bacteria can enter the system via water, animal faeces, plant seedlings, tools or humans. The major risk from warm-blooded animals is the introduction of Escherichia coli, while birds can carry Salmonella spp. (FAO 2014). E. coli O157:H7, Salmonella spp., and Listeria monocytogenes are the main foodborne pathogens that can be found in recirculating water system and which have been shown to survive in these conditions. Faecal contamination of aquaponic systems has mostly been detected when a poor quality water source was used or when faecal inputs from domestic animals or wildlife were possible (Fox et al. 2012). Despite previously published reports indicating internalization² of human foodborne pathogens such as E. coli O157:H7 and Salmonella in vegetables, the study done by Moriarty et al. (2018) did not provide evidence for bacterial internalization. Internalization may be a phenomenon only seen in specific circumstances such as very high bacterial concentration and plant injury (especially when roots are damaged) that increase the probability for the occurrence of bacterial internalization.

Fundamentals of scientific research methodology

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Research methodology is a discipline of scientific procedures. It includes theory, analysis and guidelines for how research should proceed: how research should be conducted and the principles, procedures, and practices that direct research. Research methodology is the specific set of procedures or techniques used to identify, select, process, and analyse information about a topic. Since methodology can differ between different disciplines, therefore there is an assortment of different research methodologies which may not be appropriate for all research problems (Nayak and Singh 2015). Methodology should not be confused with scientific methods, which mean ways or techniques for gathering information/results. Scientific methods describe the way in which scientific knowledge is gained. In a research paper, the materials and methods section allows the reader to critically evaluate a study’s overall validity and reliability, because it states how the data were collected or generated, and how they were analysed. The following is an example of a research methodology:

General cultivation practices

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Staggered planting allows for continual harvest and transplant of vegetables. It is best to have an excess of plants ready to go into the system, as waiting for seedlings to be ready for transplanting is a source of production delay. Crop scheduling is covered in more detail in Chapter 7.

Transplants from seeds

Collecting seeds from growing plants is an important cost-saving and sustainable strategy, except when F1 hybrid plants are being grown (see below). Seed should only be collected from mature plants, as young plant seeds will not germinate, and old plants will have already dispersed their seeds. Collecting seeds from a number of different plants will help to retain genetic diversity and healthy plants. There are two major categories of seeds: dry seed pods and wet seed pods. Dry seed pods include basil, lettuce and broccoli. Seeds from basil can be harvested throughout the growing season, while lettuce and broccoli can only be harvested after the plant is fully mature and no longer usable as a vegetable. The seed heads should be cut from the plant and stored in a large paper bag for 3–5 days in a cool, dark place, and then lightly shaken to release the seeds. After passing the contents of the bag through a sieve, the seeds should be placed in a paper bag for storage (Somerville et al. 2014a).

General external anatomy

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The main idea of this section is to introduce several important anatomical features of fish and to relate them to function and physiology. There are more than 20,000 species of freshwater and marine fish on our planet, each with specific requirements and ecological niches, which has led to specific body adaptations. However, many of the fish, especially teleosts (bony fish with a moveable pre-maxilla), share some common features. Although the number of species used in aquaculture is probably over 200, the number used in aquaponics is narrower, and mostly restricted to freshwater fish (Table 1).

General internal anatomy

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In this section we will outline the most important internal organs of fish (Figure 4), underlining the main differences with mammals and some important facts that influence how fish should be maintained.

Figure 4: General internal fish anatomy (source http://www.animalsworlds.com/internal-anatomy.html)

Brain

Fish have small brains compared to terrestrial vertebrates. For example, the human brain weighs approximately 1.4 kg and represents around 2% of the total body mass, but fish brains only represent 0.15% of their body mass. Nonetheless, unlike many vertebrates, fish brains are quite adaptive and maintain the ability to grow and change throughout life (they maintain the ability to produce new neurons; Zupanc 2009). Fish brains have three main regions: the forebrain (with the olfactory lobes and telencephalon), the mid-brain (optical lobes), and the hind-brain (cerebellum). Fish do not have a neocortex, which some scientists think is necessary to be fully conscious of pain, but other important structures exist that suggest they can feel pain, such as the amygdala, the cerebellum, and the pallium (outer layer of the telencephalon; for more information see Braithwaite 2010).

General introduction to fish feeding

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Feeding and fish nutrition are fundamental aspects of aquaculture, both in terms of fish growth and in economic terms. Proper feeding depends on the development of quality feeds and on choosing appropriate methods to distribute the feed to the fish in the tanks. Apart from affecting growth, feeding can also affect fish health and welfare, which depends in turn on how much we know about the requirements of each species. Each species has its own natural history and well defined stages of growth, which should be understood in order to provide optimal care.

Good agricultural and good hygiene practices

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In general, good practice means quality assurance activities which ensure that food products and food related processes are consistent and controlled and assure quality procedures in food systems (Raspor & Jevšnik 2008), or simply defined as Doing things well and guaranteeing it has been done so (FAO 2006). GAP is the selection of methods which can best achieve the objectives of agronomic and environmental sustainability in primary food production. GHP consists of practical procedures and processes that return the production or processing environment to its original condition (cleaning programme); ensure that buildings and equipment operate efficiently (maintenance programme); and control for cross-contamination (usually related to people, surfaces, and the segregation of raw and processed products) (Raspor & Jevšnik 2008). GAP and GHP should be adopted to reduce as far as possible any source of contamination (Figure 2).

Greenhouse control systems

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Control systems include those for lighting, heating, cooling, relative humidity, and carbon dioxide enrichment. Whilst it is helpful to have a fully controlled environment, aquaponic cultivation can also thrive without it, or with only some of the parameters being controlled.

Light

Maximum light transmission, of the appropriate quantity and quality (PAR, 400-700 nm), is crucial for optimal photosynthesis, growth and yield. If there is too much light in the summer, shade paint or white wash can be sprayed on the outside of the greenhouse. This will either wear off by the end of the growing season, or it can be washed off. External fabric shade cloths made of varying degrees of mesh size to exclude specific amounts of light (e.g. 30%, 40%, 50% shade) can be placed on the outside of the greenhouse or hung inside it. If there is too little light during the winter, white reflective ground covers can significantly increase light levels to the plant canopy (Rorabaugh 2015).

Growing towers

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Growing towers are vertical tubes through which nutrient-rich water is diffused from the top, usually through a drip emitter, thereby creating ‘rain’ inside the tower as it drips over the plant roots that are suspended in the air. The towers, or columns, may either be hollow or filled with a substrate that provides support for the roots and aids in water dispersal. In its simplest form, a growing tower may be a section of PVC pipe with holes cut into the sides. In their comparative study of lettuce grown in a hydroponic tower system and a conventional horizontal NFT system, Touliatos et al. 2016 found that the tower system produced 13.8 times more crop than the horizontal system, calculated as a ratio of yield to occupied floor area. However, the mean fresh weight of the lettuces grown in the horizontal system was significantly higher than that of the lettuces grown in the vertical system. While crop productivity was uniform in the horizontal system, shoot fresh weight decreased from the top to the base of the tower, most likely as a result of gradients in nutrient availability and light intensity. Similar light gradients have been reported in other greenhouse trials using hydroponic tower systems (Liu et al. 2004; Ramírez‐Gómez et al. 2012). Strawberries grown in vertical PVC towers filled with perlite at a plant density of 32 plants/m² produced a marketable yield of 11.8 kg/m²; however, yield per plant was reduced by 40 g with every 30-cm decrease down the height of the tower, as a result of suboptimal light conditions in the lower sections of the tower (Durner 1999). The diameter of the towers will also have an effect on plant growth. Water content values in tall and narrow towers will be lower than in shorter and wide towers having an equal volume of growing medium per unit length, and the roots of the plants will be subjected to larger daily temperature variations which may affect nutrient uptake and disturb the carbohydrate metabolism in the root, resulting in inhibited growth (Heller et al. 2015).

HACCP system

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Food safety management consisting of prerequisite programmes (GAP and GHP) and upgraded with a HACCP (Hazard analysis and critical control points) system is a roadmap for aquaponic producers for reducing the risks that may jeopardize product safety. A comprehensive HACCP plan describes procedures for all aspects of production and processing. It also provides a structure for assessing an operation, and serves as a reference for workers during training. Because a HACCP system always has to be adapted to each individual set-up, a generic approach is presented in Table 4.

History of aquaponics

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The concept of using fish excrement to fertilize plants has existed for millennia, with early civilizations in both Asia and South America using this method. The most well-known examples are the ‘stationary islands’ or Aztec chinampas set up in shallow lakes in central America (1150–1350 BC), and the rice-fish aquaculture system introduced in Asia about 1500 years ago, and still used today. Both the rice-fish aquaculture system and the chinampas were listed by the FAO as Globally Important Agricultural Heritage Systems (Koohafkan & Altieri 2018).

Hydroponic systems

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There are three main types of hydroponic systems (see also Module 1). In media bed hydroponics the plants grow in a substrate. In nutrient film technique (NFT) systems the plants grow with their roots in wide pipes supplied with a trickle of water. In deep water culture (DWC) or floating raft systems the plants are suspended above a tank of water using a floating raft. Each type has its advantages and disadvantages which are discussed in more detail below. The evidence is somewhat contradictory in terms of their relative efficiency for crop production in aquaponic systems. Lennard and Leonard (2006) compared the three hydroponic sub-systems for lettuce production and found the highest production in gravel media beds, followed by DWC and NFT. However, subsequent studies by Pantanella et al. 2012 found that NFT performed as well as DWC, while media bed consistently underperformed in terms of yield.

Important parameters in aquaponics

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In addition to monitoring the general physico-chemical parameters that are important for maintaining water quality in aquaponic systems, and the biological parameters that indicate the system’s performance and reveal potential problems with water quality, it is also necessary to carry out regular check ups on the performance of the technology (filters, water, air pumps, etc.).

Technology

Solids removal

OPERATING PROCEDURE: A major consideration in aquaponics is the retention time and the removal of large particulate matter. These particles include uneaten food, fish waste, as well as other sources of biological material, such as plant particles. They can negatively impact chemical parameters such as pH and DO. Mechanical filtration (physical screens and barriers) will be the first important step in monitoring to enable the efficient removal of particulate matter. Visual inspection of the screens and filters is often the best method for checking for large particles. It is important that the particles are removed quickly, in order to prevent them from breaking down into smaller pieces, which would increase the time needed for them to be removed and would lead to increased oxygen demand due to an increased nutrient load (Thorarinsdottir et al. 2015). The screens should be cleaned frequently to ensure that the debris is removed.

Introduction

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More than 150 different vegetables, herbs, and flowers have been grown successfully in aquaponic systems. Plants suited to aquaponic systems are typically fast growing, have shallow root systems, and a low nutrient demand, such as leafy greens and herbs. Fruiting vegetables, such as tomatoes, cucumbers and peppers, also do well but they have higher nutrient demands and are more appropriate for established systems with adequate fish stocks. But there are some plants that don’t grow well, some that don’t make sense in terms of economics, and some that probably won’t work well due to space restrictions. Root crops, such as potatoes, sweet potatoes, turnips, onions, garlic, and carrots, typically do better in traditional culture, though they can be grown successfully in deep media beds (Somerville et al. 2014a).

Introduction to aquaculture

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Aquaculture is the captive rearing and production of fish and other aquatic animal and plant species under controlled conditions (Somerville et al. 2014). Due to overfishing and the consequent decline of wild fish stocks, aquaculture has become increasingly important in the past few decades (Figure 1), and may become even more so in the future as wild fish stocks face immense pressure from climate change (Gibbens 2019).

Figure 2: In 2016 aquaculture accounted for around 47% of total global fish production (FAO 2018)

Introduction to aquaponic technology

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Today, as a result of rapid population growth, increased food requirements and urbanization, the amount of agricultural land is rapidly declining and our oceans are overfished. To meet future demands for food, there is a need for innovative, space-saving, and ecological food production technologies. Aquaponics is a polyculture (integrated multi-trophic production system) consisting of two technologies: aquaculture (a fish farm) and soil-less (hydroponic) cultivation of vegetables. The primary goal of aquaponics is to reuse the nutrients contained in fish feed and fish faeces in order to grow crops (Graber & Junge 2009; Lennard & Leonard 2004; Lennard & Leonard 2006; Rakocy et al. 2003). The integration of two systems into one removes some of the unsustainable factors of running aquaculture and hydroponic systems independently (Somerville et al. 2014).

Introduction to hydroponics

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The principles of hydroponics

Hydroponics is a method for growing crops without the use of soil, and with nutrients added to the irrigation water (so called fertigation) (Figure 1). The main differences between traditional in-ground growing techniques and soil-less techniques concern the relative use of water and fertilizer, and overall productivity. Soil-less agriculture is also typically less labour-intensive, supports monocultures better than in-ground agriculture, and can be used on non-arable land (Somerville et al. 2014c).

Introduction to monitoring

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Scientific parameters

A scientific parameter is a definable or measurable characteristic or a value, selected from a set of data. A variable is any factor, trait, or condition that can exist in differing amounts or types. In experimental science, there are usually three types of variables: 1) independent, 2) dependent, and 3) controlled. The independent variable is the one that the experimenter changes in order to measure or observe a response or an effect. The dependent variable is the measured response to the changes made to the independent variable. The controlled variables are the variables which are kept constant in an experiment.

Introduction to urban agriculture

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Urban agriculture takes many forms. These can range from household, school and community gardens to rooftop and indoor farms. A fundamental distinction is often made between urban agriculture (involving food production in an urban area) and peri-urban agriculture, which occurs on the fringes of cities. In the case of the latter, farming is largely undertaken by professional farmers on land that has often already been used for farming for decades. An urban farm is a part of a local food system where food is cultivated and produced within an urban area, and marketed to consumers predominantly within that urban area. Besides growing fruit and vegetables, urban farming can also include animal husbandry, beekeeping, aquaculture, and non-food products such as producing seeds, cultivating seedlings, and growing flowers. It can be characterized in terms of the geographic proximity of a producer to the consumer, and sustainable production and distribution practices. Urban farms can take a variety of forms, including non-profit gardens and for-profit businesses. They can provide jobs, job training, and health education, and they can contribute to better nutrition and health for the community by providing locally grown, fresh produce (McEldowney 2017). This chapter focuses on commercial food production within urban areas and, specifically, on rooftop greenhouses and other types of indoor farms.

Legal framework

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The goal of the food safety policy of the EU is to ensure safe and nutritious food from healthy animals and plants while supporting the food industry (EC 2014). The integrated Food Safety policy also includes animal welfare and plant health. In the strategy for animal welfare there is an action on the welfare of farmed fish, though there are no specific rules in place (EC 2012). Because of the great variety of potential produce, food safety norms are not explicit for aquaponic produce and there are no specific EU regulations yet (Joly et al. 2015). Aquaponics falls under the common EU policies related to agriculture, fisheries, food safety and the environment. Because aquaponics includes both fish and plant production, different policies apply. Like aquaculture operators, aquaponic producers use a shared primary resource (water) and generate effluents, and their activities are subject to a significant amount of policies and legislation (Hoevenaars et al. 2018; Joly et al. 2015). Table 2 lists the key EU regulations on food safety.

Legislation and governance

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A range of factors – existing urban layout, perceptions and attitudes towards the use of urban space, and the prevalent political climate – all operate at the city-specific level to influence the development of urban agriculture. In most countries in the Global North there is no independent category for urban agriculture in municipal zoning plans, as agriculture has historically been regarded as a rural activity by urban planners. Urban agriculture in Europe appears to fall between different policy areas, despite assurances from the European Commission that Member State rural development programmes can be used for the benefit of urban agriculture. To some, it may not be sufficiently agricultural in nature to secure support under Pillar I of the Common Agricultural Policy (as typified by more conventional agriculture). To others, it is not considered sufficiently rural to secure support under the above-mentioned rural development programmes. Looking to the future, the challenge for urban agriculture is how to achieve the necessary integration across all EU policy areas over the next programming period, post-2020 (McEldowney 2017). The urban agriculture sector in Europe is therefore characterized by bottom-up initiatives, which are informal and non- institutionalized. Although urban agriculture is beginning to be recognised at the institutional level in some countries, there is still a lack of public policy focusing directly on it. Urban agriculture is generally considered to be the responsibility of local governments, but since a formal framework is often missing, support at local government level has the tendency to be informal and fragmented. For example, The London Plan, which is the spatial development strategy for the Greater London area, simply states that the boroughs should identify potential sites that could be used for commercial food production in their development plans. With an appropriate policy framework, initiatives could become better grounded and secured. The inclusion of building-integrated agriculture in urban development policies or urban planning framework plans would boost its importance for urban development. For example, modifying zoning codes – by allowing food growing activities in certain categories, or adopting a formal urban agriculture land use zone –, recognizing urban agriculture as an economic development strategy, facilitating land access, and eliminating restrictions that stem from other policy fields, could all impact positively on the development of urban agriculture (Prové et al. 2016).

Living walls

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Living walls are often used in architecture to provide aesthetic, ecological and environmental benefits in urban areas. The modular panels, comprised of polypropylene plastic containers or geotextile mats, support plants which provide benefits not only in visual terms, but also with regards to amenity, biodiversity, thermal efficiency and amelioration of air pollutants, all for a very small ground level footprint (Manso & Castro-Gomes 2015; Perini et al. 2013).

Two universities have been investigating the potential for living walls for growing edible crops using aquaponics. A series of experiments were conducted at the University of Greenwich, UK, to identify the most suitable type of system, and the best growing medium (Khandaker & Kotzen 2018). The first experiment used a Terapia Urbana Fytotextile living wall panel. This semi-hydroponic modular panel system is made from a patented geotextile fabric composed of three layers of synthetic and organic material including PVC, Fytotextile and Polyamide. Each square metre holds up to 49 plants in individual pockets. Depending on the vegetable species grown, approximately 98 plants/m² can therefore be grown using back-to-back elements of this living wall system, compared with 20-25 leafy greens per square metre in a horizontal system. The felt panel was attached to an east-facing external wall, and planted with seven different plants (spinach, basil, chicory, asparagus pea, lettuce, mint and tomato) in seven different growing media (horticultural-grade mineral wool, vermiculite, charcoal, coconut fibre, sphagnum moss, pond grown algae, and straw). Each plant species was arranged vertically in columns, and the growing medium was arranged horizontally in rows (Figure 18). Water was pumped up to an internal drip irrigation pipe from a surrogate aquaponics tank with added hydroponic nutrients. The water then flowed down the back of the panel where it was made available to the substrate and the plant roots. Excess water dripped from the bottom of the living wall panel into a gutter and then back to the water tank (Khandaker & Kotzen 2018).

Macro- and micronutrients

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The elements of the universe

There are 92 naturally occurring elements on the Earth. Some are very well studied, some not at all: for example astatine (Bryson 2003). The problem is that some elements are very rare. For example, only 24.5 grams of francium occur at any time in the whole of the Earth’s crust. Only about 30 of the naturally occurring elements are widespread on Earth, and very few are important for life (Figure 1). In the solar system, stars in general, and probably the universe as a whole, the most abundant elements are the lighter elements: over 75% hydrogen (H), 25% helium (He), about 1% everything else. In the ‘everything else’ category even numbered elements are more abundant than odd numbered elements. Abundance tends to fall rapidly with increasing atomic number. However, carbon (C), oxygen (O), magnesium (Mg), silicon (Si), and iron (Fe) are anomalously high relative to these general trends, while lithium (Li), beryllium (Be), and boron (B) are anomalously low. In the Earth’s crust the order of abundance is O (< 50%), Si (> 20%), Al, Fe, Mg, Ca, Na, and K. These are all the sorts of elements that rocks are mostly made out of. In the Earth as a whole, because of the core and the mantle, Fe, Ni, and Mg, become more common, while O, Si, Al remain major overall constituents (Table 1). Concerning life, elements have different functions (Table 2). We have evolved to utilize or tolerate the elements, but we live within narrow ranges of acceptance. As a rule, our tolerance for elements is directly proportionate to their abundance in the Earth’s crust (Bryson 2003).

Main interactions between ingestion and environmental factors

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As commented above, we should be able to house each species according to its requirements. For that we first need a profound knowledge of the species that we are going to work with before we begin to grow the fish or start the installation. Once we have this information, we should be able to maintain the adequate housing conditions in our system, which in this case is related to aquaponic systems.

Management of recirculating aquaculture system (RAS)

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Stocking density

Stocking density is a very important factor that has to be decided in advance when designing a RAS. Stocking density can be defined in different ways (Table 2), and it is important to be aware when and why different definitions are being used.

Table 2: Stocking density definitions

Density of individuals		Biomass density
per surface (#/m²)	per volume (#/m³)	per surface (kg/m²)	per volume (kg/m³)
Independent of tank depth. Relevant for bottom-dwelling fish	Is often high for small fishes even though the biomass density is higher	Independent of tank depth. Relevant for bottom-dwelling fish. It is often higher for bigger fish than for smaller species	Relevant for free swimming species

Different fish species have different possible stocking densities. Density is a central factor in determining fish welfare, although all the biological aspects are not clear yet. There are fish species that have different behaviour at different densities. For example, tilapia adopts schooling behaviour at high densities, and territorial behaviour at low densities. In order to prevent fish harming each other, they therefore have to be farmed at a certain density. To use space efficiently, and to prevent cannibalism, a fish tank should contain fish of approximately the same size. This means (a) that an aquaculture facility should have several tanks to house fish of different size classes, and (b) that the fish population has to be graded according to size occasionally, and redistributed into the tanks. Low and high stocking densities in aquaculture systems have several consequences for the management of a RAS (Table 3).

Nutrient supply in aquaponics

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The chemical composition of system water in aquaponics is very complex. Besides a large array of dissolved ions, it contains organic substances resulting from the release of products of fish metabolism and feed digestion, as well as substances excreted by the plants. These substances are largely unknown, and their interactions can further influence the chemical composition and pH of aquaponic nutrient solutions. All this can exert manifold, but mostly yet unknown, effects on the nutrient uptake by plants, on fish health, and on microbial activity.

Operating an aquaponic system

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Basic system maintenance and operation procedures

To ensure that the aquaponic system is running well one should prepare clear operating, maintenance and troubleshooting instructions (manuals), and also checklists of daily, weekly and monthly activities for which records should be kept. This way, different staff members will always know what to do. All observations and tasks performed need to be entered (with specific dates) in a dedicated record book, that must be stored in a visible place. It is especially important to record the chemical and physical parameters of the water, and any changes in the appearance and behaviour of the fish (score sheet). Table 9 lists basic system maintenance and operating procedures.

Planning the recirculating aquaculture part for an aquaponic system

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In aquaponics, it is very important that the input and output of nutrients is in balance over the entire plant growing period. This balance can mainly be controlled using two different approaches:

Approach 1: An existing recirculating aquaculture system (RAS) is used to dimension the corresponding hydroponic unit with plants (Figure 12). This approach is covered by the Exercise in Module 5 (nutrient water balance).
Approach 2: The RAS is dimensioned based on the desired plant and fish production (Figure 13). This is covered by the in Exercise in Module 2.

Plant anatomy, physiology and growing requirements

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Plant anatomy

Plant anatomy describes the structure and organization of the cells, tissues and organs of plants in relation to their development and function. Flowering plants are composed of three vegetative organs: (i) roots, which function mainly to provide anchorage, water, and nutrients, and to store sugars and starch; (ii) stems, which provide support; and (iii) leaves, which produce organic substances via photosynthesis. The roots grow down in response to gravity. In general, a seedling produces a primary root that grows straight down and gives rise to secondary lateral roots. These may produce tertiary roots, which in turn may branch, with the process continuing almost indefinitely. Growth occurs at the root tip or apex, which is protected by a root cap. Roots grow and branch continually, in their search for minerals and water. The efficiency of the root as an absorbing organ depends on its absorptive surface area relative to its volume, which is created by the root hairs and the complex system of branches.

Plant nutrition

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Essential nutrient elements

Plants require 16 (Resh 2013) or according to other sources 17 (Bittszansky et al. 2016) essential nutrient elements without which they are unable to complete a normal life cycle. Plants require essential nutrients for normal functioning and growth. A plant’s sufficiency range is the range of nutrient amount necessary to meet the plant’s nutritional needs and maximize growth. The width of this range depends on individual plant species and the particular nutrient. Nutrient levels outside of a plant’s sufficiency range cause overall crop growth and health to decline due to either a deficiency or toxicity.

Plant selection

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This section covers some of the plant species most commonly grown in aquaponic systems. Details are provided on the ideal growing conditions, the length of the growing cycle, common pests and diseases, and recommendations for harvesting and storage. Many varieties of vegetables are available from seed houses. While both field and greenhouse varieties can be grown in a greenhouse, it is advantageous to use greenhouse varieties whenever possible, since they have often been bred to yield very heavily under controlled environmental conditions (Resh 2013).

Prevention methods in integrated pest management

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Good plant health is not only the absence of diseases and pests. Good cultivation techniques with adequate nutrition, water quality, climate conditions and production hygiene are required for healthy growth. To achieve sustainable plant protection management, it is essential to understand how to minimize the risk of plant diseases and pests. Prevention is the most important part of integrated pest management (Table 2).

Table 2: Plant disease prevention measures in aquaponics

Production plan and monitoring the evolution of the farm

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All aquaponic farms need well defined production goals and a plan to fulfil those goals. Specifically, it is helpful to define the following aspects well in advance:

The species to be used
The size of fingerlings needed initially and the target size of the adults to be sold at the end. This will help to define the productive cycles on the farm (types of tanks, etc.)
The optimal densities and housing conditions for each stage of growth. This will help to define the maximum load of live biomass in the installation, and annual production

Proximate composition of fish feeds and essential nutrients

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When research began on fish feeds more than 50 years ago, scientists first analysed the natural diets of the species in question. Trout, as an example of a carnivorous fish, had a natural diet that consisted of 50% protein, 15% fat, 8% fibre, and 10% ash, which is high in protein compared to terrestrial mammals. Ever since then researchers have been trying to find the right balance of protein, carbohydrates, fats, fibre, vitamins and minerals for fish used in aquaculture (Bhilave et al. 2014).

Recirculating aquaculture system (RAS) technology

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A recirculating aquaculture system (RAS) consists of fish tanks and several filtration units which clean the water. In a classic RAS the water is thereby in constant flow from the fish tanks through the filtration system and then back to the fish tanks (Figure 4). Due to the metabolism of the fish, the water that leaves the tanks contains high concentrations of solids, nutrients, and carbon dioxide, whilst it is oxygen-poor compared to inflowing water. The goal of the filtration units is to decrease the solids, nutrients, toxins, and carbon dioxide concentrations, and increase the levels of dissolved oxygen in the water before it is returned to the fish tank.

Respiration physiology

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The air we breathe is mostly nitrogen (78%) and 21% oxygen. The water that fish ‘breathe’ also contains oxygen, but at a much lower concentration, less than 1%. In addition, since water is 840 times denser than air and 60 times more viscous, it takes more effort for fish to ‘breathe’ to extract oxygen, around 10% of their metabolic energy. In comparison, terrestrial animals only use about 2% of their metabolic energy to extract oxygen from air. For example, rainbow trout need to move approximately 600 ml of water past their gills per minute per kg weight while, in comparison, terrestrial reptiles such as turtles only need to move 50 ml air min^-1 kg^-1. As a result, even though fish gills are quite efficient, obtaining enough oxygen from the surrounding water can be difficult and sometimes life threatening.

Scientific research methodology applied to aquaponics

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The following case studies illustrate some of the different kinds of methodologies that can be used for research relating to aquaponics. The first case study is an example of social science research conducted using a questionnaire. A questionnaire is a tool for collecting and recording information about a particular issue of interest in a standardized manner. The information from questionnaires tends to fall into two broad categories – facts and opinions; very often they include questions about both. The questions may be unstructured or structured or, as in the case study below, a combination of both. Unstructured questions ask respondents to provide a response in their own words, while structured questions ask respondents to select an answer from a given set of choices. Structured questionnaires are usually associated with quantitative research, i.e. research that is concerned with numbers (how many? how often? how satisfied?). The responses to individual questions in a structured questionnaire may be aggregated and used for statistical analysis (Nayak & Singh 2015).

Solids separation

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The following decisions need to be made during the design stage:

Is a separate solid removal step necessary? In systems with a low fish stocking rate, a media growing bed can remove solids and act as a biofilter. However, over time, clogging and anaerobic areas will occur as the amount of solids increases.
What is the appropriate device for solids removal? Waste particles in the water can be of different sizes, which affects the technologies used to remove them. Systems with a lower stocking density (<10 kg/m³) may be able to use devices based on sedimentation for particle removal, while systems with a higher stocking density (>10 kg/m³) may need rotational drum filters (Figure 7).

Stacked horizontal beds

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In this type of system, horizontal grow beds are stacked vertically in tiers. This arrangement means that in a greenhouse, only the upper bed will be facing direct natural light, and supplementary lighting needs to be provided for the lower beds, usually from lights attached to the base of the bed above. While in principle this means that the grow beds could be stacked as high as the greenhouse or production unit allows, in practice growing at height means that the system is more difficult to manage, requiring the use of scissor lifts for planting, maintenance and harvesting, and additional energy to pump the water to all levels. The shorter the stature of the crop, the more tiers can be inserted into the system, which means that most stacked horizontal beds are used for growing microgreens. The grow beds may be DWC, NFT or media beds. For example, in the UK Hydrogarden produces various models of the V-Farm: the four and five tier NFT system suitable for herbs, leafy greens and strawberries can grow up to 35 plants/m², while the five tier flood and drain system can grow 4.6 m² of microgreens on a footprint of 1m².

Starting to design an aquaponic system

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Do not be confused by the great variety of designs for aquaponic systems which you may encounter in the literature or by browsing the web. When planning and building an aquaponic system, it is necessary to follow the basic principles in order for the system to function properly. There are big differences between systems in terms of investment costs, maintenance and operating costs, reliability, health and safety, potential for fish and crop growth, and total workload. It is therefore necessary to define all these aspects during the design phase.

The biofilter

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The biofilter is the heart of every recirculating aquaculture system. Fish health, and therefore economic success, depend on correct operation of the biofilter. High ammonia and nitrite levels in fish tanks can be caused by several factors. One of these can be poorly designed or sub-optimal operation of the biofilter (too small, not mixed evenly, nitrate levels too high, pH too low, intoxication of the biofilter by salt or medical treatment, aeration too low or too high, etc.). The other main aspect of design failure is insufficient recirculation of the water. The biofilter can only degrade what it receives from the fish tank. If the recirculation rate is too low, even an over dimensioned biofilter will not lead to good water quality. To avoid this, follow the example in Chapter 2 to calculate the correct recirculation rate for your system.

The biogeochemical cycles of major nutrients in aquaponics

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The nitrogen cycle

Nitrogen is an essential element for all living organisms and is the main nutrient of concern in aquaponics. It occurs in amino acids (parts of proteins), nucleic acids (DNA and RNA), and in the energy transfer molecule adenosine triphosphate (Pratt & Cornely 2014). As nitrogen occurs in many chemical forms, the nitrogen cycle is very complex (Figure 3).

Figure 3: The general form of nitrogen cycle (Encyclopaedia Britannica)

The concept of integrated pest management (IPM)

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Many national and intergovernmental bodies have firmly decided that the officially endorsed paradigm for crop protection is ‘integrated pest management’ (IPM). For example, a European Union (EU) Directive (The European Parliament and the Council of Europe 2009) has obliged all professional plant growers within the Union to apply the general principles of IPM since 2014. IPM is an ecosystem-based strategy that focuses on the long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and the use of resistant varieties (Tang et al. 2005). Although aquaponics is understood to be more resilient against pathogens when compared with conventional hydroponic production (Gravel et al. 2015), it is nevertheless impossible to avoid pests and diseases. Healthy crops are first and foremost the consequence of good growth conditions and choosing an appropriate plant variety, which allow plants to achieve their high productive potential, and not the result of chemical and biological plant protection. A higher microbial diversity improves plant resistance in the rhizosphere against root diseases as well as greater nutrient uptake by the crop. Therefore, optimal plant nutrition, proper environmental conditions in the cultivation system, and intelligent cultivation techniques are essential. The management of pests and pathogens ought to minimize the application of biological and chemical products.

The fish tank

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The basic components to consider are fish tanks, the sludge removal unit, the biofilter, the sump, plant beds, pumps, and piping. The function, required materials, and location of each of these, and their interaction with other components, all need to be considered. The interaction among the components, for example, will determine the number of pumps that will be required.

The fish tank will be the home of the fish for a relatively long period of time, so it should be chosen with care. The materials, design and size of the fish tank are all important, and should enable relatively easy observation and handling of fish, removal of solid particles, and good water circulation (simulation of natural water flow).

The grow beds

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Water flow and positioning of the grow beds

Water flow is the most important part of proper system design, and the exact positioning of the grow beds has a major impact on this. Therefore it should be considered carefully and, if possible, an expert should be consulted. The grow beds should be positioned after the biofilter and before the water is recirculated to the fish tank. Consider how the water will flow from the grow bed into the fish tank. If it is by gravity, then the water level in the grow bed must be higher than the fish tank, which may mean that you have to dig the tank and connections into the ground, or that your grow beds will be so high that you would not be able to work comfortably. Usually, a sump tank with a pump is placed after the grow bed to enable water to be pumped into the fish tank. The connection between the biofilter and the grow beds should be as short as possible, and the inlet/outlet should be placed on the opposite sides of each grow bed. One of the advantages of soilless cultures is the possibility to design suitable conditions for working with plants. Ideally, the system should be designed at a height that enables you to monitor the plants easily (Figure 18).

The most common pests and diseases

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Identification of pests and diseases

Proper identification of pests and diseases is important. Whether the pest is an insect, rodent, phytopathogenic fungus, or other organism, correct identification makes controlling it easier and more effective. A mistake in identification can lead to improper control tactics that cost time and money. It may also lead to unnecessary risks to people, to the fish, or to the environment. To identify a potential disease, one should follow the steps described in Figure 5 and 6. Sometimes disease symptoms are similar to plant nutrient deficiency symptoms. In case of doubt, one should consult a specialist. If this is not possible, describe the symptoms and take photos (which will also serve for future reference). Then search on the internet to find photos and descriptions of disease symptoms that match those of your plants.

The potential of aquaponics for the wellbeing of elderly citizens

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Aquaponics may provide an optimal environment to reach several therapeutic goals in a variety of clients with cognitive and/or physical disabilities, and special population groups like the elderly, children, or developmentally challenged people. The therapeutic goals of health care professionals such as occupational therapists and physiotherapists are the promotion of and/or treatment for wellbeing.

The primary goal of occupational therapy is to enable people to participate in the activities of everyday life. Occupational therapists achieve this by working with people and communities to enhance their ability to engage in the occupations they want, need, or are expected to do, or by modifying the occupation or the environment to better support their occupational engagement (WFOT 2012). In occupational therapy, occupations refer to the everyday activities that people do as individuals, in families, and with communities to occupy time and bring meaning and purpose to life. Occupations include things people need to, want to and are expected to do (WFOT 2012).

The sustainability of commercial indoor urban farms

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Supplying urban populations with locally grown food is widely viewed as a more resource-efficient alternative to the conventional supply chain using food grown in peri-urban or remote rural locations. Indoor, soilless cultivation in urban areas is portrayed as a particularly sustainable solution, by reducing food miles, minimizing land use and water consumption, and improving yields. However, to ensure optimal growing conditions for the crops, controlled-environment farms all rely on the artificial control of light, temperature, humidity and water cycles, and can therefore be highly energy intensive, depending on local climatic conditions and the specific characteristics of the host building. The carbon emissions of urban farms should therefore be carefully weighed against potentially reduced emissions, such as those from transporting food from rural and peri-urban farms. The elevated economic costs of urban farms, both in terms of infrastructure and operational costs, also need to be carefully assessed before undertaking such a venture.

Types of feeds

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In Europe, intensive aquaculture began at the end of the 19th century, when governments decided to breed fish to obtain fingerlings which were used to restock lakes and rivers (Polanco & Bjorndal 2018). Those fish represented an important source of protein for river communities, and helped to alleviate hunger. Efforts were made to promote the most appreciated species, such as salmonids, which are carnivorous. As production increased and fish were kept under intensive care for longer periods, farmers began to formulate feeds. In the beginning they captured macroinvertebrates in nearby water bodies, but that was seasonal and in limited supply. Later, fish were fed using waste products from slaughterhouses, which were chopped up into small pieces and thrown in the water directly. As a result, many salmon farms were established close to slaughterhouses.

Typology of commercial indoor urban farms

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Building-integrated agriculture (BIA) predominantly uses soilless cultivation techniques such as hydroponics, aquaponics or aeroponics. The benefits of BIA include year-round production, higher yields, greater control of food safety and biosecurity, and substantially reduced inputs with respect to water supply, pesticides, herbicides, and fertilizers, as well as improved building energy efficiency through the creation of symbiotic relations between the farm and its host building. BIA systems can be applied either on the building envelope – on the rooftop or facades, to take advantage of the availability of natural light – or indoors with artificial light, or in a free-standing building (Figure 2), and all the growing parameters are controlled. This is known as Controlled-Environment Agriculture, or CEA, which combines horticultural and engineering skills in order to optimize crop production, crop quality and production efficiency.

Urban agriculture business models

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There are many different types of model for the successful operation of a business. A business model is a strategy for how a company will make a profit. It identifies the products or services the business will sell, the target market, and the anticipated expenses. A new business in development needs to have a business model in order to attract investment, help it recruit talent, and motivate management and staff. Established businesses have to revisit and update their business plans regularly in order to anticipate trends and challenges ahead. Jan Wilhelm van der Schans, of Wageningen University, identifies five types of urban agriculture business model (van der Schans 2015; van der Schans et al. 2014):

What is science, what is research? Basic terms

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General definitions

Science

The word ‘science’ comes from the Latin word scientia, which means knowledge. Science refers to systematic and organized knowledge in any area of investigation that has been obtained using the ‘the scientific method’. The scientific method is the best method we have, to obtain reliable data about the world, which helps both to explain and predict different phenomena. Science is based on observable and measurable things/phenomena. However, there is no absolute scientific truth; it is just that some knowledge is less likely to be wrong than others (Nayak & Singh 2015). Statements produced through scientific research must be testable, and research by itself must be reproducible (a good scientific paper is one which enables the method to be replicated).

A Vision of Aquaponics with Brian Filipowich

Mon, 31 Aug 2020 00:00:00 +0000

It is a rare skill to lead an organization like the Aquaponics Association in the midst of a global pandemic and in the face of an emerging market. Brian Filipowich has taken on this challenge as the Chairman of the Aquaponics Association and is also the Director of Anacostia Aquaponics in Washington, DC. He has worked for the U.S. Senate on banking and financial policy until 2015, then did a career one-eighty into aquaponics and sustainable agriculture. He currently lives in Washington, DC with his wife, daughter, cat, about 10 koi, and lots of plants.

Reese Hundley: A passionate educator at Symbiotic Aquaponic

Mon, 31 Aug 2020 00:00:00 +0000

We recently did an interview with one of the key players at Symbiotic Aquaponic, Reese Hundley. They are experts at system design and share our passion for impacting communities with aquaponics. Reese has a rich story to tell.

What would you say is your “Aquaponic Superpower”?

Taking raw materials and then turning them into a configuration that I can provide to someone and teach them to help themselves and be a steward of life. I find it highly rewarding to give people the power to support life and their communities in an environmentally responsible manner. Our service allows individuals, families, and communities to access the healthiest of foods in a way that promotes healthy lives while connecting people to the earth and their food directly. As a result, people come together to provide for the needs of today while protecting our needs in the future.

A brief history of modern aquaponic technology

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The concept of using faecal waste and overall excrements from fish to fertilize plants has existed for millennia, with early civilizations in both Asia and South America applying this method. Through the pioneering work of the New Alchemy Institute and other North American and European academic institutions in the late 1970s, and further research in the following decades, this basic form of aquaponics evolved into the modern food production systems of today. Prior to the technological advances of the 1980s, most attempts to integrate hydroponics and aquaculture had limited success. The 1980s and 1990s saw advances in system design, biofiltration and the identification of the optimal fish-to-plant ratios that led to the creation of closed systems that allow for the recycling of water and nutrient buildup for plant growth. In its early aquaponic systems, North Carolina State University (United States of America) demonstrated that water consumption in integrated systems was just 5 percent of that used in pond culture for growing tilapia. This development, among other key initiatives, pointed to the suitability of integrated aquaculture and hydroponic systems for raising fish and growing vegetables, particularly in arid and water poor regions.

Acclimatizing fish

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Acclimatizing fish into new tanks can be a highly stressful process for fish, particularly the actual transport from one location to another in bags or small tanks (Figure 7.13). It is important to try to remove as many stressful factors as possible that can cause fatality in new fish. There are two main factors that cause stress when acclimatizing fish: changes in temperature and pH between the original water and new water; these must be kept to a minimum.

Applicability of aquaponics

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Aquaponics combines two of the most productive systems in their respective fields. Recirculating aquaculture systems and hydroponics have experienced widespread expansion in the world not only for their higher yields, but also for their better use of land and water, simpler methods of pollution control, improved management of productive factors, their higher quality of products and greater food safety (Box 1). However, aquaponics can be overly complicated and expensive, and requires consistent access to some inputs.

Aquaculture

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Aquaculture is the captive rearing and production of fish and other aquatic animal and plant species under controlled conditions. Many aquatic species have been cultured, especially fish, crustaceans and molluscs and aquatic plants and algae. Aquaculture production methods have been developed in various regions of the world, and have thus been adapted to the specific environmental and climatic conditions in those regions. The four major categories of aquaculture include open water systems (e.g. cages, long- lines), pond culture, flow-through raceways and recirculating aquaculture systems (RAS). In a RAS (Figure 1.4) operation water is reused for the fish after a cleaning and a filtering process. Although a RAS is not the cheapest production system owing to its higher investment, energy and management costs, it can considerably increase productivity per unit of land and is the most efficient water-saving technology in fish farming. A RAS is the most applicable method for the development of integrated aquaculture agriculture systems because of the possible use of by-products and the higher water nutrient concentrations for vegetable crop production. Aquaponics has been developed from the beneficial buildup of nutrients occurring in RASs and, therefore, is the prime focus of this manual.

Aquaponics

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Aquaponics is the integration of recirculating aquaculture and hydroponics in one production system. In an aquaponic unit, water from the fish tank cycles through filters, plant grow beds and then back to the fish (Figure 1.5). In the filters, the fish wastes is removed from the water, first using a mechanical filter that removes the solid waste and then through a biofilter that processes the dissolved wastes. The biofilter provides a location for bacteria to convert ammonia, which is toxic for fish, into nitrate, a more accessible nutrient for plants. This process is called nitrification. As the water (containing nitrate and other nutrients) travels through plant grow beds the plants uptake these nutrients, and finally the water returns to the fish tank purified. This process allows the fish, plants, and bacteria to thrive symbiotically and to work together to create a healthy growing environment for each other, provided that the system is properly balanced.

Balancing the aquaponic ecosystem

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The term balancing is used to describe all the measures an aquaponic farmer takes to ensure that the ecosystem of fish, plants and bacteria is at a dynamic equilibrium. It cannot be overstated that successful aquaponics is primarily about maintaining a balanced ecosystem. Simply put, this means that there is a balance between the amount of fish, the amount of plants and the size of the biofilter, which really means the amount of bacteria. There are experimentally determined ratios between biofilter size, planting density and fish stocking density for aquaponics. It is unwise, and very difficult, to operate beyond these optimal ratios without risking disastrous consequences for the overall aquaponic ecosystem. Advanced aquaponic practitioners are invited to experiment and adjust these ratios, but it is recommended to begin aquaponics following these ratios. This section provides a brief, but essential, introduction to balancing a system. Biofilter sizes and stocking densities are covered in much greater depth in Chapter 8.

Basic plant biology

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This section comments briefly on the major parts of the plant and then discusses plant nutrition (Figure 6.3). Further discussion is outside the scope of this publication, but more information can be found in the section on Further Reading.

Basic plant anatomy and function

Roots

Roots absorb water and minerals from the soil. Tiny root hairs stick out of the root, helping the absorption process. Roots help to anchor the plant in the soil, preventing it from falling over. Roots also store extra food for future use. Roots in soil-less culture show interesting differences from standard in-ground plants. In soil-less culture, water and nutrients are constantly supplied to the plants, which are facilitated in their nutrient search and can grow faster. Root growth in hydroponics can be significant for the intense uptake and the optimal delivery of phosphorus that stimulates their growth. It is worth noting that roots retain almost 90 percent of the metals absorbed by the plants, which include iron, zinc and other useful micronutrients.

Comparing aquaponic techniques

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Table 4.2 below provides a quick reference and comparative summary of the various aquaponic culture systems described above.

TABLE 4.2

Strengths and weaknesses of main aquaponic techniques

System type

Strengths

Weaknesses

Media bed units

Source: Food and Agriculture Organization of the United Nations, 2014, Christopher Somerville, Moti Cohen, Edoardo Pantanella, Austin Stankus and Alessandro Lovatelli, Small-scale aquaponic food production, http://www.fao.org/3/a-i4021e.pdf. Reproduced with permission.

Component calculations and ratios

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Aquaponic systems need to be balanced. The fish (and thus, fish feed) need to supply adequate nutrients for the plants; the plants need to filter the water for the fish. The biofilter needs to be large enough to process all of the fish wastes, and enough water volume is needed to circulate this system. This balance can be tricky to achieve in a new system, but this section provides helpful calculations to estimate the sizes of each of the components.

Current applications of aquaponics

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This final section briefly discusses some of the major applications of aquaponics seen around the world. This list is by no means exhaustive, but rather a small window into activities that are using the aquaponic concept. Appendix 6 includes further explanation as to where and in what contexts aquaponics is most applicable.

Domestic/small-scale aquaponics

Aquaponic units with a fish tank size of about 1 000 litres and growing space of about 3 m² are considered small-scale, and are appropriate for domestic production for a family household (Figure 1.6). Units of this size have been trialled and tested with great success in many regions around the world. The main purpose of these units is food production for subsistence and domestic use, as many units can have various types of vegetables and herbs growing at once. In the past five years, aquaponic groups, societies and forums have developed considerably and served to disseminate advice and lessons learned on these small-scale units.

Deep water culture technique

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The DWC method involves suspending plants in polystyrene sheets, with their roots hanging down into the water (Figures 4.68 and 4.69). This method is the most common for large commercial aquaponics growing one specific crop (typically lettuce, salad leaves or basil, Figure 4.70), and is more suitable for mechanization. On a small-scale, this technique is more complicated than media beds, and may not be suitable for some locations, especially where access to materials is limited.

Essential components of an aquaponic unit

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All aquaponic systems share several common and essential components. These include: a fish tank, a mechanical filter, a biofilter, and hydroponic containers. All systems use energy to circulate water through pipes and plumbing while aerating the water. As introduced above, there are three main designs of the plant growing areas including: grow beds, grow pipes and grow canals. This section discusses the mandatory components, including the fish tanks, mechanical filter, biofilter, plumbing and pumps. The following sections are dedicated to the separate hydroponic techniques, and a comparison is made to determine the most appropriate combination of techniques for different circumstances.

Examples of small-scale aquaponic setups

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Aquaponics has been used successfully in a wide range of locations. Moreover, aquaponic techniques have been revised to meet diverse needs and goals of farmers beyond the common IBC or barrel methods (described throughout this publication). There are many examples, but these were chosen to highlight the adaptability and diversity of the aquaponic discipline.

Aquaponics for livelihood in Myanmar

A pilot-scale aquaponic system was built in Myanmar to promote micro-scale farming during the implementation of an e-Women project funded by the Italian Development Cooperation. The goal was to create a productive unit under low-tech and low-cost criteria by using locally available materials and stand-alone solar energy. The system hosted tilapia and a wide range of vegetables (Figure 9.17). The system was used for the development of a cost-benefit analysis, inclusive of depreciation, for household- scale systems with the objective to meet the daily income target of USD1.25 set by the Millennium Development Goal.

Fish anatomy, physiology and reproduction

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Fish anatomy

Fish are a diverse group of vertebrate animals that have gills and live in water. A typical fish uses gills to obtain oxygen from the water, while at the same time releasing carbon dioxide and metabolic wastes (Figure 7.2). The typical fish is ectothermic, or cold-blooded, meaning that its body temperature fluctuates according to the water temperature. Fish have almost the same organs as terrestrial animals; however, they also possess a swim bladder. Positioned in the abdomen, this is a vesicle containing air that keeps the animal neutrally buoyant in the water. Most fish use fins for movement and have a streamlined body for navigating through water. Often, their skin is covered with protective scales. Most fish lay eggs. Fish have well-developed sensory organs allowing them to see, taste, hear, smell and touch. In addition, most fish have lateral lines, which sense pressure differences in the water. Some groups can even detect electrical fields, such as those created by heartbeats of prey species. However, their central nervous system is not as well developed as in birds or mammals.

Fish feed and nutrition

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Components and nutrition of fish feed

Fish require the correct balance of proteins, carbohydrates, fats, vitamins and minerals to grow and be healthy. This type of feed is considered a whole feed. Commercially available fish feed pellets are highly recommended for small-scale aquaponics, especially at the beginning. It is possible to create fish feed in locations that have limited access to manufactured feeds. However, these home-made feeds need special attention because they are often not whole feeds and may lack in essential nutritional components. More on homemade feeds can be found in Section 9.11 and Appendix 5.

Fish health and disease

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The most important way to maintain healthy fish in any aquaculture system is to monitor and observe them daily, noting their behaviour and physical appearance. Typically, this is done before, during and after feeding. Maintaining good water quality, including all of the parameters discussed above, makes the fish more resistant to parasites and disease by allowing the fishes’ natural immune system to fight off infections. This section discusses briefly key aspects of fish heath, including practical methods to identify unhealthy fish and prevent fish disease. These key aspects are:

Fish selection

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Several fish species have recorded excellent growth rates in aquaponic units. Fish species suitable for aquaponic farming include: tilapia, common carp, silver carp, grass carp, barramundi, jade perch, catfish, trout, salmon, Murray cod, and largemouth bass. Some of these species, which are available worldwide, grow particularly well in aquaponic units and are discussed in more detail in the following sections. In planning an aquaponic facility it is critical to appreciate the importance of the availability of healthy fish from reputable local suppliers.

Heterotrophic bacteria and mineralization

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There is another important bacteria group, as well as other micro-organisms, involved in aquaponics. This bacteria group is generally called the heterotrophic group. These bacteria utilize organic carbon as its food source, and are mainly involved in the decomposition of solid fish and plant waste. Most fish only retain 30-40 percent of the food they eat, meaning that 60-70 percent of what they eat is released as waste. Of this waste, 50-70 percent is dissolved waste released as ammonia. However, the remaining waste is an organic mix containing proteins, carbohydrates, fats, vitamins and minerals. The heterotrophic bacteria metabolize these solid wastes in a process called mineralization, which makes essential micronutrients available for plants in aquaponics (Figure 5.2).

Hydroponics and soil-less culture

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Soil-less culture is the method of growing agricultural crops without the use of soil. Instead of soil, various inert growing media, also called substrates, are used. These media provide plant support and moisture retention. Irrigation systems are integrated within these media, thereby introducing a nutrient solution to the plants’ root zones. This solution provides all of the necessary nutrients for plant growth. The most common method of soil-less culture is hydroponics, which includes growing plants either on a substrate or in an aqueous medium with bare roots. There are many designs of hydroponic systems, each serving a different purpose, but all systems share these basic characteristics (Figure 1.3).

Important biological components of aquaponics

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As described in Chapter 1, aquaponics is a form of integrated agriculture that combines two major techniques, aquaculture and hydroponics. In one continuously recirculating unit, culture water exits the fish tank containing the metabolic wastes of fish. The water first passes through a mechanical filter that captures solid wastes, and then passes through a biofilter that oxidizes ammonia to nitrate. The water then travels through plant grow beds where plants uptake the nutrients, and finally the water returns, purified, to the fish tank (Figure 2.1). The biofilter provides a habitat for bacteria to convert fish waste into accessible nutrients for plants. These nutrients, which are dissolved in the water, are then absorbed by the plants. This process of nutrient removal cleans the water, preventing the water from becoming toxic with harmful forms of nitrogen (ammonia and nitrite), and allows the fish, plants, and bacteria to thrive symbiotically. Thus, all the organisms work together to create a healthy growing environment for one another, provided that the system is properly balanced.

Integrating aquaponics with other gardens

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Aquaponics can be used alone, but it becomes a stronger tool for the small-scale farmer when used in conjunction with other agriculture techniques. It has already been discussed how other plants and insects can be grown to supplement the fishes’ diet, but aquaponics can also help the rest of the garden. Generally, the nutrient-rich water from the aquaponic units can be shared among other plant production areas.

Irrigation and fertilization

Aquaponic units are a source of nutrient-rich water for vegetable production. This water can also be used to fertilize ornamental plants, lawns or trees. Aquaponic water is an excellent organic fertilizer for all soil-based production activities. For vegetables growing in raised beds or patches, aquaponic water can be periodically taken from the unit and irrigated onto the growing space, giving the soil a boost of essential nutrients for the vegetables. If growing larger fruiting vegetables (i.e. tomatoes) using satellite pots in the garden or in any space with good access to sunlight, aquaponic water can also be used as a nitrate-rich fertilizer during the early stages of leaf and stem development. Aquaponic water is also good for seed starting.

Maintaining a healthy bacterial colony

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The major parameters affecting bacteria growth that should be considered when maintaining a healthy biofilter are adequate surface area and appropriate water conditions.

Surface area

Bacterial colonies will thrive on any material, such as plant roots, along fish tank walls and inside each grow pipe. The total available area available for these bacteria will determine how much ammonia they are able to metabolize. Depending on the fish biomass and system design, the plant roots and tank walls can provide adequate area. Systems with high fish stocking density require a separate biofiltration component where a material with a high surface area is contained, such as inert grow media - gravel, tuff or expanded clay (Figure 2.7).

Major differences between soil and soil-less crop production

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There are many similarities between in-ground soil-based agriculture and soil- less production, while the basic plant biology is always the same (Figures 6.1 and 6.2). However it is worth investigating major differences between soil and soil-less production (Table 6.1) in order to bridge the gap between traditional in-ground practices and newer soil-less techniques. Generally, the differences are between the use of fertilizer and consumption of water, the ability to use non-arable land, and overall productivity. In addition, soil-less agriculture is typically less labour-intensive. Finally, soil-less techniques support monocultures better than does in-ground agriculture.

Management practices for fish

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Adding fish to a new aquaponic unit is an important event. It is best to wait until the initial cycling process is totally completed and the biofilter is fully functioning. Ideally, the ammonia and nitrite are at zero and nitrates are beginning to rise. This is the safest time to add fish. If it is decided to add fish before cycling, then a reduced number of fish should be added. This time will be very stressful for the fish, and water changes may be necessary. Cycling the system with fish can actually take longer than fish-less cycling.

Management practices for plants

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Seedlings can be planted into the system as soon as nitrates are detected. Expect these first plants to grow slowly and exhibit some temporary deficiencies because the nutrient supply in the water is temporarily small. It is recommended to wait 3-4 weeks to allow the nutrients to accrue. In general, aquaponic systems show a slightly lower growth rate than soil or hydroponic production in the first six weeks. However, once a sufficient nutrient base has been built within the unit (1-3 months) the plant growth rates become 2-3 times faster than in soil.

Manipulating ph

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There are simple methods to manipulate the pH in aquaponic units. In regions with limestone or chalk bedrock, the natural water is often hard with high pH. Therefore, periodic acid additions may be necessary to lower the pH. In regions with volcanic bedrock, the natural water will often be soft, with very low alkalinity, indicating a need to periodically add a base or a carbonate buffer to the water to counteract the natural acidification of the aquaponic unit. Base and buffer additions are also required for rainfed systems.

New aquaponic systems and initial management

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Building and preparing the unit

Detailed step-by-step building instructions are provided in Appendix 8. Once the unit is complete, it is time to prepare the system for routine function. Although aquaponic unit management does not require excessive time and effort, it is important to remember that a well-functioning system requires a minimum of 10-20 minutes of maintenance every day. Before stocking a new system with fish and planting the vegetables, it is crucial to ensure that all of the equipment is working properly. The most important aspects to check are the water pump, the air pump and water heaters (where applicable). It is essential to check that the NFT pipes and media beds are steady and balanced horizontally. Start running water in the system and make sure that there are no leaks or loose plumbing connections. If there are, tighten or fix them immediately. Section 9.3 provides further methods to secure the water levels and prevent catastrophic loss-of-water events. Once built, cycle the water for at least two days in order to let any chlorine dissipate. This process can be accelerated using heavy aeration. This is not necessary where the source water contains no chlorine, such as rainwater or filtered water.

Nitrifying bacteria and the biofilter

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Chapter 2 discussed the vital role of nitrifying bacteria in regard to the overall aquaponic process. The nitrifying bacteria convert the fish waste, which enters the system mainly as ammonia, into nitrate, which is fertilizer for the plants (Figure 5.1). This is a two- step process, and two separate groups of nitrifying bacteria are involved. The first step is converting ammonia to nitrite, which is done by the ammonia-oxidizing bacteria (AOB). These bacteria are often referred to by the genus name of the most common group, the Nitrosomonas. The second step is converting nitrite to nitrate is done by the nitrite-oxidizing bacteria (NOB). These are commonly referred to by the genus name of the most common group, the Nitrobacter. There are many species within these groups, but for the purposes of this publication, the individual differences are not important, and it is more useful to consider the group as a whole. The nitrification process occurs as follows:

Nutrient film technique (nft)

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The NFT is a hydroponic method using horizontal pipes each with a shallow stream of nutrient-rich aquaponic water flowing through it (Figure 4.60). Plants are placed within holes in the top of the pipes, and are able to use this thin film of nutrient-rich water.

Both the NFT and DWC are popular methods for commercial operations as both are financially more viable than media bed units when scaled up (Figure 4.61).

Other major components of water quality: algae and parasites

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Photosynthetic activity of algae

Photosynthetic growth and activity by algae in aquaponic units affect the water quality parameters of pH, DO, and nitrogen levels. Algae are a class of photosynthetic organisms that are similar to plants, and they will readily grow in any body of water that is rich in nutrients and exposed to sunlight. Some algae are microscopic, single-celled organisms called phytoplankton, which can colour the water green (Figure 3.8). Macroalgae are much larger, commonly forming filamentous mats attached to the bottoms and sides of tanks (Figure 3.9).

Plant health, pest and disease control

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Plant health has a broad meaning that goes far beyond just the absence of illnesses; it is the overall status of well-being that allows a plant to achieve its full productive potential. Plant health, including disease prevention and pest deterrence and removal, is an extremely important aspect of aquaponic food production (Figure 6.8). Although the most important advances in plant health have been achieved through the management of pathogens and pests, optimal nutrition, intelligent planting techniques and proper environmental management are also fundamental to secure healthy plants. In addition, knowledge on the specific plants grown is fundamental to addressing various production issues. Although some basic concepts on plant nutrition have already been described, this section aims to provide a far greater understanding on how to minimize the risks and to address plant diseases and pests in small-scale aquaponics.

Plant selection

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To date, more than 150 different vegetables, herbs, flowers and small trees have been grown successfully in aquaponic systems, including research, domestic and commercial units. Appendix 1 provides a technical summary of, and detailed growing instructions for, the 12 most popular herbs and vegetables. In general, leafy green plants do extremely well in aquaponics along with some of the most popular fruiting vegetables, including tomatoes, cucumbers and peppers. Fruiting vegetables have higher nutrient demands and are more appropriate for established systems with adequate fish stocks. However, some root crops and some sensitive plants do not grow well in aquaponics. Root crops require special attention, and they can only be grown successfully in deep media beds, or a version of wicking beds discussed in more detail in Section 9.3.

Planting design

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The layout of the grow beds helps to maximize plant production in the available space. Before planting, choose wisely which plants will be grown, bearing in mind the space needed for each plant and what the appropriate growing season is. A good practice for all garden design is to plan the layout of the grow beds on paper in order to have a better understanding of how everything will look. Important considerations are: plant diversity, companion plants and physical compatibility, nutrient demands, market demands, and ease of access. For example, taller crops (i.e. tomatoes) should be placed in the most accessible place within the media bed to make harvesting easier.

Product quality

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In cultured fish, particularly freshwater species, there is often the risk of off-flavour. In general, this reduction in flesh quality is due to the presence of specific compounds, the most common of which are geosmin and 2-methylisoborneol. These secondary metabolites, which accumulate in the lipid tissue of fish, are produced by the blue- green algae (cyanobacteria) or by the bacteria of the genus Streptomyces, actinomycetes and myxobacteria. Geosmin gives a clear muddy flavour, while 2-methylisoborneol gives a mildewed taste that can severely affect consumer acceptance and disrupt the marketability of the product. Off-flavour occurs in both earthen ponds and RASs.

Routine management practices

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Below are daily, weekly and monthly activities to perform to ensure that the aquaponic unit is running well. These lists should be made into checklists and recorded. That way, multiple operators always know exactly what to do, and checklists prevent carelessness that can occur with routine activities. These lists are not meant to be exhaustive, but merely a guideline based on the systems described here in this publication and as a review of the management activities.

Safety at work

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Safety is important for both the human operator and the system itself. The most dangerous aspect of aquaponics is the proximity of electricity and water, so proper precautions should be taken. Food safety is important to ensure that no pathogens are transferred to human food. Finally, it is important to take precautions against introducing pathogens to the system from humans.

Electrical safety

Always use a residual-current device (RCD). This is a type of circuit breaker that will cut the power to the system if electricity grounds into the water. The best option is to have an electrician install one at the main electric junction. Alternatively, RCD adaptors are available, and inexpensive, at any hardware or home improvement store. An example of an RCD can be found on most hairdryers. This simple precaution can save lives. Moreover, never hang wires over the fish tanks or filters. Protect cables, sockets and plugs from the elements, especially rain, splashing water and humidity. There are outdoor junction boxes available for these purposes. Check often for exposed wires, frayed cables or faulty equipment, and replace accordingly. Utilize “drip loops” where appropriate to prevent water from running down a wire into the junction.

Securing water levels for a small-scale unit

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One of the most common disasters for small-scale or commercial aquaponic units is a loss-of-water event where all of the water drains from the unit. This can be catastrophic and kill all of the fish, destroying the system. There are several common ways for this to happen, including electricity cuts, blocked pipes, drains left open, forgetting to add new water or disruption of water flow by animals. All of these issues can be fatal for fish in a matter of hours if problems are not dealt with immediately. Below is a list of methods to prevent some of the above situations.

Site selection

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Site selection is an important aspect that must be considered before installing an aquaponic unit. This section generally refers to aquaponic units built outdoors without a greenhouse. However, there are brief comments about greenhouses and shading net structures for larger units. It is important to remember that some of the system’s components, especially the water and stone media, are heavy and hard to move, so it is worth building the system in its final location. Selected sites should be on a surface that is stable and level, in an area that is protected from severe weather but exposed to substantial sunlight.

Sources of aquaponic water

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On average, an aquaponic system uses 1-3 percent of its total water volume per day, depending on the type of plants being grown and the location. Water is used by the plants through natural evapotranspiration as well as being retained within the plant tissues. Additional water is lost from direct evaporation and splashing. As such, the unit will need to be replenished periodically. The water source used will have an impact on the water chemistry of the unit. Below is a description of some common water sources and the common chemical composition of that water. New water sources should always be tested for pH, hardness, salinity, chlorine and for any pollutants in order to ensure the water is safe to use.

Sustainable, local alternatives for aquaponic inputs

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Organic plant fertilizers

Chapter 6 discussed how even balanced aquaponic systems can experience nutrient deficiencies. Although fish food pellets are a whole feed for fish, they do not necessarily have the right quantities of nutrients for plants. Generally, fish feeds have low iron, calcium and potassium values. Plant deficiencies can also arise in suboptimal growing conditions, such as cold weather and winter months. Thus, supplementary plant fertilizers may be necessary, particularly when growing fruiting vegetables or those with high nutrient demands. Synthetic fertilizers are often too harsh for aquaponics and can upset the balanced ecosystem; instead, aquaponics can rely on compost tea for any nutrient supplementation.

System cycling and starting a biofilter colony

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System cycling is a term that describes the initial process of building a bacterial colony when first starting any RAS, including an aquaponic unit. Under normal circumstances, this takes 3-5 weeks; cycling is a slow process that requires patience. Overall, the process involves constantly introducing an ammonia source into the aquaponic unit, feeding the new bacterial colony, and creating a biofilter. The progress is measured by monitoring the nitrogen levels. Generally, cycling takes place once an aquaponic system is built, but it is possible to give the biofilter a head start when creating a new aquaponic system. It is important to understand that during the cycling process there will be high levels of ammonia and nitrite, which could be harmful to fish. Also, make sure all aquaponic components, in particular the biofilter and fish tank, are protected from direct sunlight before starting the process.

The biofilter

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Nitrifying bacteria are vital for the overall functioning of an aquaponic unit. Chapter 4 describes how the biofilter component for each aquaponic method works, and Chapter 5 describes the different bacteria groups that operate in an aquaponic unit. Two major groups of nitrifying bacteria are involved in the nitrification process: 1) the ammonia-oxidizing bacteria (AOB), and 2) the nitrite-oxidizing bacteria (NOB) (Figure 2.6). They metabolize the ammonia in the following order:

The five most important water quality parameters

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Oxygen

Oxygen is essential for all three organisms involved in aquaponics; plants, fish and nitrifying bacteria all need oxygen to live. The DO level describes the amount of molecular oxygen within the water, and it is measured in milligrams per litre. It is the water quality parameter that has the most immediate and drastic effect on aquaponics. Indeed, fish may die within hours when exposed to low DO within the fish tanks. Thus, ensuring adequate DO levels is crucial to aquaponics. Although monitoring DO levels is very important, it can be challenging because accurate DO measuring devices can be very expensive or difficult to find. It is often sufficient for small-scale units to instead rely on frequent monitoring of fish behaviour and plant growth, and ensuring water and air pumps are constantly circulating and aerating the water.

The media bed technique

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Media-filled bed units are the most popular design for small-scale aquaponics. This method is strongly recommended for most developing regions. These designs are efficient with space, have a relatively low initial cost and are suitable for beginners because of their simplicity. In media bed units, the medium is used to support the roots of the plants and also the same medium functions as a filter, both mechanical and biological. This double function is the main reason why media bed units are the simplest; the following sections demonstrate how NFT and DWC methods both require isolated and more complicated components for filtration. However, the media bed technique can become unwieldy and relatively expensive at a larger-scale. Media can become clogged if fish stocking densities exceed the beds’ carrying capacity, and this can require separate filtration. Water evaporation is higher in media beds with more surface area exposed to the sun. Some media are very heavy.

Troubleshooting for common problems in aquaponic systems

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Table 8.4 lists the most common problems when running an aquaponic unit. If anything appears out of the ordinary, immediately check that the water pump and air pumps are functioning. Low DO levels, including accidental leaks, are the number one killer in aquaponic units. As long as the water is flowing, the system is not in an emergency phase and the problem can be addressed systematically and calmly. The first step is always to conduct a full water quality analysis. Understanding the water quality provides feedback essential for determining how to solve any problem.

Unwanted bacteria

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Sulphate reducing bacteria

Nitrifying and mineralizing bacteria are useful to aquaponic systems, but some other types of bacteria are harmful. One of these harmful groups of bacteria is the sulphate- reducing group. These bacteria are found in anaerobic conditions (no oxygen), where they obtain energy through a redox reaction using sulphur. The problem is that this process produces hydrogen sulphide (H₂S), which is extremely toxic to fish. These bacteria are common, found in lakes, saltmarshes and estuaries around the world, and are part of the natural sulphur cycle. These bacteria are responsible for the odour of rotten eggs, and also the grey-black colour of sediments. The problem in aquaponics is when solid wastes accumulate at a faster pace than the heterotrophic bacteria and associated community can effectively process and mineralize them, which can in turn lead to anoxic festering conditions that support these sulphate-reducing bacteria. In high fish density systems, the fish produce so much solid waste that the mechanical filters cannot be cleaned fast enough, which encourages these bacteria to multiply and produce their noxious metabolites. Large aquaponic systems often contain a degassing tank where the hydrogen sulphide can be released safely back to the atmosphere. Degassing is unnecessary in small-scale systems. However, even in small-scale systems, if a foul odor is detected, reminiscent of rotten eggs or raw sewage, it is necessary to take appropriate management action. These bacteria only grow in anoxic conditions, so to prevent them, be sure to supply adequate aeration and increase mechanical filtration to prevent sludge accumulation.

Water quality for fish

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Chapter 2 discussed water quality for aquaponics. Here, the most important water quality parameters are listed again briefly and summarized in Table 7.1.

Nitrogen

Ammonia and nitrite are extremely toxic to fish, and sometimes referred to as “invisible assassins”. Ammonia and nitrite are both considered toxic above levels of 1 mg/litre, although any level of these compounds contributes to fish stress and adverse health effects. There should be close to zero detectable levels of both of these in a seasoned aquaponic system. The biofilter is entirely responsible for transforming these toxic chemicals into a less toxic form. Any detectable levels indicate that the system is unbalanced with an undersized biofilter or that the biofilter is not functioning properly. Ammonia is more toxic in warm basic conditions; if the pH is high, any detectable amount of ammonia is especially dangerous. Water tests for ammonia are called total ammonia nitrogen (TAN), and test for both types of ammonia (ionized and un-ionized). Symptoms of ammonia and nitrite poisoning are often seen as red streaking on the fish body, gills and eyes, scraping on the sides of the tank, gasping at the surface for air, lethargy and death. Nitrate on the other hand is much less toxic to most fish. Most species are able to tolerate levels of more than 400 mg/litre.

Water quality for plants

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Section 3.3 discussed water quality parameters for the aquaponic system as a whole. Here specific considerations for plants are considered and further expanded.

pH

The pH is the most important parameter for plants in an aquaponic system because it influences a plant’s access to nutrients. In general, the tolerance range for most plants is 5.5-7.5. The lower range is below the tolerance for fish and bacteria, and most plants prefer mildly acidic conditions. If the pH goes outside of this range, plants experience nutrient lockout, which means that although the nutrients are present in the water the plants are unable to use them. This is especially true for iron, calcium and magnesium. Sometimes, apparent nutrient deficiencies in plants actually indicate that the pH of the system is outside the optimal range. Figure 6.6 describes the relationship between pH level and the ability for plants to take-up certain nutrients.

Water testing

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In order to maintain good water quality in aquaponic units, it is recommended to perform water tests once per week to make sure all the parameters are within the optimum levels. However, mature and seasoned aquaponic units will have consistent water chemistry and do not need to be tested as often. In these cases water testing is only needed if a problem is suspected. In addition, daily health monitoring of the fish and the plants growing in the unit will indicate if something is wrong, although this method is not a substitution for water testing.

Working within the tolerance range for each organism

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As discussed in Chapter 2, aquaponics is primarily about balancing an ecosystem of three groups of organisms: fish, plants and bacteria (Figure 3.2). Each organism in an aquaponic unit has a specific tolerance range for each parameter of water quality (Table 3.1). The tolerance ranges are relatively similar for all three organisms, but there is need for compromise and therefore some organisms will not be functioning at their optimum level.

1.1 Introduction

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Food production relies on the availability of resources, such as land, freshwater, fossil energy and nutrients (Conijn et al. 2018), and current consumption or degradation of these resources exceeds their global regeneration rate (Van Vuuren et al. 2010). The concept of planetary boundaries (Fig. 1.1) aims to define the environmental limits within which humanity can safely operate with regard to scarce resources (Rockström et al. 2009). Biochemical flow boundaries that limit food supply are more stringent than climate change (Steffen et al. 2015). In addition to nutrient recycling, dietary changes and waste prevention are integrally necessary to transform current production (Conijn et al. 2018; Kahiluoto et al. 2014). Thus, a major global challenge is to shift the growth-based economic model towards a balanced eco-economic paradigm that replaces infinite growth with sustainable development (Manelli 2016). In order to maintain a balanced paradigm, innovative and more ecologically sound cropping systems are required, such that trade-offs between immediate human needs can be balanced whilst maintaining the capacity of the biosphere to provide the required goods and services (Ehrlich and Harte 2015).

1.2 Supply and Demand

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The 2030 Agenda for Sustainable Development emphasizes the need to tackle global challenges, ranging from climate change to poverty, with sustainable food production a high priority (Brandi 2017; UN 2017). As reflected in the UN’s Sustainable Development Goal 2 (UN 2017), one of the greatest challenges facing the world is how to ensure that a growing global population, projected to rise to around 10 billion by 2050, will be able to meet its nutritional needs. To feed an additional two billion people by 2050, food production will need to increase by 50% globally (FAO 2017). Whilst more food will need to be produced, there is a shrinking rural labour force because of increasing urbanization (dos Santos 2016). The global rural population has diminished from 66.4% to 46.1% in the period from 1960 to 2015 (FAO 2017). Whilst, in 2017, urban populations represented more than 54% of the total world population, nearly all future growth of the world’s population will occur in urban areas, such that by 2050, 66% of the global population will live in cities (UN 2014). This increasing urbanization of cities is accompanied by a simultaneously growing network of infrastructure systems, including transportation networks.

1.3 Scientific and Technological Challenges in Aquaponics

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Whilst aquaponics is seen to be one of the key food production technologies which ‘could change our lives’ (van Woensel et al. 2015), in terms of sustainable and efficient food production, aquaponics can be streamlined and become even more efficient. One of the key problems in conventional aquaponics systems is that the nutrients in the effluent produced by fish are different than the optimal nutrient solution for plants. Decoupled aquaponics systems (DAPS), which use water from the fish but do not return the water to the fish after the plants, can improve on traditional designs by introducing mineralization components and sludge bioreactors containing microbes that convert organic matter into bioavailable forms of key minerals, especially phosphorus, magnesium, iron, manganese and sulphur that are deficient in typical fish effluent. Contrary to mineralization components in one-loop systems, the bioreactor effluent in DAPS is only fed to the plant component instead of being diluted in the whole system. Thus, decoupled systems that utilize sludge digesters make it possible to optimize the recycling of organic wastes from fish as nutrients for plant growth (Goddek 2017; Goddek et al. 2018). The wastes in such systems mainly comprise fish sludge (i.e. faeces and uneaten feed that is not in solution) and thus cannot be delivered directly in a hydroponics system. Bioreactors (see Chap. 10) are therefore an important component that can turn otherwise unusable sludge into hydroponic fertilizers or reuse organic wastes such as stems and roots from the plant production component into biogas for heat and electricity generation or DAPS designs that also provide independently controlled water cycling for each unit, thus allowing separation of the systems (RAS, hydroponic and digesters) as required for the control of nutrient flows. Water moves between components in an energy and nutrient conserving loop, so that nutrient loads and flows in each subsystem can be monitored and regulated to better match downstream requirements. For instance, phosphorous (P) is an essential but exhaustible fossil resource that is mined for fertilizer, but world supplies are currently being depleted at an alarming rate. Using digesters in decoupled aquaponics systems allows microbes to convert the phosphorus in fish waste into orthophosphates that can be utilized by plants, with high recovery rates (Goddek et al. 2016, 2018).

1.4 Economic and Social Challenges

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From an economic perspective, there are a number of limitations inherent in aquaponics systems that make specific commercial designs more or less viable (Goddek et al. 2015; Vermeulen and Kamstra 2013). One of the key issues is that stand-alone, independent hydroponics and aquaculture systems are more productive than traditional one-loop aquaponics systems (Graber and Junge 2009), as they do not require trade-offs between the fish and plant components. Traditional, classic single-loop aquaponics requires a compromise between the fish and plant components when attempting to optimize water quality and nutrient levels that inherently differ for the two parts (e.g. desired pH ranges and nutrient requirements and concentrations). In traditional aquaponics systems, savings in fertilizer requirements for plants do not make up for the harvest shortfalls caused by suboptimal conditions in the respective subsystems (Delaide et al. 2016).

1.5 The Future of Aquaponics

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Technology has enabled agricultural productivity to grow exponentially in the last century, thus also supporting significant population growth. However, these changes also potentially undermine the capacity of ecosystems to sustain food production, to maintain freshwater and forest resources and to help regulate climate and air quality (Foley et al. 2005).

One of the most pressing challenges in innovative food production, and thus in aquaponics, is to address regulatory issues constraining the expansion of integrated technologies. A wide range of different agencies have jurisdiction over water, animal health, environmental protection and food safety, and their regulations are in some cases contradictory or are ill-suited for complex integrated systems (Joly et al. 2015). Regulations and legislation are currently one of the most confusing areas for producers and would-be entrepreneurs. Growers and investors need standards and guidelines for obtaining permits, loans and tax exemptions, yet the confusing overlap of responsibilities among regulatory agencies highlights the urgent need for better harmonization and consistent definitions. Regulatory frameworks are frequently confusing, and farm licensing as well as consumer certification remains problematic in many countries. The FAO (in 2015), the WHO (in 2017) and the EU (in 2016) all recently began harmonizing provisions for animal health/well-being and food safety within aquaponics systems and for export-import trade of aquaponic products. For instance, several countries involved in aquaponics are lobbying for explicit wording within the Codex Alimentarius, and a key focus within the EU, determined by the EU sponsored COST Action FA1305, the ‘EU Aquaponics Hub’, is currently on defining aquaponics as a clear and distinct entity. At present, regulations define production for both aquaculture and hydroponics, but have no provisions for merging of the two. This situation often creates excessive bureaucracy for producers who are required to license two separate operations or whose national legislation does not allow for co-culturing (Joly et al. 2015). The EU Aquaponics Hub, which has supported this publication (COST FA1305), defines aquaponics as ‘a production system of aquatic organisms and plants where the majority (> 50%) of nutrients sustaining the optimal plant growth derives from waste originating from feeding the aquatic organisms’ (see Chap. 7).

10.1 Introduction

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The concept of aquaponics is associated with being a sustainable production system, as it re-utilises recirculating aquaculture system (RAS) wastewater enriched in macronutrients (i.e. nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulphur (S)) and micronutrients (i.e. iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B) and molybdenum (Mo)) to fertilise the plants (Graber and Junge 2009; Licamele 2009; Nichols and Savidov 2012; Turcios and Papenbrock 2014). A much debated question is whether this concept can match its own ambition of being a quasi-closed-loop system, as high amounts of the nutrients that enter the system are wasted by discharging the nutrient-rich fish sludge (Endut et al. 2010; Naylor et al. 1999; Neto and Ostrensky 2013). Indeed, to maintain a good water quality in a RAS and aquaponic systems, the water has to be constantly filtrated for solid removal. The two main techniques for solid filtration are to retain the particles in a mesh (i.e. mesh filtration as drum filters) and to allow the particles to decant in clarifiers. In most conventional plants, sludge is recovered out of these mechanical filtration devices and is discharged as sewage. In the best cases, the sludge is dried and applied as fertiliser on land fields (Brod et al. 2017). Notably, up to 50% (in dry matter) of the feed ingested is excreted as solids by fish (Chen et al. 1997), and most of the nutrients that enter aquaponic systems via fish feed accumulate in these solids and so in the sludge (Neto and Ostrensky 2013; Schneider et al. 2005). Hence, effective solid filtration removes, for example, more than 80% of the valuable P (Monsees et al. 2017) that could otherwise be used for plant production. Therefore, recycling these valuable nutrients for aquaponic applications is of major importance. Developing an appropriate sludge treatment able to mineralise the nutrients contained in sludge for re-using them in the hydroponic unit seems to be a necessary process for contributing to close the nutrient loop to a higher degree and thus lowering the environmental impact of aquaponic systems (Goddek et al. 2015; Goddek and Keesman 2018; Goddek and Körner 2019).

10.2 Wastewater Treatment Implementation in Aquaponics

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In aquaponics, the wastewater charged with solids (i.e. the sludge) is a valuable source of nutrients, and appropriate treatments need to be carried out. The treatment goals differ from conventional wastewater treatment because in aquaponics solids and water conservation is of interest. Moreover, regardless of the wastewater treatment applied, its aim should be to reduce solids and at the same time mineralise its nutrients. In other words, the aim is to obtain a solid-free effluent but rich in solubilised nutrients (i.e. anions and cations) that can be reinserted into the water loop in a coupled setup (Fig. 10.1a) or directly into the hydroponic grow beds in a decoupled setup (Fig. 10.1b). Fish sludge solids are mainly composed of degradable organic matter so that the solid reduction can be called organic reduction. Indeed, the complex organic molecules (e.g. proteins, lipids, carbohydrates, etc.) are principally composed of carbon and will be successively reduced to lower molecular weight compounds until the ultimate gaseous forms of COsub2/sub and CHsub4/sub (in the case of anaerobic fermentation). During this degradation process, the macronutrients (i.e. N, P, K, Ca, Mg and S) and micronutrients (i.e. Fe, Mn, Zn, Cu, B and Mo) that were bound to the organic molecules are released into the water in their ionic forms. This phenomenon is called nutrient leaching or nutrient mineralisation. It can be assumed that when high organic reduction is achieved, high nutrient mineralisation would also be achieved. On the one hand, sludge contains a proportion of undissolved minerals, and on the other hand, some macro- and micronutrients are released during the mineralisation process. These can quickly precipitate together and form insoluble minerals. The state between ions and precipitated minerals of most of the macro- and micronutrients is pH dependent. The most well-known minerals that precipitate in bioreactors are calcium phosphate, calcium sulphate, calcium carbonate, pyrite and struvite (Peng et al. 2018; Zhang et al. 2016). Conroy and Couturier (2010) observed that Ca and P were released in anaerobic reactor when the pH dropped under 6. They showed that the release corresponded exactly to the mineralisation of calcium phosphate. Goddek et al. (2018) also observed the solubilisation of P, Ca and other macronutrients in upflow anaerobic sludge blanket reactor (UASB) that turned acidic. Jung and Lovitt (2011) reported a 90% nutrient mobilisation of aquaculture-derived sludge at a very low pH value of 4. In this condition, all the macro- and micronutrients were solubilised. There is thus an antagonism between organic reduction and nutrient mineralisation. Indeed, organic reduction is maximal when the microorganisms are active for degrading the organic compounds, and this happens at pH in a range of 6—8. Because nutrient leaching occurs at pH below 6, for optimal organic reduction and nutrient mineralisation, the most effective would be to divide the process in two steps, i.e. an organic reduction step at pH close to neutral and a nutrient leaching step under acidic conditions. To our knowledge, no operation using this two-step approach has been yet reported. This opens a new field in wastewater treatment and more research for implementation in aquaponics is needed.

10.3 Aerobic Treatments

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Aerobic treatment enhances the oxidation of the sludge by supporting its contact with oxygen. In this case, the oxidation of the organic matter is driven mainly by the respiration of heterotrophic microorganisms. COsub2/sub, the end product of respiration, is released as is shown in Eq. (10.1).

$C_6H_{12}O_6 + 6\ O_2 \rarr 6\ CO_2+6\ H_2O +energy$ (10.1)

This process in aerobic reactors is mainly achieved by injecting air into the sludge—water mixture with air blowers connected to diffusers and propellers. Air injection also ensures a proper mixing of the sludge.

10.4 Anaerobic Treatments

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Anaerobic digestion (AD) has long been used for the stabilisation and reduction of sludge mass process, mainly because of the simplicity of operation, relatively low costs and production of biogas as potential energy source. General stoichiometric representation of anaerobic digestion can be described as follows:

$CnHaOb+(n-a/4-b/2)\cdot H_2O \rarr (n/2-a/8+b/4)\cdot CO_2+(n/2+a/8-b/4)\cdot CH4$ (10.4)

Equation 10.4 Biogas general mass balance (Marchaim 1992).

And the theoretical methane concentration can be calculated as follows:

10.5 Methodology to Quantify the Sludge Reduction and Mineralisation Performance

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To determine the digestion of aquaponic sludge treatment in aerobic and anaerobic bioreactors, a specific methodology needs to be followed. A methodology adapted for aquaponic sludge treatment purposes is presented in this chapter. Specific equations have been developed to precisely quantify their performance (Delaide et al. 2018), and these should be used to evaluate the performance of the treatment applied in a specific aquaponic plant.

In order to evaluate the treatment’s performance, a mass balance approach needs to be achieved. It requires that TSS, COD and nutrient masses are determined for the all reactor inputs (i.e. fresh sludge) and outputs (i.e. effluents). The reactor content also needs to be sampled at the beginning and at the end of the studied period. The input, output and content of the reactors have to be perfectly mixed for sampling. Reactor input and output should basically be sampled every time the reactors are fed with fresh sludge.

10.6 Conclusions

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Fish sludge treatment for reduction and nutrient recovery is in an early phase of implementation. Further research and improvements are needed and will see the day with the increased concern of circular economy. Indeed, fish sludge needs to be considered more as a valuable source instead of a disposable waste.

11.1 Introduction

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In general, mathematical models can take very different forms depending on the system under study, which may range from social, economic and environmental to mechanical and electrical systems. Typically, the internal mechanisms of social, economic or environmental systems are not very well known or understood and often only small data sets are available, while the prior knowledge of mechanical and electrical systems is at a high level, and experiments can easily be done. Apart from this, the model form also strongly depends on the final objective of the modelling procedure. For instance, a model for process design or simulation should contain much more detail than a model used for studying different long-term scenarios.

11.2 Background

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Many definitions of a system are available, ranging from loose descriptions to strict mathematical formulations. In what follows, a system is considered to be an object in which different variables interact at all kinds of time and space scales and that produces observable signals. These types of systems are also called open systems. A graphical representation of a general open system (S) with vector-valued input and output signals is represented in Fig. 11.2. Thus, multiple inputs or outputs are combined in one single arrow. So, the system variables may be scalars or vectors. In addition, they can be continuous or discrete functions of time. It is important to stress that the arrows in Fig. 11.2 represent signal flows and thus not necessarily physical flows.

11.3 RAS Modelling

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Global fish aquaculture reached 50 million tons in 2014 (FAO 2016). Given the growing human population, there is a growing demand for fish proteins. Sustainable growth of aquaculture requires novel (bio)technologies such as recirculating aquaculture systems (RAS). RAS have a low water consumption (Orellana 2014) and allow for a recycling of excretory products (Waller et al. 2015). RAS provide suitable living conditions for fish, as a result of a multistep water treatment, such as particle separation, nitrification (biofiltration), gas exchange and temperature control. Dissolved and particulate excretory products can be transferred to secondary treatment such as plant (Waller et al. 2015) or algae production in integrated aquaagriculture (IAAC) systems. IAAC systems are sustainable alternatives to conventional aquaculture systems and in particular are a promising expansion to RAS. In RAS it would be necessary to circulate the process water which has special implications for the process technology in both, the RAS and the algae/plant system. To combine RAS and algae/plant system, a deep understanding of the interaction between fish and water treatment is prerequisite and can be derived from dynamic modelling. The metabolism in fish follows a daily pattern which is well represented by the gastric evacuation rate (Richie et al. 2004). Particle separation, biofiltration and gas exchange are subjected to the same pattern. For design purposes the characterization of the basic components of a RAS treatment system should be investigated through simulation models. These simulation models are highly complex. Available numerical models for RAS capture only a small part of the complexity and consider only a part of the components with corresponding mechanisms. Hence, in this chapter, only a small part of a dynamic RAS model will be presented, i.e. nitrification-based biofiltration. The conversion of toxic ammonia into nitrate is a central process in the water treatment process in RAS. In the following, the dynamic modelling of the mass balance of ammonia excretion of fish and the conversion of ammonia into nitrate will be demonstrated as well as the transfer of the nutrient into an aquaponic system. With this it is possible not only to engineer a RAS but also to integrate fish production into an IAAC system based on valid parameters.

11.4 Modelling Anaerobic Digestion

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Fig. 11.10 Simulation of TAN (XsubNHx-N,1/sub) in [mg/l] over 2 days = 2880 min with Q = 300 l/min (blue) and Q = 200 l/min (orange)

Fig. 11.11 Simulation of nitrate-N (XsubNO3-N,1/sub) in [mg/l] over 50 days = 72,000 min with QsubExc/sub = 300 l/day (yellow), QsubExc/sub = 480 l/day (orange) and QsubExc/sub = 600 l/day (blue)

Anaerobic digestion (AD) of organic material is a process that involves the sequential steps of hydrolysis, acidogenesis, acetogenesis and methanogenesis (Batstone et al. 2002). The anaerobic digestion of a mixture of proteins, carbohydrates and lipids is visualized in Figure 11.11. Most often, hydrolysis is considered as the rate-limiting step in the anaerobic digestion of complex organic matter (Pavlostathis and GiraldoGomez 1991). Thus, increasing the hydrolysis reaction rate will most likely lead to a higher anaerobic digestion reaction rate. However, increasing the reaction rates needs further understanding of the related process. Further understanding can be obtained via experimentation and/or mathematical modelling. As there are many factors influencing, for instance, the hydrolysis process, such as ammonia concentration; temperature; substrate composition; particle size; pH; intermediates; degree of hydrolysis; i.e. the potential of hydrolysable content; and residence time, it is almost impossible to evaluate the total effect of the factors on the hydrolysis reaction rate through experimentation. Mathematical modelling could therefore be an alternative, but as a result of all the uncertainties in model formulation, rate coefficients and initial conditions, no unique answers can be expected. But, a mathematical modelling framework would allow sensitivity and uncertainty analyses to facilitate the modelling process. As mentioned before, hydrolysis is just one of the steps in anaerobic digestion. Consequently, understanding and optimization of the full anaerobic digestion process needs connections from hydrolysis to the other processes taking place during anaerobic digestion and interactions between all these steps.

11.5 HP Greenhouse Modelling

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The crop water use and nutrient uptake is a central subsystem of aquaponics. The HP part is complex, as pure uptake of water and dissolved nutrients do not simply follow a rather simple linear relationship as, e.g. fish growth. To create a full-functional model, a complete greenhouse simulator is needed. This involves sub-model systems of greenhouse physics including climate controllers and crop biology covering interactive processes with biological and physical stressors.

11.6 Multi-loop Aquaponic Modelling

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Traditional aquaponic designs comprise of aquaculture and hydroponic units involving recirculating water between both subsystems (Körner et al. 2017; Graber and Junge 2009). In such one-loop aquaponic systems, it is necessary to make trade-offs between the conditions of both subsystems in terms of pH, temperature and nutrient concentrations, as fish and plants share one ecosystem (Goddek et al. 2015). By contrast, decoupled double-loop aquaponic systems separate the RAS and hydroponic units from one another, creating detached ecosystems with inherent advantages for both plants and fish. Recently, there has been an increased interest in closing the loop in terms of nutrients as well as increasing the input-output efficiency. For that reason, remineralization (Goddek 2017; Emerenciano et al. 2017; Goddek et al. 2018; Yogev et al. 2016) and desalination loops (Goddek and Keesman 2018) have been incorporated into the overall system design. Such systems are called decoupled multi-loop aquaponic system (Goddek et al. 2016).

11.7 Modelling Tools

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In aquaponics, flow charts or stock and flow diagrams (SFD) and causal loop diagrams (CLDs) are commonly used to illustrate the functionality of the aquaponic system. In the following, flow chart and CLDs will be described.

11.7.1 Flow Charts

To get a systemic understanding of the aquaponics, flow charts with the most important components of the aquaponics are a good tool to show how material flows in the system. This can help, for example, in finding missing components and unbalanced flows and mainly influencing determinants of the subprocesses. Figure 11.18 shows a simple flow chart in aquaponics. In the flow chart, fish food and water are added to the fish tank, where the feed is taken by the fish for growth, the water is enriched with the fish waste and the nutrient-enriched water is added to the hydroponics system to produce plant biomass. From the flow chart, a CLD shown in Fig. 11.19 can be easily constructed.

11.8 Discussion and Conclusions

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Aquaponics are complex technical and biological systems. For example, possible explanations for fish not growing properly can be small food rations, adverse water quality, technical problems causing stress, etc. Due to the inherently slow biology, scientific investigations of the validity of these explanations would be tedious and require several experimental trials to get all important factors and their interactions, demanding a lot of facilities, expertise, research time and financial assets. Therefore, the issue of modelling aquaponic systems was addressed in this chapter. In aquaponics, modelling is required for different objectives: (i) insight/understanding, (ii) analysis, (iii) estimation and (iv) management and control. For all these objectives, appropriate models are required. For example, to achieve objectives (ii) and (iii), an empirical approach can be utilized which uses statistical models to analyse data from previous experimental trials with the objective of extracting as much information as possible without conducting new experiments. Statistical models can reveal the most important factors affecting fish and crop production in the aquaponic systems. Future experiments could concentrate on these factors, thus making the utilization of costly research assets more effective.

12.1 Introduction

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This chapter discusses a number of key allied and alternative technologies that either expand or have the potential to expand the functionality/productivity of aquaponic systems or are associated/stand-alone technologies that can be linked to aquaponics. The creation and development of these systems have at their core the ability, amongst other things, to increase production, reduce waste and energy and in most cases reduce water usage. Unlike aquaponics, which may be seen to be in a mid/teenage stage of development, the novel approaches discussed below are in their infancy. This, however, does not mean that they are not technologies valuable in their own right and have the potential to deliver future food, efficiently and sustainably. The methods discussed below include aeroponics, aeroaquaponics, algaeponics, biofloc technology for aquaponics, maraponics and haloponics and vertical aquaponics.

12.2 Aeroponics

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12.2.1 Background

The US National Aeronautics and Space Administration (NASA) describes aeroponics as the process of growing plants suspended in air without soil or media providing clean, efficient, and rapid food production. NASA furthermore notes that crops can be planted and harvested year-round without interruption, and without contamination from soil, pesticides, and residue and that aeroponic systems also reduce water usage by 98%, fertilizer usage by 60% percent, and eliminate pesticide usage altogether. Plants grown in aeroponic systems have been shown to absorb more minerals and vitamins, making the plants healthier and potentially more nutritious (NASA Spinoff). Other advantages of aeroponics are seen to be that:

12.3 Algaeponics

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12.3.1 Background

Microalgae are unicellular photoautotrophs (ranging from 0.2 μm up to 100 μm) and are classified in various taxonomic groups. Microalgae can be found in most environments but are mostly found in aquatic environments. Phytoplankton are responsible for over 45% of world’s primary production as well as generating over 50% of atmospheric Osub2/sub. In general, there is no major difference in photosynthesis of microalgae and higher plants (Deppeler et al. 2018). However, due to their smaller size and the reduction in a number of internally competitive physiological organelles, microalgae can grow much faster than higher plants (Moheimani et al. 2015). Microalgae can also grow under limited nutrient conditions and have the ability to adapt to a wider range of environmental conditions (Gordon and Polle 2007). Most importantly, microalgal culture does not compete with food crop production regarding arable land and freshwater (Moheimani et al. 2015). Furthermore, microalgae can efficiently utilize inorganic nutrients from waste effluents (Ayre et al. 2017). In general, microalgal biomass contains up to 50% carbon making them a perfect candidate for bioremediating atmospheric COsub2/sub (Moheimani et al. 2012).

12.4 Maraponics and Haloponics

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Although freshwater aquaponics is the most widely described and practiced aquaponic technique, resources of freshwater for food production (agriculture and aquaculture) are becoming increasingly limited and soil salinity is progressively increasing in many parts of the world (Turcios and Papenbrock 2014). This has led to an increased interest and/or move towards alternative water sources (e.g. brackish to highly saline water as well as seawater) and the use of euryhaline or saltwater fish, halophytic plants, seaweed and low salt-tolerant glycophytes (Joesting et al. 2016). It is interesting to note that whilst the amount of saline in underground water is only estimated as 0.93% of world’s total water resources at 12,870,000 kmsup3/sup, this is more than the underground freshwater reserves (10,530,000 kmsup3/sup) which makes up 30.1% of all freshwater reserves (Appelbaum and Kotzen 2016).

12.5 Vertical Aquaponics

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12.5.1 Introduction

Whilst aquaponics can be seen as part of a global solution to increase food production in more sustainable and productive ways and where growing more food in urban areas is now recognized as part of the solution to food security and a global food crisis (Konig et al. 2016), aquaponic systems can themselves become more productive and sustainable by adopting alternative growing technologies and learning from emerging technologies such as vertical farming and living walls (Khandaker and Kotzen 2018). Additionally by being space-efficient, they can be better integrated into urban areas.

12.6 Biofloc Technology (BFT) Applied for Aquaponics

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12.6.1 Introduction

Biofloc technology (BFT) is considered the new ‘blue revolution’ in aquaculture (Stokstad 2010) since nutrients can be continuously recycled and reused in the culture medium, benefited by the in situ microorganism production and by the minimum or zero water exchange (Avnimelech 2015). These approaches might face some serious challenges in the sector such as competition for land and water and the effluents discharged to the environment which contain excess of organic matter, nitrogenous compounds and other toxic metabolites.

12.7 Digeponics

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Anaerobic processing of purposely cultivated biomass, as well as residual plant material from agricultural activity, for biogas production is a well-established method. The bacterially indigestible digestate is returned to the fields as a fertilizer and for building humus. Whilst this process is widespread in agriculture, the application of this technology in horticulture is relatively new. Stoknes et al. (2016) claim that within the ‘Food to waste to food’ (F2W2F) project, an efficient method for the utilization of digestate as substrate and fertilizer has been developed for the first time. The research team coined the term ‘digeponics’ for this circular system. Digeponics, in contrast to aquaponics, replaces the aquaculture part with an anaerobic digester, or, when comparing it to a three loop aquaponic system that includes an anaerobic, the aquaculture part is removed from the system, leaving two main loops, the digestion loop and the horticultural loop.

12.8 Vermiponics and Aquaponics

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It would be remiss in this chapter not to mention earthworms and their introduction into aquaponics, and thus this chapter concludes with a brief résumé of these detritivore invertebrates and their abilities to convert organic waste into fertilizer. It is said that worms and the way that they digest matter were of interest to Aristotle and Charles Darwin as well as the philosophers Pascal and Thoreau (Adhikary 2012) and they were protected by law under Cleopatra. Earthworms are valued in agriculture and horticulture as they are ‘vital to soil health because they transport nutrients and minerals from below to the surface via their waste, and their tunnels aerate the ground’ (National Geographic).

13.1 Introduction

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Aquatic food is recognized to be beneficial to human nutrition and health and will play an essential role in future sustainable healthy diets (Beveridge et al. 2013). In order to achieve this, the global aquaculture sector must contribute to increasing the quantity and quality of fish supplies between now and 2030 (Thilsted et al. 2016). This growth should be promoted not only by increasing the production and/or number of species but also by systems diversification. However, fish from aquaculture has only recently been included in the food security and nutrition (FSN) debate and the future strategies and policies, demonstrating the important role of this production to prevent malnutrition in the future (Bénét et al. 2015), as fish provide a good source of protein and unsaturated fats, as well as minerals and vitamins. It is important to note that many African nations are promoting aquaculture as the answer to some of their current and future food production challenges. Even in Europe, fish supply is currently not self-sufficient (with an unbalanced domestic supply/demand), being increasingly dependent on imports. Therefore, ensuring the successful and sustainable development of global aquaculture is an imperative agenda for the global and European economy (Kobayashi et al. 2015). Sustainability is generally required to show three key aspects: environmental acceptability, social equitability and economic viability. Aquaponic systems provide an opportunity to be sustainable, by combining both animal and plant production systems in a cost-efficient, environmentally friendly and socially beneficial ways. For Staples and Funge-Smith (2009), sustainable development is the balance between ecological well-being and human well-being, and in the case of aquaculture, an ecosystem approach has been only recently understood as a priority area for research.

13.2 Sustainable Development of Fish Nutrition

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The sustainable development of fish nutrition in aquaculture will need to correspond with the challenges that aquaponics delivers with respect to the growing need for producing high-quality food. Manipulating the nitrogen, phosphorus and the mineral content of fish diets used in aquaponics is one way of influencing the rates of the accumulation of nutrients, thereby reducing the need for the artificial and external supplementation of nutrients. According to Rakocy et al. (2004), fish and feed waste provide most of the nutrients required by plants if the optimum ratio between daily fish feed input and plant growing areas is sustained. Solid fish waste called ‘sludge’ in aquaponic systems results in losing approximately half of the available input nutrients, especially phosphorus, that theoretically could be used for plant biomass production but information is still limited (Delaide et al. 2017; Goddek et al. 2018). Whilst the goal of sustainability in fish nutrition in aquaculture will in the future be achieved by using tailor-made diets, fish feed in aquaponics needs to fulfil the nutritional requirements both for fish and for plants. Increases in sustainability will in part derive from less dependence on fishmeal (FM) and fish oil (FO) and novel, high-energy, low-carbon footprint raw natural ingredients. To safeguard biodiversity and the sustainable use of natural resources, the use of wild fisheries-based FM and FO needs to be limited in aquafeeds (Tacon and Metian 2015). However, fish performance, health and final product quality may be altered when substituting dietary FM with alternative ingredients. Thus, fish nutrition research is focused on the efficient use and transformation of the dietary components to provide the necessary essential nutrients that will maximize growth performance and achieve sustainable and resilient aquaculture. Replacing FM, which is an excellent but costly protein source in fish diets, is not straightforward due to its unique amino acid profile, high nutrient digestibility, high palatability, adequate amounts of micronutrients, as well as having a general lack of anti-nutritional factors (Gatlin et al. 2007).

13.3 Feed Ingredients and Additives

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13.3.1 Protein and Lipid Sources for Aquafeeds

Since the end of the twentieth century, there have been significant changes in the composition of aquafeeds but also advances in manufacturing. These transformations have originated from the need to improve the economic profitability of aquaculture as well as to mitigate its environmental impacts. However, the driving forces behind these changes is the need to decrease the amount of fishmeal (FM) and fish oil (FO) in the feeds, which have traditionally constituted the largest proportion of the feeds, especially for carnivorous fish and shrimp. Partly because of overfishing but especially due to the continuous increase in global aquaculture volume, there is an increasing need for alternative proteins and oils to replace FM and FO in aquafeeds.

13.4 Physiological Rhythms: Matching Fish and Plant Nutrition

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The design of feeds for fish is crucial in aquaponics because fish feed is the single or at least the main input of nutrients for both animals (macronutrients) and plants (minerals) (Fig. 13.3).

Nitrogen is introduced to the aquaponic system through protein in fish feed which is metabolized by fish and excreted in the form of ammonia. The integration of recirculating aquaculture with hydroponics can reduce the discharge of unwanted nutrients to the environment as well as generate profits. In an early economic study, phosphorus removal in an integrated trout and lettuce/basil aquaponic system proved to be cost-saving (Adler et al. 2000). Integrating fish feeding rates is also paramount to fulfil the nutritional requirements of plants. Actually, farmers need to know the amount of feed used in the aquaculture unit to calculate how much nutrient needs to be supplemented to promote plant growth in the hydroponic unit. For instance, in a tilapia-strawberry aquaponic system, the total amount of feed required to produce ions (e.g. NOsub3/subsup—,/sup Casub2/subsup+/sup, Hsub2/subPOsub4/subsup—/sup and Ksup+/sup) for plants was calculated at different fish densities, with better result for small fish density 2 kg fish/msup-3/sup to reduce the cost of hydroponic solution supplementation (Villarroel et al. 2011).

14.1 Introduction

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Nowadays, aquaponic systems are the core of numerous research efforts which aim at better understanding these systems and at responding to new challenges of food production sustainability (Goddek et al. 2015; Villarroel et al. 2016). The cumulated number of publications mentioning “aquaponics” or derived terms in the title went from 12 in early 2008 to 215 in 2018 (January 2018 Scopus database research results). In spite of this increasing number of papers and the large area of study topics they are covering, one critical point is still missing, namely plant pest management (Stouvenakers et al. 2017). According to a survey on EU Aquaponic Hub members, only 40% of practitioners have some notions about pests and plant pest control (Villarroel et al. 2016).

14.2 Microorganisms in Aquaponics

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Microorganisms are present in the entire aquaponics system and play a key role in the system. They are consequently found in the fish, the filtration (mechanical and biological) and the crop parts. Commonly, the characterisation of microbiota (i.e. microorganisms of a particular environment) is carried out on circulating water, periphyton, plants (rhizosphere, phyllosphere and fruit surface), biofilter, fish feed, fish gut and fish faeces. Up until now, in aquaponics, most of microbial research has focused on nitrifying bacteria (Schmautz et al. 2017). Thus, the trend at present is to characterise microorganisms in all compartments of the system using modern sequencing technologies. Schmautz et al. (2017) identified the microbial composition in different parts of the system, whereas Munguia-Fragozo et al. (2015) give perspectives on how to characterize aquaponics microbiota from a taxonomical and functional point of view by using cutting-edge technologies. In the following sub-sections, focus will be only brought on microorganisms interacting with plants in aquaponic systems organised into plant beneficial and plant pathogenic microorganisms.

14.3 Protecting Plants from Pathogens in Aquaponics

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At the moment aquaponic practitioners operating a coupled system are relatively helpless against plant diseases when they occur, especially in the case of root pathogens. No pesticide nor biopesticide is specifically developed for aquaponic use (Rakocy 2007; Rakocy 2012; Somerville et al. 2014; Bittsanszky et al. 2015; Sirakov et al. 2016). In brief, curative methods are still lacking. Only Somerville et al. (2014) list the inorganic compounds that may be used against fungi in aquaponics. In any case, an appropriate diagnostic of the pathogen(s) causing the disease is mandatory in order to identify the target(s) for curative measures. This diagnosis requires good expertise in terms of observation capacity, plant pathogen cycle understanding and analysis of the situation. However, in case of generalist (not specific) symptoms and depending on the degree of accuracy needed, it is often necessary to use laboratory techniques to validate the hypothesis with respect to the causal agent (Lepoivre 2003). Postma et al. (2008) reviewed the different methods to detect plant pathogens in hydroponics, and four groups were identified:

14.4 The Role of Organic Matter in Biocontrol Activity in Aquaponic Systems

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In Sect. 14.2.3, the suppressiveness of aquaponic systems was suggested. As stated before, the main hypothesis is related to the water recirculation as it is for hydroponic systems. However, a second hypothesis exists and this is linked to the presence of organic matter in the system. Organic matter that could drive a more balanced microbial ecosystem including antagonistic agents which is less suitable for plant pathogens (Rakocy 2012).

In aquaponics, organic matter comes from water supply, uneaten feeds, fish faeces, organic plant substrate, microbial activity, root exudates and plant residues (Waechter-Kristensen et al. 1997; Naylor et al. 1999; Waechter-Kristensen et al. 1999). In such a system, heterotrophic bacteria are organisms able to use organic matter as a carbon and energy source, generally in the form of carbohydrates, amino acids, peptides or lipids (Sharrer et al. 2005; Willey et al. 2008; Whipps 2001). In recirculated aquaculture (RAS), they are mainly localised in the biofilter and consume organic particles trapped in it (Leonard et al. 2000; Leonard et al. 2002). However, another source of organic carbon for heterotrophic bacteria is humic substances present as dissolved organic matter and responsible for the yellow-brownish coloration of the water (Takeda and Kiyono 1990 cited by Leonard et al. 2002; Hirayama et al. 1988). In the soil as well as in hydroponics, humic acids are known to stimulate plant growth and sustain the plant under abiotic stress conditions (Bohme 1999; du Jardin 2015). Proteins in the water can be used by plants as an alternative nitrogen source thus enhancing their growth and pathogen resistance (Adamczyk et al. 2010). In the recirculated water, the abundance of free-living heterotrophic bacteria is correlated with the amount of biologically available organic carbon and carbon-nitrogen ratio (C/N) (Leonard et al. 2000; Leonard et al. 2002; Michaud et al. 2006; Attramadal et al. 2012). In the biofilter, an increase in the C/N ratio increases the abundance of heterotrophic bacteria at the expense of the number of autotrophic bacteria responsible for the nitrification process (Michaud et al. 2006; Michaud et al. 2014). As implied, heterotrophic microorganisms can have a negative impact on the system because they compete with autotrophic bacteria (e.g. nitrifying bacteria) for space and oxygen. Some of them are plant or fish pathogens, or responsible for off-flavour in fish (Chang-Ho 1970; Funck-Jensen and Hockenhull 1983; Jones et al. 1991; Leonard et al. 2002; Nogueira et al. 2002; Michaud et al. 2006; Mukerji 2006; Whipps 2001; Rurangwa and Verdegem 2015). However, heterotrophic microorganisms involved in the system can also be positive (Whipps 2001; Mukerji 2006). Several studies using organic fertilizers or organic soilless media, in hydroponics, have shown interesting effects where the resident microbiota were able to control plant diseases (Montagne et al. 2015). All organic substrates have their own physico-chemical properties. Consequently, the characteristics of the media will influence microbial richness and functions. The choice of a specific plant media could therefore influence the microbial development so as to have a suppressive effect on pathogens (Montagne et al. 2015; Grunert et al. 2016; Montagne et al. 2017). Another possibility of pathogen suppression related to organic carbon is the use of organic amendments in hydroponics (Maher et al. 2008; Vallance et al. 2010). By adding composts in soilless media like it is common use in soil, suppressive effects are expected (Maher et al. 2008). Enhancing or maintaining a specific microorganism such as Pseudomonas population by adding some formulated carbon sources (e.g. nitrapyrin-based product) as reported by Pagliaccia et al. (2007) and Pagliaccia et al. (2008) is another possibility. The emergence of organic soilless culture also highlights the involvement of beneficial microorganisms against plant pathogens supported by the use of organic fertilizers. Fujiwara et al. (2013), Chinta et al. (2014), and Chinta et al. (2015) reported that fertilization with corn steep liquor helps to control Fusarium oxysporum f.sp. lactucae and Botrytis cinerea on lettuces and Fusarium oxysporum f.sp. radicis-lycopersici on tomato plants. And even if hardly advised for aquaponic use, 1 g/L of fish-based soluble fertilizer (Shinohara et al. 2011) suppresses bacterial wilt on tomato caused by Ralstonia solanacearum in hydroponics (Fujiwara et al. 2012).

14.5 Conclusions and Future Considerations

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This chapter aimed to give a first report of plant pathogens occurring in aquaponics, reviewing actual methods and future possibilities to control them. Each strategy has advantages and disadvantages and must be thoroughly designed to fit each case. However, at this time, curative methods in coupled aquaponic systems are still limited and new perspectives of control must be found. Fortunately, suppressiveness in terms of aquaponic systems could be considered, as already observed in hydroponics (e.g. in plant media, water, and slow filters). In addition, the presence of organic matter in the system is an encouraging factor when compared to soilless culture systems making use of organic fertilisers, organic plant media or organic amendments.

15.1 Introduction

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Switching towards a fully sustainable energy system will partly require switching from a centralised generation and distribution system, towards a decentralised system, due to the rise of decentralised energy generation technologies using wind and rooftop solar radiation. In addition, integrating the heat and transport sectors into the electricity system will lead to a very significant increase in peak demand. These developments require massive and costly adaptations to the energy infrastructure, while the utilisation of existing production assets is expected to drop from 55% to 35% by 2035 (Strbac et al. 2015). This poses a major challenge, but also an opportunity: if the energy flows can be balanced locally in microgrids, the demand for expensive infrastructure upgrade can be minimised, while providing extra stability to the main grid. For these reasons, ‘microgrids have been identified as a key component of the Smart Grid for improving power reliability and quality, increasing system energy efficiency’ (Strbac et al. 2015).

15.2 The Smarthoods Concept

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To unlock the full potential of the Food—Water—Energy nexus with respect to decentralised microgrids, a fully integrated approach focuses not only on energy (microgrid) and food (aquaponics) but also on utilising the local water cycle. The integration of various water systems (such as rainwater collection, storage and wastewater treatment) within aquaponic-integrated microgrids yields the biggest potential for efficiency, resilience and circularity. The concept of a fully integrated and decentralised Food—Water—Energy microgrid will from now on be referred to as a Smarthood (smart neighbourhood) and is depicted in Fig. 15.2.

15.3 Goal

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The goal of this research is to quantify the degree of self-sufficiency and flexibility for a microgrid integrated with a decoupled multi-loop aquaponics system.

15.4 Method

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A neighbourhood of 50 households was assumed a ‘Smarthood’, with a decoupled multi-loop aquaponics facility present that is capable of providing fish and vegetables for all the 100 inhabitants of the Smarthood.

For the detailed modelling of the Smarthood, a hypothetical reference case of a suburban neighbourhood in Amsterdam was used, consisting of 50 households (houses) with an average household occupancy of 2 persons per household (100 persons total). In addition, one urban aquaponic facility consists of a greenhouse, aquaculture system, a UASB and a distillation unit. The dimensioning of the different components is motivated using data for a typical Dutch household and greenhouse (see Table 15.1).

15.5 Results

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The total electrical and thermal consumption of both the houses and the aquaponic greenhouse facility (modelled from the data in Tables 15.1 and 15.2) is shown in Table 15.3. The aquaponic greenhouse facility is responsible for 38.3% of power consumption and 51.4% of heat consumption. The power demand for an aquaponics facility integrated in a residential microgrid is therefore slightly over one-third of the total local energy demand, given that all of the residential energy and vegetable/fish production is done locally. The heat demand comprises roughly 50% of the total heat demand, which can be attributed for a large part to the distillation unit running on high-temperature water.

15.6 Discussion

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Self-Sufficiency The energy system proposed for the Smarthood concept is capable of achieving near full grid-independence through the use of the flexibility provided by the various system components. The aquaponic system, especially, has a positive

Table 15.4 Flexible demand of the aquaponic system

table thead tr class=“header” th Component /th th Order of magnitude /th th Flexibility /th /tr /thead tbody tr class=“odd” td rowspan=3 Pumps /td td 0.05–0.15 kWsube/sub Msup3/sup /td td rowspan=3 Not all pumps have to run continuously. Main processes (oxygen control, ammonia control, COsub2/sub control, tank exchanges, suspended solids control) must run continuously. Smaller processes such as pH buffer dosing, backwash routines, water exchanges or back-up oxygenation do not have to run continuously /td /tr tr class=“even” td 1–3 kWsube/sub /td /tr tr class=“even” td 8,76–28,26 MWhsube/sub/year /td /tr tr class=“odd” td rowspan=2 Lighting /td td 80–150 W/msup2/sup /td td rowspan=2 Plants need ~4–6 h of darkness, the rest of the day they can be lit artificially. This leaves approx. 0 (summer) to 12 (winter) hours of flexible additional lighting /td /tr tr class=“even” td With a capacity factor of 10–20% this leads to 28–105 MWhsube/sub/year kWsube/sub /td /tr tr class=“odd” td rowspan=2 Space heating (underfloor) and aquaculture tank heating /td td 444 kWsubth/sub/msup2/sup/year /td td rowspan=2 Due to the high thermal mass of the concrete floor and the large water volume in the RAS tank, the heat load is extremely flexible /td /tr tr class=“odd” td 177,8 MWhsubth/sub/year /td /tr tr class=“even” td rowspan=2 Distillation unit /td td 50 kWsubth/sub MWhsube/sub/year /td td rowspan=2 The distillation unit operates on hot water (70–90 ˚C) and can be operated with a significant degree of flexibility (MemSys 2017) /td /tr tr class=“odd” td 166,4 MWhsubth/sub/year /td /tr /tbody /table

15.7 Conclusions

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The goal of this research was to quantify the degree of flexibility and self-sufficiency that an aquaponics integrated microgrid can provide. In order to attain this answer, a neighbourhood of 50 households was assumed a ‘Smarthood’, with a decoupled multi-loop aquaponics facility present that is capable of providing fish and vegetables for all the 100 inhabitants of the Smarthood.

The results are promising: thanks to the high degree of flexibility inherent in the aquaponic system as a result of high thermal mass, flexible pumps and adaptive lighting, the overall degree of self-sufficiency is 95.38%, making it nearly completely self-sufficient and grid independent. With the aquaponics system being responsible for 38.3% of power consumption and 51.4% of heat consumption, the impact of the aquaponics facility on the total system’s energy balance is very high.

16.1 Introduction

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Key drivers stated for aquaponic research are the global environmental, social and economic challenges identified by supranational authorities like the Food and Agriculture Organization (FAO) of the United Nations (UN) (DESA 2015) whose calls for sustainable and stable food production advance the ’need for new and improved solutions for food production and consumption’ (1) (Junge et al. 2017; Konig et al. 2016). There is growing recognition that current agricultural modes of production cause wasteful overconsumption of environmental resources, rely on increasingly scarce and expensive fossil fuel, exacerbate environmental contamination and ultimately contribute to climate change (Pearson 2007). In our time of ‘peak-everything’ (Cohen 2012), ‘business as usual’ for our food system appears at odds with a sustainable and just future of food provision (Fischer et al. 2007). A food system revolution is urgently needed (Kiers et al. 2008; Foley et al. 2011), and as the opening chapters (Chaps. 1 and 2) of this book attest, aquaponics technology shows much promise. The enclosed systems of aquaponics offer an especially alluring convergence of potential resolutions that could contribute towards a more sustainable future (Kőmíves and Ranka 2015). But, we ask, what kind of sustainable future might aquaponics research and aquaponics technology contribute towards? In this chapter, we take a step back to consider the ambitions of our research and the functions of our technology.

16.2 The Anthropocene and Agriscience

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‘Today, humankind has begun to match and even exceed some of the great forces of nature […] [T]he Earth System is now in a no analogue situation, best referred to as a new era in the geological history, the Anthropocene’ (Oldfield et al. 2004: 81).

The scientific proposal that the Earth has entered a new epoch—-’the Anthropocene’—-as a result of human activities was put forward at the turn of the new millennium by the chemist and Nobel Laureate Paul Crutzen and biologist Eugene Stoermer (Crutzen and Stoermer 2000a). Increasing quantitative evidence suggests that anthropogenic material flows stemming from fossil fuel combustion, agricultural production and mineral extraction now rival in scale those natural flows supposedly occurring outside of human activity (Steffen et al. 2015a). This is a moment marked by unprecedented and unpredictable climatic, environmental and ecological events (Williams and Jackson 2007). The benign era of the Holocene has passed, so the proposal claims; we have now entered a much more unpredictable and dangerous time where humanity recognises its devastating capacity to destabilise planetary processes upon which it depends (Rockström et al. 2009, Steffen et al. 2015b; See chapter 1). The Anthropocene is therefore a moment of realisation, where the extent of human activities must be reconciled within the boundaries of biophysical processes that define the safe operating space of a stable and resilient Earth system (Steffen et al. 2015b).

16.3 Getting Beyond the Green Revolution

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The Anthropocene marks a step change in the relation between humans and our planet. It demands a rethink of the current modes of production that currently propel us on unsustainable trajectories. Until now, such reflexive commitments have not been required of agriscience research and development. It is worth remembering that the Green Revolution, in both its ambitions and methods, was for some time uncontroversial; agriculture was to be intensified and productivity per unit of land or labour increased (Struik 2006). Without doubt, this project, whose technological innovations were vigorously promoted by governments, companies and foundations around the world (Evenson and Gollin 2003), was phenomenally successful across vast scales. More calories produced with less average labour time in the commodity system was the equation that allowed the cheapest food in world history to be produced (Moore 2015). In order to simplify, standardise and mechanise agriculture towards increases in productivity per worker, plant and animal, a series of biophysical barriers had to be overridden. The Green Revolution achieved this largely through non-renewable inputs.

16.4 Paradigm Shift for a New Food System

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To claim that Agriculture is ‘at a crossroads’ (Kiers et al. 2008) does not quite do justice to the magnitude of the situation. The gaping ‘sustainability gap’ (Fischer et al. 2007) amidst unanimous calls for sustainability are increasingly being met with common response amongst researchers: pleas for revolutionary measures and paradigm shifts. Foley et al. (2011: 5) put it quite directly: ‘The challenges facing agriculture today are unlike anything we have experienced before, and they require revolutionary approaches to solving food production and sustainability problems. In short, new agricultural systems must deliver more human value, to those who need it most, with the least environmental harm’. Somehow, world agriculture’s current role as the single largest driver of global environmental change must shift into a ‘critical agent of a world transition’ towards global sustainability within the biophysical safe operating space of the Earth (Rockström et al. 2017).

16.5 Aquaponic Potential or Misplaced Hope?

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Contemporary aquaponic research has shown keen awareness of particular concerns raised in the Anthropocene problematic. Justifications for aquaponic research have tended to foreground the challenge of food security on a globe with an increasing human population and ever strained resource base. For instance, König et al. (2016) precisely situate aquaponics within the planetary concerns of Anthropocene discourse when they state: ‘Assuring food security in the twenty-first century within sustainable planetary boundaries requires a multi-faceted agro-ecological intensification of food production and the decoupling from unsustainable resource use’. Towards these important sustainability goals, it is claimed that aquaponic technology shows much promise (Goddek et al. 2015). The innovative enclosed systems of aquaponics offer an especially alluring convergence of potential resolutions that could contribute towards a more sustainable future.

16.6 Towards a 'Sustainability First' Paradigm

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As we saw earlier, it has been stressed that the goal to move towards sustainable intensification grows from the acknowledgment of the limits of the conventional agricultural development paradigm and its systems of innovation. Acknowledging the need for food system innovations that exceed the traditional paradigm and that can account for the complexity arising from sustainability and food security issues, Fischer et al. (2007) have called for no less than ‘a new model of sustainability’ altogether. Similarly, in their recent plea for global efforts towards sustainable intensification, Rockström et al. (2017) have pointed out that a paradigm shift in our food system entails challenging the dominant research and development patterns that maintain the ‘productivity first’ focus whilst subordinating sustainability agendas to a secondary, ‘mitigating’ role. Instead, they call for a reversal of this paradigm so that ‘sustainable principles become the entry point for generating productivity enhancements’. Following this, we suggest a sustainability first vision for aquaponics as one possible orientation that can both offer coherence to the field and guide its development towards the proclaimed goals of sustainability and food security.

16.7 'Critical Sustainability Knowledge' for Aquaponics

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16.7.1 Partiality

Despite contemporary accounts of sustainability that underline its complex, multidimensional and contested character, in practice, much of the science that engages with sustainability issues remains fixed to traditional, disciplinary perspectives and actions (Miller et al. 2014). Disciplinary knowledge, it must be said, has obvious value and has delivered huge advances in understanding since antiquity. Nevertheless, the appreciation and application of sustainability issues through traditional disciplinary channels has been characterised by the historic failure to facilitate the deeper societal change needed for issues such as the one we contend with here—-the sustainable transformation of the food system paradigm (Fischer et al. 2007).

16.8 Conclusion: Aquaponic Research into the Anthropocene

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The social—biophysical pressures of and on our food system converge in the Anthropocene towards what becomes seen as an unprecedented task for the global community, requiring ’nothing less than a planetary food revolution’ (Rockström et al. 2017). The Anthropocene requires food production innovations that exceed traditional paradigms, whilst at the same time are able to acknowledge the complexity arising from the sustainability and food security issues that mark our times. Aquaponics is one technological innovation that promises to contribute much towards these imperatives. But this emergent field is in an early stage that is characterised by limited resources, market uncertainty, institutional resistance and high risks of failure—-an innovation environment where hype prevails over demonstrated outcomes. The aquaponics research community potentially holds an important place in the development path of this technology. As an aquaponics research community, we need to craft viable visions for the future.

17.1 Introduction

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The European Food Safety Authority reported a variety of drivers and potential issues associated with new trends in food production, and aquaponics was identified as a new food production process/practice (Afonso et al. 2017). As a new food production process, aquaponics can be defined as ’the combination of animal aquaculture and plant culture, through a microbial link and in a symbiotic relationship’. In aquaponics, the basic approach is to get benefit from the complementary functions of the organisms and nutrient recovery. The aquaculture part of the system applies principles that are similar to recirculating aquaculture systems (RAS). Aquaponics has gained momentum due to its superior features compared to traditional production systems. Thus, aquaponics seems capable of maintaining ecosystems and strengthening capacity for adaptation to climate change, extreme weather, drought, flooding and other disasters. These attributes are within reach, but as in other agri-/aquacultural production, aquaponics is not free of risks. Given the complexity of aquaponics as an environment for co-production of aquatic animals with plants, the hazards and risks may be more complicated.

17.2 Aquaponics and Risk: A Development Perspective for Fish Health

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Fish pathogens are prevalent in the aquatic environment, and fish are generally able to resist them unless overloaded by the allostatic load (Yavuzcan Yıldız and Seçer 2017). Allostasis refers to the ‘stability through change’ proposed by Sterling and Eyer (1988). Put simply this is the effort of fish to maintain homeostasis through changes in physiology. Allostatic load of fish in aquaponics may be a challenging factor as aquaponics is a complex system mainly in terms of the water quality and the microbial community in the system. Hence, the diseases of fish are generally speciesand system-specific. Specific aquaponic diseases have not been described yet. From aquaculture, it is known that fish diseases are difficult to detect and are usually the end result of the interaction between various factors involving the environment, nutritional status of the fish, the immune robustness of the fish, existence of an infectious agent and/or poor husbandry and management practices. In order to sustain aquaponic systems, an aquatic health management approach needs to be developed considering the species cultured, the complexity of environments in aquaponics and the type of the aquaponic system management. Profitability in aquaponic production can be affected by even small percentage decreases in production, as seen in aquaculture (Subasinghe 2005).

17.3 Hazard Identification

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In risk analysis, a hazard is generally specified by describing what might go wrong and how this might happen (Ahl et al. 1993). A hazard refers not only to the magnitude of an adverse effect but also to the likelihood of the adverse effect occurring (Müller-Graf et al. 2012). Hazard identification is important for revealing the factors that may favour the establishment of a disease and/or potential pathogen threat, or otherwise detrimental for fish welfare. Biological pathogens are recognised as hazard in aquaculture by Bondad-Reantaso et al. (2008). A broad range of factors can be taken into consideration as long as they are associated with disease occurrence, i.e. they are hazards.

17.4 Fish Health Management

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17.4.1 Fish Diseases and Prevention

While fish diseases caused by bacteria, viruses, parasites or fungi can have a significant negative impact on aquaculture (Kabata 1985), the appearance of a disease in aquaponic systems can be even more devastating. Maintenance of fish health in aquaponic systems is more difficult than in RAS, and, in fact, control of fish diseases is one of the main challenges for successful aquaponics (Sirakov et al. 2016). Diseases which affect fish can be divided into two categories: infectious and non-infectious fish diseases. Infectious diseases are caused by different microbial pathogens transmitted either from the environment or from other fish. Pathogens can be transmitted between the fish (horizontal transmission) or vertically, by (externally or internally) infected eggs or infected milt. More than half of the infectious disease outbreaks in aquaculture (54.9%) are caused by bacteria, followed by viruses, parasites and fungi (McLoughlin and Graham 2007). Often, although clinical signs or lesions are not present, fish can carry pathogens in a subclinical or carrier state (Winton 2002). Fish diseases can be caused by ubiquitous bacteria, present in any water containing organic enrichment. Under certain conditions, bacteria quickly become opportunistic pathogens. The presence of low numbers of parasites on the gills or skin usually does not lead to significant health problems. The capability of a pathogen to cause clinical disease depends on the interrelationship of six major components related to fish and the environment in which they live (physiological status, host, husbandry, environment, nutrition and pathogen). If any of the components is weak, it will affect the health status of the fish (Plumb and Hanson 2011). Non-infectious diseases are usually related to environmental factors, inadequate nutrition or genetic defects (Parker 2012). Successful fish health management is accomplished through disease prevention, reduction of infectious disease incidence and reduction of disease severity when it occurs. Avoidance of contact between the susceptible fish and a pathogen should be a critical goal, in order to prevent outbreak of infectious disease.

17.5 Treatment Strategies in Aquaponics

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Treatment options for diseased fish in an aquaponic system are very limited. As both fish and plants share the same water loop, medications used for disease treatments can easily harm or destroy the plants, and some may get absorbed by the plants, causing withdrawal periods or even making them unusable for consumption. The medications can also have detrimental effects on the beneficial bacteria in the system. If a medicinal treatment is absolutely necessary, it must be implemented early in the course of the disease. The diseased fish is transferred into a separate (hospital, quarantine) tank isolated from the system for treatment. When returning the fish after the treatment, it is important not to transfer the used medications into the aquaponic system. All these limitations require improvements of disease management options with minimal negative effects to the fish, the plants and the system (Goddek et al. 2015, 2016; Somerville et al. 2014; Yavuzcan Yildiz et al. 2017). One of the most used and effective, old-school treatments against the most common bacterial, fungal and parasitic infections in fish is a salt (sodium chloride) bath. Salt is beneficial for the fish, but can be detrimental to the plants in the system (Rakocy 2012), and the whole treatment procedure must be performed in a separate tank. A good option is to separate the recirculating aquaculture unit from the hydroponic unit (decoupled aquaponic systems) (see Chap. 8). Decoupling allows for fish disease and water treatment options that are not possible in coupled systems (Monsees et al. 2017) (see Chap. 7). One recent improvement for the control of fish ectoparasites and disinfection in the aquaponic systems is the use of Wofasteril (KeslaPharmaWolfen GMBH, Bitterfeld-Wolfen, Germany), a peracetic acid-containing product that leaves no residues in the system (Sirakov et al. 2016). Alternatively, hydrogen peroxide can be used, but at a much higher concentration. While these chemicals have minimal side effects, their presence is undesirable in aquaponic systems and alternative approaches, such as biological control methods, are required (Rakocy 2012).

18.1 Introduction: Beyond Myths

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Although we have witnessed the first research developments in aquaponics as far back as the late 1970s (Naegel 1977; Lewis et al. 1978), there is still a long road ahead for the sound economical assessment of aquaponics. The industry is developing slowly, and thus available data is often based on model cases from research and not on commercial-based systems. After initial positive conclusions about the economic potentials of aquaponics in research-based settings of the low-investment systems in USA, primarily the system in Virgin Islands (Bailey et al. 1997) and Alberta(SavidovandBrooks 2004),commercial aquaponicsencountered ahigh level of early enthusiasm in business contexts, often based on unrealistic expectations.

18.2 Hypothetical Modelling, Small-Scale Case Studies and Surveys Amongst Farmers

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Early research on commercial aquaponics focused on evaluation and the development of specific, mostly research institute-led case studies. These first results were highly positive and optimistic about the future of commercial aquaponics. Bailey et al. (1997) concluded that, at least in the case of Virgin Islands, aquaponic farms can be profitable. Savidov and Brooks (2004) reported that the yields of cucumbers and tomatoes calculated on an annual basis exceeded the average values for commercial greenhouse production based on conventional hydroponics technology in Alberta. Adler et al. (2000) performed an economic analysis of a 20-year expected scenario of producing lettuce and rainbow trout and argued that the integration of the fish and plant production systems produces economic costs savings over either system alone. They concluded that an approx. $300.000 investment would have a 7.5-year payback period.

18.3 Hypothetical Modelling Data from Europe

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In Hawaii, Baker (2010) calculated the break-even price of aquaponics lettuce and Tilapia production based on a hypothetical operation. The study estimates that the break-even price of lettuce is $3.30/kg and tilapia is $11.01/kg. Although his conclusion is that this break-even can potentially be economically viable for Hawaii, such break-even prices are much too high for most European contexts, especially when marketing through retailers and conventional distribution channels. In the Philippines, Bosma (2016) concluded that aquaponics can only be financially sustainable if the producers manage to secure high-end niche markets for fish and large markets for fresh organic vegetables.

18.4 Aquaponic Farms in Europe

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Thorarinsdottir (2015) identified ten pilot aquaponic units in Europe, approximately half of which were at the stage of setting up still rather small-scale systems for commercial production. Villarroel et al. (2016) estimated that the number of aquaponic commercial enterprises in Europe comprised approximately 20 companies. Currently, Villarroel (2017) identifies 52 research organisations (universities, vocational schools, research institutes) and 45 commercial enterprises in Europe. Only a handful of these, however, sell aquaponic produce and could be considered as an aquaponic farm. In 2016, as a spin-off from the COST FA1305 project, the Association of Commercial Aquaponics Companies (ACAC 2018) was founded, currently involving 25 companies from all over Europe, only about a third of which focuses on food production. Others offer mostly aquaponics-related services such as engineering and consulting (Thorarinsdottir 2015).

18.5 Horticulture Side of Commercial Aquaponics in Europe

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Petrea et al. (2016) conducted a comparative cost-effective analysis on different aquaponics setups, utilising five different crops: baby leaf spinach, spinach, basil, mint and tarragon in deepwater culture and light expanded clay aggregate (LECA). Whilst the study was conducted in very small systems without taking into account any upscaling opportunity or potential, several aspects of the presented results are worth discussing. The grow beds have been illuminated in different lighting regimes with fluorescent bulbs and metal halide grow lights. The cost comparisons of the electricity illuminates the significant share plant lighting has on overall electricity cost. Furthermore, the analysis sheds light on the importance of sensible crop selection. Whilst tarragon is referenced as what is often called a “high-value crop” earlier in the text, the later economic crop yield analysis shows that other crops, basil and mint, generate a higher economic value per grow bed area (Petrea et al. 2016, p. 563).

18.6 Aquaculture Side of Commercial Aquaponics in Europe

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Starting a business in temperate climate regions of Europe or Northern America requires a larger investment since the systems have to be kept frost-free requiring more electrical energy for plant lighting when operated throughout the year. In Europe, there are two strong horticultural production powerhouses, one in Westland/NL and the other in Almeria, southern Spain. The market concentration is high and contribution margins are slim. As a result, some aquaponic producers presumed that in aquaponics the contribution margin from aquaculture is more interesting than that of horticulture, which is probably why some of the few commercial operators chose to oversize the aquaculture part of the setup. This can lead to technical issues because a larger quantity of nutrients than required by the plant side is being produced in the aquaculture side. The excess process water has to be discarded (Excursion Graber 2016 and Interview Echternacht 2018), putting the sustainability claims of aquaponics in question. Christian Echternacht from ECF reports that the contribution margin of the aquaculture has been overestimated in early calculations, rendering the oversizing of the aquaculture part of the farm counterproductive for the overall profitability of the farm.

18.7 Public Acceptance and Market Acceptance

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The future of aquaponics production depends on public perception and the associated social acceptance in important stakeholder groups (Pakseresht et al. 2017). In addition to potential aquaponics plant operators, players at the wholesale and retail level as well as gastro-distributors and collective catering are important actors in supply chains. Moreover, consumers are key actors as they bring in the money into the supply chain at its end. Even though they have no direct economic stakes in aquaponics production, the general public as well as political and administrative bodies are important aspects to consider. The necessity of involving the aforementioned stakeholders is based on studies such as Vogt et al. (2016), who show that suitable framework conditions are an important basis for the establishment of innovative processes in food value chains. Technical developments without involving stakeholders run the risk of non-acceptance at the end of the research and development pipeline. In general, they build on a comprehensive understanding of a marketing philosophy with a multi-stakeholder approach.

18.8 Conclusion and Outlook

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As discussed in this chapter, economic evaluations of aquaponic systems are still a very complex and difficult task at present. Although aquaponics is sometimes presented as an economically superior method of food production, there is no evidence for such generalised statements. Up to now, there is hardly any reliable data available for a comprehensive economic evaluation of aquaponics. That is partly because there is not “one aquaponics system”, but there exist a variety of different systems operating in different locations under different conditions. For example, factors such as climatic conditions, which mainly affect the energy consumption of the systems, wage levels, workload required for operating the systems, and legal conditions have to be considered on the cost side. On the revenue side, factors such as the chosen fish-plant combination with its specific product prices, the option to manage the systems as organic production as well as the long-term public acceptance of the aquaponics systems and their products have an impact on the economic assessment. Not least, the economic evaluation of aquaponics in its strictest sense should be done in comparison to recirculating aquaculture systems and hydroponics systems as stand-alone systems.

19.1 Introduction

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Aquaponics is an integrated closed-loop multi-trophic food production system that combines elements of a recirculating aquaculture system (RAS) and hydroponics (Endut et al. 2011; Goddek et al. 2015; Graber and Junge 2009). Aquaponics is therefore discussed as a sustainable eco-friendly food production system, where nutrient-enriched water from fish tanks is recirculated and used to fertilize vegetable production beds, thus making good use of the valuable nutrients that in conventional aquaculture systems are discarded (Shafahi and Woolston 2014) and presents a potential solution to an environmental problem usually referred to as eutrophication of aquatic ecosystems.

19.2 Organic Regulations

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19.2.1 Organic Rules in Horticulture

The hydroponic production technology in the absence of an organic growth media cannot be certified as organic, which has proven to be a long-time effective barrier for the conversion of existing greenhouse vegetable producers to organic farming schemes (König 2004). For horticultural products, the specific EU regulation preventing products produced under ‘classical’ aquaponics systems to obtain an organic certification are the following:

834/2007 Regulation (12): ….Plants should preferably be fed through the soil eco-system and not through soluble fertilizers added to the soil

19.3 Discussion and Conclusions

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This chapter has attempted to clarify the regulatory aspects relevant to understanding why aquaponics presently is not eligible for organic certification in the EU and the USA. As in the EU, the main paradigm behind organic farming in the USA is briefly, to manage soils in a natural way. In the EU, organic certification decisions for organic aquaponics are not carried out by local authorities, whereas the USA has seen a growth in this type of action in the last few years as well as an increase in private peer-review certifications and decisions of individual organic certification agencies.

2.1 Introduction

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The term ’tipping point’ is currently being used to describe natural systems that are on the brink of significant and potentially catastrophic change (Barnosky et al. 2012). Agricultural food production systems are considered one of the key ecological services that are approaching a tipping point, as climate change increasingly generates new pest and disease risks, extreme weather phenomena and higher global temperatures. Poor land management and soil conservation practices, depletion of soil nutrients and risk of pandemics also threaten world food supplies.

2.2 Food Supply and Demand

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2.2.1 Predictions

Over the last 50 years, total food supply has increased almost threefold, whereas the world’s population has only increased twofold, a shift that has been accompanied by significant changes in diet related to economic prosperity (Keating et al. 2014). Over the last 25 years, the world’s population increased by 90% and is expected to reach the 7.6 billion mark in the first half of 2018 (Worldometers). Estimates of increased world food demand in 2050 relative to 2010 vary between 45% and 71% depending on assumptions around biofuels and waste, but clearly there is a production gap that needs to be filled. In order to avoid a reversal in recent downward trends undernourishment, there must be reductions in food demand and/or fewer losses in food production capacity (Keating et al. 2014). An increasingly important reason for rising food demand is per capita consumption, as a result of rising per capita income, which is marked by shifts towards high protein foods, particularly meat (Ehrlich and Harte 2015b). This trend creates further pressures on the food supply chain, since animal-based production systems generally require disproportionately more resources, both in water consumption and feed inputs (Rask and Rask 2011; Ridoutt et al. 2012; Xue and Landis 2010). Even though the rate of increasing food demand has declined in recent decades, if current trajectories in population growth and dietary shifts are realistic, global demand for agricultural products will grow at 1.1—1.5% per year until 2050 (Alexandratos and Bruinsma 2012).

2.3 Arable Land and Nutrients

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2.3.1 Predictions

Even as more food needs to be produced, usable land for agricultural practices is inherently limited to roughly 20—30% of the world’s land surface. The availability of agricultural land is decreasing, and there is a shortage of suitable land where it is most needed, i.e. particularly near population centres. Soil degradation is a major contributor to this decline and can generally be categorized in two ways: displacement (wind and water erosion) and internal soil chemical and physical deterioration (loss of nutrients and/or organic matter, salinization, acidification, pollution, compaction and waterlogging). Estimating total natural and human-induced soil degradation worldwide is fraught with difficulty given the variability in definitions, severity, timing, soil categorization, etc. However, it is generally agreed that its consequences have resulted in the loss of net primary production over large areas (Esch et al. 2017), thus restricting increases in arable and permanently cropped land to 13% in the four decades from the early 1960s to late 1990s (Bruinsma 2003). More importantly in relation to population growth during that time period, arable land per capita declined by about 40% (Conforti 2011). The term ‘arable land’ implies availability of adequate nutrients to support crop production. To counteract nutrient depletion, worldwide fertilizer consumption has risen from 90 kg/ha in 2002 to 135 kg in 2013 (Pocketbook 2015). Yet the increased use of fertilizers often results in excesses of nitrate and phosphates ending up in aquatic ecosystems (Bennett et al. 2001), causing algal blooms and eutrophication when decaying algal biomass consumes oxygen and limits the biodiversity of aquatic life. Largescale nitrate and phosphate-induced environmental changes are particularly evident in watersheds and coastal zones.

2.4 Pest, Weed and Disease Control

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2.4.1 Predictions

It is generally recognized that control of diseases, pests and weeds is a critical component of curbing production losses that threaten food security (Keating et al. 2014). In fact, increasing the use of antibiotics, insecticides, herbicides and fungicides to cut losses and enhance productivity has allowed dramatic increases in agricultural output in the latter half of the twentieth century. However, these practices are also linked to a host of problems: pollution from persistent organic compounds in soils and irrigation water, changes in rhizobacterial and mycorrhizal activity in soils, contamination of crops and livestock, development of resistant strains, detrimental effects on pollinators and a wide range of human health risks (Bringezu et al. 2014; Ehrlich and Harte 2015a; Esch et al. 2017; FAO 2015b). Tackling pest, weed and disease control in ways that reduce the use of these substances is mentioned in virtually every call to provide food security for a growing world population.

2.5 Water Resources

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2.5.1 Predictions

Fig. 2.1 Water footprint (L per kg). Fish in RAS systems use the least water of any food production system

In addition to requiring fertilizer applications, modern intensive agricultural practices also place high demands on water resources. Among biochemical flows (Fig. 2.1), water scarcity is now believed to be one of the most important factors constraining food production (Hoekstra et al. 2012; Porkka et al. 2016). Projected global population increases and shifts in terrestrial water availability due to climate change, demand more efficient use of water in agriculture. As noted previously, by 2050, aggregate agriculture production will need to produce 60% more food globally (Alexandratos and Bruinsma 2012), with an estimated 100% more in developing countries, based on population growth and rising expectations for standards of living (Alexandratos and Bruinsma 2012; WHO 2015). Famine in some regions of the world, as well as malnutrition and hidden hunger, indicates that the balance between food demand and availability has already reached critical levels, and that food and water security are directly linked (McNeill et al. 2017). Climate change predictions suggest reduced freshwater availability, and a corresponding decrease in agricultural yields by the end of the twenty-first century (Misra 2014).

2.6 Land Utilization

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2.6.1 Predictions

Globally, land-based crops and pasture occupy approximately 33% of total available land, and expansion for agricultural uses between 2000 and 2050 is estimated to increase by 7—31% (350—1500 Mha, depending on source and underlying assumptions), most often at the expense of forests and wetlands (Bringezu et al. 2014). While there is currently still land classed as ‘good’ or ‘marginal’ that is available for rain-fed agriculture, significant portions of it are far from markets, lack infrastructure or have endemic diseases, unsuitable terrain or other conditions that limit development potential. In other cases, remaining lands are already protected, forested or developed for other uses (Alexandratos and Bruinsma 2012). By contrast, dryland ecosystems, defined in the UN’s Commission on Sustainable Development as arid, semiarid and dry subhumid areas that typically have low productivity, are threatened by desertification and are therefore unsuitable for agricultural expansion but nevertheless have many millions of people living in close proximity (Economic 2007). These facts point to the need for more sustainable intensification of food production closer to markets, preferably on largely unproductive lands that may never become suitable for soil-based farming.

2.7 Energy Resources

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2.7.1 Predictions

As mechanization spreads globally, open-field intensive agriculture increasingly relies heavily on fossil fuels to power farm machinery and for transportation of fertilizers as well as farm products, as well as to run the equipment for processing, packaging and storage. In 2010, the OECD International Energy Agency predicted that global energy consumption would grow by up to 50% by 2035; the FAO has also estimated that 30% of global energy consumption is devoted to food production and its supply chain (FAO 2011). Greenhouse gas (GHG) emissions associated with fossil fuels (approximately 14% in lifecycle analysis) added to those from fertilizer manufacturing (16%) and nitrous oxide from average soils (44%) (Camargo et al. 2013), all contribute substantially to the environmental impacts of farming. A trend in the twenty-first century to produce crop-based biofuels (e.g. corn for ethanol) to replace fossil fuels has increased pressure on the clearing of rainforests, peatlands, savannas and grasslands for agricultural production. However, studies point to creation of a ‘carbon debt’ from such practices, since the overall release of COsub2/sub exceeds the reductions in GHGs they provide by displacing fossil fuels (Fargione et al. 2008). Arguably a similar carbon debt exists when clearing land to raise food crops via conventional agriculture that relies on fossil fuels.

2.8 Summary

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As the human population continues to increase, there is increasing demand for highquality protein worldwide. Compared to meat sources, fish are widely recognized as being a particularly healthy source of protein. In relation to the world food supply, aquaculture now provides more fish protein than capture fisheries (FAO 2016). Globally, human per capita fish consumption continues to rise at an annual average rate of 3.2% (1961—2013), which is double the rate of population growth. In the period from 1974 to 2013, biologically unsustainable ‘overfishing’ has increased by 22%. During the same period, the catch from what are deemed to be ‘fully exploited’ fisheries has decreased by 26%. Aquaculture therefore provides the only possible solution for meeting increased market demand. It is now the fastest growing food sector and therefore an important component of food security (ibid.)

20.1 Introduction

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Regulatory frameworks can have a decisive influence on the implementation of sustainable technologies. However, there are currently no specific regulations or policies for aquaponics in the European Union (EU) or most of its member states. One of the reasons perhaps is that it falls at the intersection of various larger fields (industrial aquaculture, wastewater recycling, hydroponics, urban aquaculture), wherein producers are subject to a variety of potentially disparate and conflicting regulations. The following chapter provides an overview of the regulatory framework for aquaponics and gives some perspectives on how the development of aquaponics could be supported through EU policy. It builds on the work by Koenig et al. (2018) who have analyzed aquaponics through the theoretical framework for emerging technological innovation systems (see Bergek et al. 2008) and have shown how development pathways for this aquaponics might be influenced by institutional conditions.

20.2 Legal Framework for Aquaponics

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In this first section, our goal is to provide an overview of relevant regulations for the construction and operation of aquaponics facilities and the marketing of aquaponically produced products. We focus specifically on Germany, as it is impossible to extrapolate across the EU given that several important regulations, especially regarding zoning and construction, have not been harmonized across the EU. Although we focus on the German context, similar findings regarding planning law have also been reported in other countries (Joly et al. 2015).

20.3 Aquaponics and EU Policies

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National policies can only be analyzed for each individual country. We therefore concentrate on relevant EU policies.

20.3.1 Overview of Relevant EU Policies

The Common Fisheries Policy (CFP) and the Common Agricultural Policy (CAP) apply to the aquaculture and hydroponics components of aquaponics, respectively (European Commission 2012, European Commission 2013). Policies on food safety, animal health and welfare, plant health, and the environment (waste and water) also apply.

20.3.1.1 Common Agricultural Policy

The Rural Development Policy, also referred to as the second pillar of CAP, focuses on increasing competitiveness and promoting innovation (Ragonnaud 2017). Each member state has at least one rural development program. Most countries have set goals to provide training, restructure and modernize existing farms, set up new farms, and reduce emissions. Measures against excessive use of inorganic fertilizers were introduced in the CAP as well as environmental policies and are regulated through the EU’s Nitrates Directive (Directive 91/676/EEC 1991) and the Water Framework Directive (WFD).

20.4 Overall Conclusions and Policy Recommendations

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Aquaponics is not only at the nexus of different technologies but also at the nexus of different regulatory and policy fields. While it may provide solutions to various sustainability goals, it seems to fall in the cracks between established legal and political categories. To add to the complexity, the development of aquaponics is affected by regulation from different levels of government. For example, facilitation of urban agriculture has to come from the national or even subnational level, as the EU has no competence in planning law. Major regulatory incentives for the implementation of aquaponic technology could probably be set in water law, which falls under national and EU competence. Implementation of aquaponics could gain significant traction, if aquaculture operations had the obligation or at least financial incentives to deal with wastewater themselves. However this would require a major change in the current regulatory approach.

21.1 Introduction

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Aquaponics has been recognized as one of “ten technologies which could change our lives” by merit of its potential to revolutionize how we feed growing urban populations (Van Woensel et al. 2015). This soilless recirculating growing system has stimulated increasing academic research over the last few years and inspired interest in members of the public as documented by a high ratio of Google to Google Scholar search results in 2016 (Junge et al. 2017). For a long time, aquaponics has been primarily practiced as a backyard hobby. It is now increasingly used commercially due to strong consumer interest in organic, sustainable farming methods. A survey conducted by the CITYFOOD team at the University of Washington in July 2018 shows that the number of commercial aquaponic operations has rapidly increased over the last 6 years. This focused search for aquaponic operations identified 142 active for-profit aquaponic operations in North America. Based on online information, 94% of the farms have started their commercial-scale operation since 2012; only nine commercial aquaponic farms have been in operation for more than 6 years (Fig. 21.1).

21.2 Classification of Controlled Environment Aquaponics

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The term aquaponics is used to describe a wide range of different systems and operations, greatly varying in size, technology level, enclosure type, main purpose, and geographic context (Junge et al. 2017). The first version of the classification criteria for aquaponic farms included stakeholder objectives, tank volume, and parameters describing aquaculture and hydroponic system components (Maucieri

img src=“https://cdn.farmhub.ag/thumbnails/c7770dc3-ea11-4f37-94b9-64f54d9a1d1e.jpg" style=“zoom:48%;” /

Fig. 21.3 Classification criteria for identifying aquaponic farm types

et al. 2018). Additional work was undertaken by a large group of researchers to further define aquaponics and to present a nomenclature based on international consensus (Palm et al. 2018). This led to a comprehensive discussion on system types and scales and most importantly a definition of aquaponics which is: “the majority (> 50%) of nutrients sustaining the optimal plant growth must derive from waste originating from feeding the aquatic organisms.” However, both definitions focus on the growing systems and do not consider other essential aspects of a functioning commercial aquaponics farm. As aquaponic operations become part of local economies, classification criteria identified by interdisciplinary research in fields like architecture, economics, and sociology will also become essential.

21.3 Enclosure Typologies and Case Studies of Commercial Farms

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This further investigation focuses on defining aquaponic classification criteria at the enclosure level to complement existing system-level definitions. The enclosure types discussed here work with different construction systems, levels of technological control, passive climate control strategies, and energy sources to achieve an appropriate indoor climate. The best application of each enclosure typology depends primarily on the size of operation, geographic location, local climate, targeted fish and crop species, required parameters of the systems it houses, and the budget. This study identifies five different enclosure typologies and defines the characteristics of indoor spaces that house aquaculture infrastructure.

21.4 Assessing Enclosure Typologies and Possible Applications

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The actual performance of aquaponic farms depends on many case-specific factors. Some preliminary conclusions about enclosure typologies’ advantages, challenges, and possible applications can be drawn from the comparison of a relatively small set of case studies. An empirical study of a more significant number of existing case studies will be needed to establish a correlation between enclosure type, geographic location, and commercial success.

Medium-tech greenhouses offer a commercially-feasible option for aquaponic operations only in temperate climates with mild winters and moderate summers, due to their limited environmental control capability. In locations that do not require much heating and cooling, farms using this greenhouse typology can operate in a resource-efficient manner with lower upfront investment for their enclosure. These farms usually operate on a lower budget and include the fish tanks in the same greenhouse, which limits their selection of fish species to those with a large temperature tolerance and draws their commercial focus to the production of lettuce, leafy greens, and herbs.

21.5 Impact Assessment as a Design Framework

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The growth of aquaponics and generalized claims that aquaponics is more sustainable than other forms of food production has stimulated discussion and research into how sustainable these systems actually are. Life cycle assessment (LCA) is one key quantification method that can be used to analyze sustainability in both agriculture and the built environments by evaluating environmental impacts of products throughout their lifespan. For a building, an LCA can be divided into two types of impact — embodied impact which includes material extraction, manufacture, construction, demolition and disposal/reuse of said materials, and operational impact which refers to building systems maintenance (Simonen 2014). Similarly, conducting an assessment of an agricultural product can be also divided into the structural impact of the building envelope and system infrastructure, production impact associated with continuous cultivation and post-harvest impact of packaging, storage, and distribution (Payen et al. 2015). Conducting an LCA of an aquaponic farm requires the simultaneous understanding of both building and agricultural impacts since there is an overlap in the envelope’s operational phase with a crop’s production phase. The way a building operates its heating, cooling, and lighting systems directly influences the cultivation of the crop; conversely, different types of crops require different environmental conditions. Numerous studies exist comparing LCA results for different building types situated in different contexts (Zabalza Bribián et al. 2009). Similarly, LCA has been used by the agricultural sector to compare efficiencies for different crops and cultivation systems (He et al. 2016; Payen et al. 2015). Evaluating the performance of controlled environment agriculture and aquaponics in particular requires a skillful integration of the two methodologies into one assessment (Sanyé-Mengual 2015).

21.6 Integrated Urban Aquaponics

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When deliberately designed with respect to environmental impact, aquaponic farms can become part of a resource-efficient urban food system. No aquaponic farm operates in isolation since when crops are harvested and reach the farm gate, they enter a larger socioeconomic food network as fish and produce is distributed to customers. At this stage, the performance of aquaponic farms is no longer confined to the growing system and envelope — economics, marketing, education, and social outreach are also involved. Urban aquaponic farms will need to operate as competitive businesses and good neighbors to be successfully integrated into city life.

21.7 Conclusions

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There is an array of criteria that contribute to the performance of each farm and their number grows with the number of disciplines involved in this the interdisciplinary field of aquaponics. Of note is an earlier study that has provided a definition of aquaponics and a classification of the types of aquaponics based on size and system (Palm et al. 2018). Many criteria for the analysis of the enclosure type identified in this study stem from immediate farm context — local climate, the quality of the built environment context, energy sourcing practices, costs, market, and local regulatory frameworks. An aquaponic greenhouse in a rural context performs differently than one in a city, just as farms in arid climates do not share the same requirements as their counterparts in colder areas. In general, greenhouses classified as medium-tech and passive solar offer a lower cost, environmentally sustainable enclosure option, currently only used by smaller aquaponic operations. However, due to their intentionally limited level of technical environmental controls, they only perform well in specific climate zones. In comparison, high-tech and rooftop greenhouses can be technically implemented anywhere, though in extreme climate conditions they generate high operational costs and larger environmental footprints. Recent case studies show that indoor growing facilities can be financially feasible, but due to their exclusive reliance on electrical lighting, their resource use efficiency and environmental footprint are of concern. Further research is needed to establish the relationship of specific aquaponic farms and their enclosures to existing resource networks. This work can help connect aquaponics to research done on urban metabolism.

22.1 Introduction

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Aquaponics is not only a forward-looking food production technology; it also promotes scientific literacy and provides a very good tool for teaching the natural sciences (life and physical sciences) at all levels of education, from primary school (Hofstetter 2007, 2008; Bamert and Albin 2005; Bollmann-Zuberbuehler et al. 2010; Junge et al. 2014) to vocational education (Baumann 2014; Peroci 2016) and at university level (Graber et al. 2014).

An aquaponic classroom model system provides multiple ways of enriching classes in Science, Technology, Engineering, and Mathematics (STEM). The “hands-on” approach also enables experiential learning, which is the process of learning through physical experience, and more precisely the “meaning-making” process of an individual’s direct experience (Kolb 1984). Aquaponics can thus become an enjoyable and effective way for learners to study STEM content. It can also be used for teaching subjects such as business and economics, addressing issues such as sustainable development, environmental science, agriculture, food systems, and health (Hart et al. 2013).

22.2 General Scenarios for Implementing Aquaponics in Curricula

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The introduction of aquaponics into schools may be an aspiration, but in many countries, primary and secondary schools have rigid curricula with learning objectives that must be met by the end of each school year. Commonly, these objectives, called attainment terms or outcome competencies, are course-specific and defined by the education authorities. Thus, this calls for a well-thought-out strategy to successfully introduce an aquaponics in school classes. In comparison, colleges and universities have more freedom to map out their own curricula.

22.3 Aquaponics in Primary Schools

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According to the International Standard Classification of Education (UNESCO-UIS 2012), primary education (or elementary education in American English) at ISCED level 1 (first 6 years) is typically the first stage of formal education. It provides children from the age of about 5—12 with a basic understanding of various subjects, such as maths, science, biology, literacy, history, geography, arts, and music. It is therefore designed to provide a solid foundation for learning and understanding core areas of knowledge, as well as personal and social development. It focuses on learning at a basic level of complexity with little, if any, specialization. Educational activities are often organized with an integrated approach rather than providing instruction in specific subjects.

22.4 Aquaponics in Secondary Schools

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According to the ISCED classification (UNESCO-UIS 2012), secondary education provides learning and educational activities building on primary education and preparing for both first labor market entry as well as post-secondary non-tertiary and tertiary education. Broadly speaking, secondary education aims to deliver learning at an intermediate level of complexity.

While at primary education level, students are mainly directed toward observational and descriptive exercises on organisms and processes in an aquaponics, students from secondary schools can be educated in understanding dynamic processes. Aquaponics enables this increased complexity and fosters system thinking (Junge et al. 2014).

22.5 Aquaponics in Vocational Education and Training

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UNESCO-UIS/OECD/EUROSTAT (2017) defines vocational education programs as “designed for learners to acquire the knowledge, skills and competencies specific to a particular occupation, trade, or class of occupations or trades. Successful completion of such programs leads to labour market relevant, vocational qualifications acknowledged as occupationally-oriented by the relevant national authorities and/or the labour market” (UNESCO, 2017).

In order to educate future aquaponic farmers and aquaponic technicians, the training has to include the professional operation of aquaponics. Therefore, the training environment needs to be state-of-art. However, the setting does not have to be large: 30 msup2/sup should suffice (Podgrajsek et al. 2014, Examples 22.5 and 22.6). Such systems should be planned and built by professionals as they require complex monitoring and operation.

22.6 Aquaponics in Higher Education

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Higher education programs need to be adapted to meet the expectations of the new millennium, such as long-term food security and sovereignty, sustainable agriculture/food production, rural development, zero hunger, and urban agriculture. These important drivers mean that higher education institutions involved in the areas of food production can play a key role in the teaching of aquaponics through both capacity development and knowledge creation and sharing. Additionally, it is clear that the interest in teaching and learning aquaponics is increasing (Junge et al. 2017).

22.7 Does Aquaponics Fulfill Its Promise in Teaching? Assessments of Teaching Units by Teachers

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22.7.1 Teacher Interviews in Play-With-Water

Aquaponic teaching units were assessed in the FP6 project “Play-With-Water” on seven separate occasions in three countries (Sweden, Norway, Switzerland). This involved six schools (1 school in Norway, 1 in Sweden, and 4 in Switzerland) where the age of students ranged between 7 and 14 years. Six teachers were asked to keep a diary, which they then used to answer an online questionnaire complemented with phone interviews, which are summarized in Table 22.5.

22.8 Does Aquaponics Fulfill Its Promise in Teaching? Evaluation of Students' Responses to Aquaponics

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22.8.1 EU FP6 Project “WasteWaterResource”

The aim of the Waste Water Resource project was to assemble, develop, and assess teaching and demonstration material on ecotechnological research and methods for pupils aged between 10 and 13 years (http://www.scientix.eu/web/guest/projects/ project-detail?articleId=95738). The teaching units were assessed in order to improve the methods and content and maximize learning outcomes. Based on discussions with educational professionals, the assessment was based on a simple approach using questionnaires and semi-structured interviews. Teachers assessed the units by answering the online questionnaire (see Sect. 22.7.1). The aquaponic units were evaluated in Sweden (in the Technichus Science Center, and in Älandsbro skola in Härnösand), and in Switzerland.

22.9 Discussion and Conclusions

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An aquaponics is a perfect example of a system that can bring nature closer to a classroom and can be used as the starting point for a host of educational activities at both primary and secondary school levels. A model system, together with corresponding didactic methods, serves to make natural processes more tangible to pupils. This, in turn, helps to develop the necessary competencies for dealing with the complexity and problems of the environment, and promotes a sense of responsibility toward humanity. Creating the opportunity for hands-on experience with nature and natural elements such as water, fish, and plants also develops environmental consciousness and a greater understanding of the potential for practical solutions and a willingness to act on this knowledge.

23.1 Introduction

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Sustainable food production and consumption are important societal challenges. Growing populations, scarcity of arable land, and urbanization are all important factors in this area, leading to a growing interest in new sustainable food production technologies, which are not necessarily confined to maritime or rural settings. Aquaponics is one of these technologies that has received increased attention, in particular, since it can easily be applied also in urban environments. These new technologies, including aquaponics, also offer new opportunities as learning tools for people of all ages, but it is particularly appealing for young people at school. This chapter reports on the findings from the educational Growing Blue & Green (GBG) program that has been developed and tested in educational settings in the Greater Copenhagen area. Additional studies also suggest that there appears to be potential for using aquaponics as a key way of learning about sustainable food production in a wide spectrum of academic disciplines at school since it can readily be integrated into the existing educational curriculum. A few studies have examined the application of aquaponics in an educational context. Graber et al. (2014) studied the potential of aquaponics as a food production method for urban areas teaching seventh-grade pupils sustainability issues in science classes. The idea behind the concept was to introduce and train students on “systems thinking” by combining fish and plant growing. Junge et al. (2014) showed that the students’ ability to think in a systematic way improved significantly as a result. The study also suggested that building on social learning in groups the students developed greater teamwork skills. However, apart from these examples, aquaponics literature is relatively limited and most of the available articles have focused on the technological aspects of the systems. This chapter attempts to fill this knowledge gap by exploring the opportunities for integrating aquaponic technology into school learning and to uncover some of the constraints as well as the opportunities.

23.2 Conceptual Foundation

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Supporting Sustainable Development (SD) of the food system through educational efforts can be expected to be a good investment, as school children are the future policy makers and producers.

According to Shephard (2008), educators and particularly higher educators have traditionally focused on the cognitive domain of learning with no much emphasis being put on primary education. We hold the view that using appropriate learning tools at primary school level can be an essential pillar to bringing about long-term positive change in societies. These can be realized though alternative learning and teaching approaches, different from traditional deductive approaches such as “learning by doing” and “experiential learning” pioneered by Dewey (1997) in his work experience and education. In our research work, we present a type of extracurricular dimensional perspective, where we add to pupils’ learning outcomes by tapping into the affective domain, which focuses on interests, attitudes, appreciations, values, changing behaviors, and emotional sets or biases (Shephard et al. 2015). Practical aquaponics promises to deliver a hands-on problem-based inductive learning tool for education.

23.3 Methods

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In the context of this chapter, three data sources were used including (a) an exploratory study on the educational opportunities at school (Bosire et al. 2016), (b) a feasibility study carried out among teachers (Bosire and Sikora 2017), and (c) the eGBG study (Toth and Mikkelsen 2018).

The first study (a) was carried out as an exploration of the opportunities and challenges of using aquaponics as an educational tool. The study aimed at investigating to what extent it makes sense to use aquaponics in school teaching. Data from three (N = 3) independent qualitative interviews were collected. The informants were (1) a biology teacher engaged in natural science teaching at primary school; (2) a consultant entrepreneur, which is an aquaponic expert, too; and (3) one local aquaponic bio-farmer. The data analysis procedure was inspired by the future workshop approach (Jungk and Müllert 1987), leading to a categorization and evaluation according to the three categories of critique, fantasy, and strategy.

23.4 Findings and Discussion

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From the first study, the findings showed that visions of a new way of teaching with inclusion of the modern technology could be perceived as an advantage in influencing transformational processes at school. Nevertheless, this process requires some critical, practical, and theoretical considerations for implementation of the system to make it successful and sustainable in the long term. Some of the positive issues from the users’ perspectives included a wide range of application in the subjects of biology, mathematics, science, and more. Reduction pollution and efficient resource usage; flexibility of the system setup, e.g., on rooftops; and the production of (organic-like*) twin products (fish and plant foods). Potential limitations included time constraints, lack of financial resources, as well as the need for frequent care and maintenance. (* In the EU, current legislation provides that only vegetal produce grown in soil may be considered “organic.” This is not the case, e.g., in the USA, where aquaponic produce can be grown organically and legally sold as being organic.)

24.1 Introduction

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Social enterprises, as distinct from traditional private or corporate enterprise, aim to deliver products and services that cater to basic human needs. For a social enterprise, the primary motivation is not maximizing profit but building social capital; economic growth is therefore only part of a much broader mandate that includes social services such as rehabilitation, education and training, as well as environmental protection. There is growing interest in aquaponics among social enterprises, because it represents an effective tool to help them deliver their mandate. For example, aquaponics can integrate livelihood strategies to secure food and small incomes for landless and poor households. Domestic production of food, access to markets, and the acquisition of skills are invaluable tools for securing the empowerment and emancipation of women in developing countries, and aquaponics can provide the foundation for fair and sustainable socioeconomic growth (Somerville et al. 2014). This chapter presents some examples of recent initiatives by social enterprises using aquaponics.

24.2 Health, Well-being, and Skills

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Aquaponics offers an innovative form of therapeutic horticulture, a nature-based approach that can promote well-being for people with mental health problems through using a range of green activities such as gardening and contact with animals. Over the past decade, a number of social enterprises have emerged that provide therapeutic horticulture programs for improving the well-being of local communities. The social enterprise approach builds on “social firms” by facilitating people with mental health problems to develop new skills and re-engage with the workplace. A social firm is a specific type of social enterprise where the social mission is to create employment, work experience, training, and volunteering opportunities, within a supportive and inclusive environment, for people who face significant barriers to employment and in particular for people with a disability (including mental ill health, and learning disability), abuse issues, a prison record, or homeless issues (Howarth et al. 2016).

24.3 Food Security and Food Sovereignty

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Food security exists when all people, at all times, have physical and economic access to sufficient, safe, and nutritious food that meets their dietary needs and food preferences for an active and healthy life (Allison 2011). There are four food security pillars, which define, defend, and measure food security status locally, nationally, and internationally. These are food availability, food accessibility, food utilization, and food stability. Food availability is achieved when nutritious food is available at all times for people to access, while food accessibility is achieved when people at all times have the economic ability to obtain nutritious food available according to their dietary preferences. Food utilization is achieved when all food consumed is absorbed and utilized by the body to make a healthy active life possible, and food stability is achieved when all the other pillars are achieved (Faber et al. 2011).

24.4 The Viability of Aquaponics Social Enterprises

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The examples above illustrate some of the different business models adopted by aquaponics social enterprises. Whether they will continue to thrive and grow or, like Growing Power, ultimately fail, remains to be seen. In the case of Growing Power, potential reasons for its collapse include Will Allen’s inability to empower and retain an operational management team, and a lack of oversight by board members, which compromised the organization’s financial health (Satterfield 2018). An in-depth analysis of two aquaponics social enterprises conducted in 2012—2013 revealed four distinct factors what were significant to their survival (Laidlaw and Magee 2016). Sweet Water Organics (SWO) began as an urban aquaponic farm in a large, disused, inner city industrial building in Milwaukee in 2008. It was funded primarily by its founders in order to develop creative capacity, employment opportunities, and chemical-free, fresh, and affordable food for the local community. In 2010, a new organization, Sweet Water Farms (SWF), was split from SWO, with the idea that they would grow as a mutually supportive, cohesive hybrid organization, including both a for-profit commercial urban farm (SWO) and a not-for-profit aquaponics “academy” (SWF). SWF managed volunteer operations and hosted training and education programs at the Sweet Water urban farm, while developing programs on a local (Milwaukee and Chicago), regional, national, and international scale. Sweet Water had a loyal following among local restaurateurs and fresh food stores for its lettuce and sprouts produce, and sold its fish to a single wholesaler. However, the hybrid not-for-profit/for-profit enterprise model proved to be challenging, as both sides of the organization struggled to identify their role in relation to the other. While each side had a different structure relating to their operational character, and although their operations frequently overlapped, their strategic planning and visions sometimes did not. After 3 years of operation, SWO had still not managed to make a profit, and in 2011 the Milwaukee municipal government awarded a $250,000 loan on condition that 45 jobs would be created by 2014. In October 2012, SWO had 11—13 permanent employees, but was still being sustained through loans financing and equity investment. By June 2013, as loan repayments fell due and the job creation targets were not met, the for-profit arm of Sweet Water went into liquidation, and SWF took over as the primary operator of the Sweet Water urban farm. Currently, SWF operates entirely as an educational and advisory enterprise run by volunteers and a small team of part-time employees, and no longer supplies restaurants with produce (Laidlaw and Magee 2016).

24.5 Conclusions

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In “Ten technologies which could change our lives” (European Parliamentary Research Service, 2015), aquaponic systems were singled out as a solution for developing innovative and sustainable food sources for Europe which, through shortening of supply chains, could improve food security and food systems resilience. However, the technology is still newly emerging and as yet relatively undeveloped, and as the study by Laidlaw and Magee (2016) highlights, the viability of an aquaponics social enterprise depends not only on stakeholder commitment, thorough market analysis, clear governance structures, and a robust business plan, but also on external factors, such as the local political context and regulations.

3.1 Introduction

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Recirculating aquaculture systems (RAS) describe intensive fish production systems which use a series of water treatment steps to depurate the fish-rearing water and facilitate its reuse. RAS will generally include (1) devices to remove solid particles from the water which are composed of fish faeces, uneaten feed and bacterial flocs (Chen et al. 1994; Couturier et al. 2009), (2) nitrifying biofilters to oxidize ammonia excreted by fish to nitrate (Gutierrez-Wing and Malone 2006) and (3) a number of gas exchange devices to remove dissolved carbon dioxide expelled by the fish as well as/or adding oxygen required by the fish and nitrifying bacteria (Colt and Watten 1988; Moran 2010; Summerfelt 2003; Wagner et al. 1995). In addition, RAS may also use UV irradiation for water disinfection (Sharrer et al. 2005; Summerfelt et al. 2009), ozonation and protein skimming for fine solids and microbial control (Attramadal et al. 2012a; Gonçalves and Gagnon 2011; Summerfelt and Hochheimer 1997) and denitrification systems to remove nitrate (van Rijn et al. 2006).

3.2 Review of Water Quality Control in RAS

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RAS are complex aquatic production systems that involve a range of physical, chemical and biological interactions (Timmons and Ebeling 2010). Understanding these interactions and the relationships between the fish in the system and the equipment used is crucial to predict any changes in water quality and system performance. There are more than 40 water quality parameters than can be used to determine water quality in aquaculture (Timmons and Ebeling 2010). Of these, only a few (as described in Sects. 3.2.1, 3.2.2, 3.2.3, 3.2.4, 3.2.5, 3.2.6 and 3.2.7) are traditionally controlled in the main recirculation processes, given that these processes can rapidly affect fish survival and are prone to change with the addition of feed to the system. Many other water quality parameters are not normally monitored or controlled because (1) water quality analytics may be expensive, (2) the pollutant to be analysed can be diluted with daily water exchange, (3) potential water sources containing them are ruled out for use or (4) because their potential negative effects have not been observed in practice. Therefore, the following water quality parameters are normally monitored in RAS.

3.3 Developments in RAS

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The last few years have seen an increase in the number and sizes of recirculating aquaculture farms, especially in Europe. With the increase in acceptance of the technology, improvements over traditional engineering approaches, innovations and new technical challenges keep emerging. The following section describes the key design and engineering trends and new challenges that recirculating aquaculture technology is facing.

3.3.1 Main Flow Oxygenation

The control of dissolved oxygen in modern RAS aims to increase the efficiency of oxygen transfer and decrease the energy requirements of this process. Increasing the oxygen transfer efficiency can be achieved by devising systems which retain oxygen gas in contact with water for longer, while a decrease in energy requirements may be achieved by the use of low-head oxygen transfer systems or using systems which do not use electricity at all, such as liquid oxygen systems connected to oxygen diffusers operating only by pressure. A defining factor of low-head oxygenators is the relatively low dissolved concentration that can be achieved compared to highpressure systems. To overcome this limitation, low-head oxygenation devices are strategically placed to treat the full recirculating flow instead of using a smaller bypass of highly supersaturated water, thus ensuring sufficient mass transport of oxygen. Using oxygenation devices installed in the main recirculating flow generates savings in electricity consumption because the use of energy-intensive high-pressure systems that are necessary to achieve high DO concentrations in small flows is avoided. Low-head oxygenation systems may also reduce the amount of pumping systems needed, as high-pressure oxygenation systems are commonly placed on a bypass in the pipelines going to the fish tanks. In contrast, low-head oxygenation devices tend to be comparatively larger because of their need to handle larger flows and thus, their initial cost may be higher. Examples of devices that can treat the totality of the flow include the low-head oxygenator (LHO) (Wagner et al. 1995), operated by gravity as water is firstly pumped into a biofilter and a packed column (Summerfelt et al. 2004), low-head oxygen cones, variants of the Speece Cone (Ashley et al. 2008; Timmons and Losordo 1994) operated at low pressure, the deep shaft cones (Kruger Kaldnes, Norway), also a variant of the Speece cone designed to reach higher operating pressures by means of increased hydrostatic pressure resulting from placing the devices lower than the fish tanks and pump sumps, the U-tube oxygenator and its design variants such as the Farrell tube or the patented oxygen dissolver system (AquaMAOF, Israel) and the use of diffused oxygenation in deep fish tanks (Fig. 3.5).

3.4 Animal Welfare Issues

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3.4.1 Introduction

During the last decade, fish welfare has attracted a lot of attention, and this has led to the aquaculture industry incorporating a number of husbandry practices and technologies specifically developed to improve this aspect. The neocortex, which in humans is an important part of the neural mechanism that generates the subjective experience of suffering, is lacking in fish and non-mammalian animals, and it has been argued that its absence in fish indicates that fish cannot suffer. A strong alternative view, however, is that complex animals with sophisticated behaviours, such as fish, probably have the capacity for suffering, though this may be different in degree and kind from the human experience of this state (Huntingford et al. 2006).

3.5 Scalability Challenges in RAS

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RAS are capital-intensive operations, requiring high funding expenditure on equipment, infrastructure, influent and effluent treatment systems, engineering, construction and management. Once the RAS farm is built, working capital is also needed until harvests and successful sales are achieved. Operational expenditures are also substantial and are mostly comprised of fixed costs such as rent, interest on loans, depreciation and variable costs such as fish feed, seed (fingerlings or eggs), labour, electricity, technical oxygen, pH buffers, electricity, sales/marketing, maintenance costs, etc.

3.6 RAS and Aquaponics

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Aquaponic systems are a branch of recirculating aquaculture technology in which plant crops are included to either diversify the production of a business, to provide extra water filtration capacity, or a combination of the two.

As a branch of RAS, aquaponic systems are bound to the same physical, chemical and biological phenomena that occur in RAS. Therefore, the same fundamentals of water ecology, fluid mechanics, gas transfer, water depuration etc. apply in more or less equal terms to aquaponics with the exception of water quality control, as plants and fish may have specific and different requirements.

4.1 Introduction

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In horticultural crop production, the definition soilless cultivation encompasses all the systems that provide plant production in soilless conditions in which the supply of water and of minerals is carried out in nutrient solutions with or without a growing medium (e.g. stone wool, peat, perlite, pumice, coconut fibre, etc.). Soilless culture systems, commonly known as hydroponic systems, can further be divided into open systems, where the surplus nutrient solution is not recycled, and closed systems, where the excess flow of nutrients from the roots is collected and recycled back into the system (Fig. 4.1).

4.2 Soilless Systems

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The intense research carried out in the field of hydroponic cultivation has led to the development of a large variety of cultivation systems (Hussain et al. 2014). In practical terms all of these can also be implemented in combination with aquaculture; however, for this purpose, some are more suitable than others (Maucieri et al. 2018). The great variety of systems that may be used necessitates a categorization of the different soilless systems (Table 4.1).

4.3 Types of Hydroponic Systems According to Water/ Nutrient Distribution

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4.3.1 Deep Flow Technique (DFT)

Deep flow technique (DFT), also known as deep water technique, is the cultivation of plants on floating or hanging support (rafts, panels, boards) in containers filled with 10—20 cm nutrient solution (Van Os et al. 2008) (Fig. 4.3). In AP this can be up to 30 cm. There are different forms of application that can be distinguished mainly by the depth and volume of the solution, and the methods of recirculation and oxygenation.

4.4 Plant Physiology

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4.4.1 Mechanisms of Absorption

Amongst the main mechanisms involved in plant nutrition, the most important is the absorption which, for the majority of the nutrients, takes place in ionic form following the hydrolysis of salts dissolved in the nutrient solution.

Active roots are the main organ of the plant involved in nutrient absorption. Anions and cations are absorbed from the nutrient solution, and, once inside the plant, they cause the protons (Hsup+/sup) or hydroxyls (OHsup-/sup) to exit which maintains the balance between the electric charges (Haynes 1990). This process, whilst maintaining the ionic equilibrium, can cause changes in the pH of the solution in relation to the quantity and quality of the nutrients absorbed (Fig. 4.6).

4.5 Disinfection of the Recirculating Nutrient Solution

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To minimize the risk of spreading soil-borne pathogens, disinfection of the circulating nutrient solution is required (Postma et al. 2008). Heat treatment (Runia et al. 1988) was the first method used. Van Os (2009) made an overview for the most important methods and a summary is given below. Recirculating of the nutrient solution opens possibilities to save on water and fertilizers (Van Os 1999). The big disadvantage of the recirculation of the nutrient solution is the increasing risk of spreading root-borne pathogens all over the production system. To minimize such risks, the solution should be treated before reuse. The use of pesticides for such a treatment is limited as effective pesticides are not available for all such pathogens, and if available, resistance may appear, and environmental legislation restricts discharge of water with pesticides (and nutrients) into the environment (European Parliament and European Council 2000). In addition, in AP systems, the use of pesticides exerts negative effects on fish health and cannot be carried out, even if hydroponic and AP parts of the system are in different rooms, because spraying of chemicals may enter the nutrient solution via condensation water or via direct spraying on the substrate slabs. In view of this, a biological control approach can be adopted to manage pest diseases, and this can be accessed via the EU Aquaponics Hub Fact Sheet (EU Aquaponics Hub). At the same time, similar problems can be observed for fish treatment using veterinary drugs that are not compatible with the plant’s cycle.

5.1 Introduction

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Aquaponics is a technology that is a subset of a broader agricultural approach known as integrated agri-aquaculture systems (IAAS) (Gooley and Gavine 2003). This discipline consists of integrating aquaculture practices of various forms and styles (mostly fin fish farming) with plant-based agricultural production. The rationale of integrated agri-aquaculture systems is to take advantage of the resources shared between aquaculture and plant production, such as water and nutrients, to develop and achieve economically viable and environmentally more sustainable primary production practices (Gooley and Gavine 2003). In essence, both terrestrial plant and aquatic animal production systems share a common resource: water. Plants are generally consumptive of water via transpiration and release it to the surrounding gaseous environment, whereas fish are generally less consumptive of water, but their contained culture produces substantial waste water streams due to accumulated metabolic wastes. Therefore, aquaculture may be integrated within the water supply pathway of plant production in non-consumptive ways so that two crops (fish and plants) may be produced from a water source that is generally used to produce one crop (plants).

5.2 A Definition of Aquaponics

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Aquaponics fits into the broader definition of integrated agri-aquaculture systems (IAAS). However, IAAS applies many different aquatic animal and plant production technologies in many contexts, whereas aquaponics is far more tightly associated with integrating tank-based fish culture technologies (e.g. recirculating aquaculture systems; RAS) with aquatic or hydroponic plant culture technologies (Lennard 2017). RAS technologies apply conserved and standard methods for the culture of fish in tanks with applied filtration to control and alter the water chemistry to make it suitable for fish (i.e. fast and efficient solid fish wastes removal, efficient, bacteriamediated conversion of potentially toxic dissolved fish waste ammonia to less toxic nitrate and oxygen maintenance via assisted aeration or directly injected oxygen gas) (Timmons et al. 2002). Hydroponics and substrate culture technologies apply conserved and standard methods for the culture of edible terrestrial plants within aquatic environments (i.e. the plants gain access to the nutrients required for growth via a water-based delivery method) (Resh 2013).

5.3 General Principles

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Even though the definition of aquaponics has not been entirely resolved, there are some general principles that are associated with the broad range of aquaponic methods and technologies.

Using the nutrients added to the aquaponic system as optimally and efficiently as possible to produce the two main products of the enterprise (i.e. fish and plant biomass) is an important and shared first principle associated with the technology (Rakocy and Hargreaves 1993; Delaide et al. 2016; Knaus and Palm 2017). There is no use in adding nutrients (which possess an inherent cost in terms of money, time and value) to a system to watch a high percentage of those nutrients are partitioned into processes, requirements or outcomes that are not directly associated with the fish and plants produced, or any intermediary life forms that may assist nutrient access by the fish and plants (i.e. microorganisms — bacteria, fungi, etc.) (Lennard 2017). Therefore, probably the most important general principle associated with aquaponics is to use the applied nutrients as efficiently as possible to achieve the optimised production of both fish and plants.

5.4 Water Sources

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Water is the key medium used in aquaponic systems because it is shared between the two major components of the system (fish and plant components), it is the major carrier of the nutrient resources within the system and it sets the overall chemical environment the fish and plants are cultured within. Therefore, it is a vital ingredient that may have a substantial influence over the system.

In an aquaponic system, water-based environment context, the source of water and what that source water contains chemically, physically and biologically are a major influence over the system because it sets a baseline for what is required to be added to the system by the various inputs of the system. These inputs, in turn, effect and set the environment that the fish and plants are cultured within. For example, some of the major inputs in terms of nutrients to any aquaponic system include, but are not limited to, the fish feed (a primary nutrient resource for the system), the buffers applied (which assist to control and set the pH values associated with both the fish and plant components) and any external nutrient additions or supplementations required to meet the nutrient needs of the fish and plants (Lennard 2017).

5.5 Water Quality Requirements

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Aquaponics represents an effort to control water quality so that all the present life forms (fish, plants and microbes) are being cultured in as close to ideal water chemistry conditions as possible (Goddek et al. 2015). If water chemistry can be matched to the requirements of these three sets of important life forms, efficiency and optimisation of growth and health of all may be aspired to (Lennard 2017).

Optimisation is important to commercial aquaponic production because it is only through optimisation that commercial success (i.e. financial profitability) may be realised. Therefore, water chemistry and water quality requirements within the aquaponic system are pivotal to the ultimate commercial and economic success of the enterprise (Goddek et al. 2015).

5.6 Applicable Fish Culture Technologies

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In aquaponics, the aquaculture portion of the integration equation is broadly applied in a tank-based context, where the fish are kept in tanks, the water is filtered via mechanical (solids removal) and biological (ammonia transformation to nitrate) mechanisms and dissolved oxygen is maintained, either via aeration or direct oxygen injection (Rakocy et al. 2006; Lennard 2017).

As has been argued in Sect. 5.0 (Introduction) of this chapter, historical examples of chinampas (Somerville et al. 2014) and Asian rice paddy farming (Halwart and Gupta 2004) as early iterations of aquaponics are unfounded and inappropriate examples of aquaponic principles, because modern aquaponics relies on designed additions of fish and fish feeds to supply a designed level of nutrition to the plants, and therefore, these historical examples cannot be considered in any way similar (Lennard 2017).

5.7 Nutrient Sources

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The major input to any aquaponic system are the nutrients added because aquaponic systems are designed to efficiently partition the nutrients added to them to the three important forms of life present: the fish and plants (which are the main products of the system) and the microflora (which assist to make the added nutrients available to the fish and plants) (Lennard 2017).

In classical, fully recirculating aquaponic designs, one of the key design drivers is to use the main nutrient input source, the fish feed, as efficiently as possible and therefore fully recirculating designs strive to supply as many of the nutrients required for the plants from the fish feed (Lennard 2017). Decoupled designs, on the other hand, place an emphasis on optimised plant growth by directly comparing the nutrient mixtures and strengths applied in standard hydroponics and substrate culture and trying to replicate those within the aquaponic context and therefore do not strive to supply as many of the nutrients required for the plants from the fish feed and utilise substantial external nutrient supplementations to achieve the required plant growth rates (Delaide et al. 2016). This means that a different emphasis is placed on the origin of the nutrients added, based on the technical design approach, and this, therefore, affects the main nutrient supply source of the aquaponic system; for fully recirculating designs, the major plant nutrient source is fish feed (via fish waste production), and for decoupled designs the major nutrient supply source for the plants is external supplements (e.g. nutrient salts) (Lennard 2017).

5.8 Aquaponics as an Ecological Approach

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Aquaponics, until recently, has been dominated by fully recirculating (or coupled) design approaches that share and recirculate the water resource constantly between the two major components (fish and plant culture) (Rakocy et al. 2006; Lennard 2017). In addition, the low to medium technology approaches historically applied to aquaponics have driven a desire to remove costly components so as to increase the potential of a positive economic outcome. One of the filtration components almost always applied to standard RAS and hydroponics/substrate culture technologies, that of aquatic sterilisation, has regularly not been included by aquaponic designers.

5.9 Advantages of Aquaponics

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Because there are two separate, existing, analogous technologies that produce fish and plants at high rates (RAS fish culture and hydroponic/substrate culture plant production), a reason for their integration seems pertinent. RAS produces fish at productive rates in terms of individual biomass gain, for the feed weight added, that rivals, if not betters, other aquaculture methods (Lennard 2017). In addition, the high fish densities that RAS allows lead to higher collective biomass gains (Rakocy et al. 2006; Lennard 2017). Hydroponics and substrate culture possess, within a controlled environment context, advanced production rates of plants that better most other agriculture and horticulture methods (Resh 2013). Therefore, initially, there is a requirement for aquaponics to produce fish and plants at rates that equal these two separate productive technologies; if not, then any loss of productive effort counts against any integration argument. If the productive rate of the fish and plants in an aquaponic system can equal, or better, the RAS and hydroponic industries, then a further case may be made for other advantages that may occur due to the integration process.

6.1 Introduction

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Recirculating water in the aquaculture portion of an aquaponics system contains both particulate and dissolved organic matter (POM, DOM) which enter the system primarily via fish feed; the portion of feed that is not eaten or metabolized by fish remains as waste in the recirculating aquaculture system (RAS) water, either in dissolved form (e.g. ammonia) or as suspended or settled solids (e.g. sludge). Once the majority of sludge is removed by mechanical separation, the remaining dissolved organic matter must still be removed from a RAS system. Such processes rely on microbiota in various biofilters in order to maintain water quality for the fish and to convert inorganic/organic wastes into forms of bioavailable nutrients for the plants. Microbial communities in aquaponics system include bacteria, archaea, fungi, viruses and protists in assemblages that fluctuate in composition based on an ebb and flow of nutrients and changes in environmental conditions such as pH, light and oxygen. Microbial communities play a significant role in denitrification and mineralization processes (see Chap. 10) and thus have key roles in the overall productivity of the system, including fish welfare and plant health.

6.2 Tools for Studying Microbial Communities

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New technologies for studying how microbial communities change over time, and which groups of organisms predominate under particular environmental conditions, have increasingly offered opportunities to anticipate adverse outcomes within system components and thus lead to the design of better sensors and tests for the effective monitoring of microbial communities in fish or plant cultures. For instance, various ‘omics’ technologies — metagenomics, metatranscriptomics, community proteomics, metabolomics — are increasingly enabling researchers to study the diversity of microbiota in RAS, biofilters, hydroponics and sludge digestor systems where sampling includes whole microbial assemblages instead of a given genome. Analysis of prokaryotic diversity in particular, has been helped enormously in recent decades by metagenomic and metatranscriptomic techniques. In particular, amplification and sequence analysis of the 16S rRNA gene, based on intraspecific conservation of neutral gene sequences flanking ribosomal operons in bacterial DNA, has been considered the ‘gold standard’ for taxonomic classification and identification of bacterial species. Such data is also used in microbiology to track epidemics and geographical distributions and study bacterial populations and phylogenies (Bouchet et al. 2008). The methodology can be labour-intensive and expensive, but recent automated systems, whilst not necessarily discriminatory at the species and strain level, offer opportunities for application in aquaponics settings (Schmautz et al. 2017). Recent reviews summarize applications of 16S rRNA as they pertain to RAS (Martínez-Porchas and Vargas-Albores 2017; Munguia-Fragozo et al. 2015; Rurangwa and Verdegem 2015). Advances in metagenomics of microbes other than bacteria found in RAS and hydroponics rely on similar methodologies but use 18S (eukaryotes), 26S (fungi) and 16S in combination with 26S (yeasts) rRNA clone libraries to characterize these microbiota (Martínez-Porchas and VargasAlbores 2017). Detailed rRNA libraries, for instance, have also been used in hydroponics to characterize microbial communities in the rhizosphere (Oburger and Schmidt 2016). Such libraries can be particularly useful in aquaponics, given that they can examine assemblage of microorganisms such as bacteria, archaea, protozoans and fungi and provide feedback on changes within the system.

6.3 Biosecurity Considerations for Food Safety and Pathogen Control

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6.3.1 Food Safety

Good food safety and ensuring animal welfare are high priorities in gaining public support for aquaponics. One of the most frequent issues raised by food safety experts in relation to aquaponics is the potential risk of contamination with human pathogens when using fish effluent as fertilizer for plants (Chalmers 2004; Schmautz et al. 2017). A recent literature search to determine zoonotic risks in aquaponics concluded that pathogens in contaminated intake water, or pathogens in components of feeds originating with warm-blooded animals, can become associated with fish gut microbiota, which, even if not detrimental to the fish themselves, can potentially be passed up the food chain to humans (Antaki and Jay-Russell 2015). The mechanisms of introduction of pathogens to an aquaponics system are thus of concern, with the likeliest source of faecal coliforms or other pathogenic bacteria stemming from feed inputs to fish. From a biological perspective, there are potential risks of these pathogens proliferating either in biofilters, or, in one-loop systems by introducing airborne pathogens from open plant components back to the fish tanks. Although biosecurity risks are low in the relatively closed environmental space of an aquaponics system — as compared for instance to open pond aquaculture — and are even lower in decoupled aquaponics system wherein portions of the system can be isolated, there is still a perception that fish sludge could be potentially dangerous when applied to plants for human consumption. Escherichia coli (E. coli) is a human enteric pathogen causing foodborne illnesses that has been a key concern regarding the use of animal waste as fertilizer in agriculture or aquaculture, e.g. integrated pig-fish systems (Dang and Dalsgaard 2012). However, it is generally not considered to present a risk in fish-plant aquaponics. For instance, Moriarty et al. (2018) previously demonstrated that UV-radiation treatment can successfully reduce E. coli but also noted that the coliforms detected in the aquaponics system were at background levels and did not proliferate in the fish raceways or in the hydroponically grown lettuce within the experimental system, and thus did not present a health risk. There is limited research on these aspects, but a few preliminary studies have found very low risks of coliform contamination, for instance, by showing no difference in coliform levels from sterilized and non-sterilized RAS water treatments applied to plants (Pantanella et al. 2015). Even though there is a potential risk of internalization of microbes within plant leaves, and thus their transmission to the consumed portions of some edible leafy plants grown in aquaponics, other studies have come to similar conclusions that the risks are minimal of introducing potentially dangerous human pathogens (Elumalai et al. 2017).

6.4 Microbial Equilibrium and Enhancement in Aquaponics Units

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Productivity in aquaponics system involves monitoring and managing environmental parameters in order to provide each component, whether microbial, animal or plant, with optimal growth conditions. Whilst this is not always possible given tradeoffs in requirements, one of the key goals of aquaponics revolves around the concept of homeostasis, wherein maintaining stability of the system involves adjusting operational parameters to minimize unnecessary perturbations that cause stress within a unit, or detrimental effects on other components. With ever-changing microbial assemblages, homeostasis never implies a permanent state of equilibrium, but rather a goal of achieving as much stability as possible, particularly within water quality parameters.

6.5 Bacterial Roles in Nutrient Cycling and Bioavailability

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Considerable research has been conducted to characterize heterotrophic and autotrophic bacteria in RAS systems and to better understand their roles in maintaining water quality and cycling of nutrients (for reviews, see Blancheton et al. (2013); Schreier et al. (2010). Non-pathogenic heterotrophs, typically dominated by Alphaproteobacteria and Gammaproteobacteria, tend to thrive in biofilters, and their contributions to transformations of nitrogen are fairly well understood because nitrogen cycling (NC) has been of paramount importance in developing recirculating culture systems (Timmons and Ebeling 2013). It has long been recognized that the bacterial transformation of the ammonia excreted by fish in a RAS system must be matched with excretion rates, because excess ammonia quickly becomes toxic for fish (see Chap. 9). Therefore in freshwater and marine RAS, the functional roles of microbial communities in NC dynamics — nitrification, denitrification, ammonification, anaerobic ammonium oxidation and dissimilatory nitrate reduction — have received considerable research attention and are well described in recent reviews (Rurangwa and Verdegem 2015; Schreier et al. 2010). There are far fewer studies of nitrogen transformations in aquaponics, but a recent review (Wongkiew et al. 2017) provides a summary along with discussion of nitrogen utilization efficiency, which is a prime consideration for plant growth in hydroponics.

6.6 Suspended Solids and Sludge

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The parameters for operating aquaponics at a given scale — including water volume, temperature, feed and flow rates, pH, fish and crop ages and densities — all affect the temporal and spatial distribution of the microbial communities that develop within its compartments, for reviews: RAS (Blancheton et al. 2013); hydroponics (Lee and Lee 2015).

In addition to controlling dissolved oxygen, carbon dioxide levels and pH in aquaponics, it is also essential to control the accumulation of solids in the RAS system as fine suspended particles can adhere to gills, cause abrasion and respiratory distress and increase susceptibility to disease (Yildiz et al. 2017). More relevant, the particulate organic matter (POM) must be quickly and effectively removed from RAS systems, or else excessive heterotrophic growth will cause almost all unit processes to fail. RAS feeding rates must be carefully managed to minimize solids loading on the system (e.g. avoid over-feeding and minimize feeding costs). The biophysical properties of feed — particle size, nutrient content, digestibility, sensory appeal, density and settling rate — determine ingestion and assimilation rates, which in turn have an impact on solids build-up and thus water quality. Although water quality is frequently studied in the context of nutrient cycling (see Chap. 9), it is also important to obtain a better understanding of the composition of microbial communities and changes in these based on feed composition, particulate loading and how this influences the growth of heterotrophic and autotrophic bacterial communities.

6.7 Conclusions

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Formerly the domain of small-scale producers, technological advances are increasingly moving aquaponics into larger-scale commercial production by focusing on improved macro- and micronutrient recovery whilst providing technical innovations to reduce water and energy requirements. However, scaling up of aquaponics to an industrial scale requires a much better understanding and maintenance of microbial assemblages, and the implementation of strong biocontrol measures that favour the health and well-being of both fish and crops, whilst still meeting food safety standards for human consumption. Further research on biocontrol of microbial pathogens in aquaponics, including potential human, fish and plant pathogens are needed, in light of the sensitivity of such systems to perturbation, and the fact that the use of chemicals and antibiotics can have profound effects on microbial populations, fish and plant physiologies, as well as overall system operation. Elucidating microbial interactions can improve the productivity of aquaponics system given the crucial roles of microbes in converting organic matter into usable forms that can allow fish and plants to thrive.

7.1 Introduction

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Fig. 7.1 Diagram of the first system by Naegel (1977) growing Tilapia and common carp in combination with lettuce and tomatoes in a closed recirculation system

The combination of fish and plant cultivation in coupled aquaponics dates back to the first design by Naegel (1977) in Germany, using a 2000 L hobby scale system (Fig. 7.1) located in a controlled environment greenhouse. This system was developed in order to verify the use of nutrients from fish waste water under fully controlled water recirculating conditions intended for plant production including a dual sludge system (aerobic/anaerobic wastewater treatment). Naegel based his concept on the open pond aquaponic system of the South Carolina Agricultural Experiment Station, in the USA, where excess nutrients from the fishponds, stocked with channel catfish (Ictalurus punctatus), were eliminated by the hydroponic production of water chestnuts (Eleocharis dulcis) (Loyacano and Grosvenor 1973). By including nitrification and denitrification tanks to increase the nitrate concentration inside his system, Naegel (1977) attempted a complete oxidation of all nitrogenous compounds, reaching nitrate concentrations of 1200 mg/L, and demonstrating the effectiveness of the nitrification step. Although the system was stocked at a low density (20 kg/msup3/sup each) using tilapia (Tilapia mossambica) and carp (Cyprinus carpio), the tomatoes (Lycopersicon esculentum) and iceberg lettuce (Lactuca scariola) grew well and produced harvestable yield. These first research results led to the concept of coupled aquaponic systems, in which the plants eliminate the waste produced by the fish, creating adequate growth, demonstrating highly efficient water use in both units. The principle of coupled aquaponics was first described by Huy Tran at the World Aquaculture Conference in 2015 (Tran 2015).

7.2 Historical Development of Coupled Aquaponics

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Most original research efforts on coupled aquaponic systems took place in the USA with an increasing presence in the EU partly initiated by COST Action FA1305, The EU Aquaponics Hub and in other European research centres. Nowadays, fully recirculating aquaponic system designs almost completely dominate the American aquaponics industry, with estimates that over 90% of the existing aquaponic systems in the USA are of a fully recirculating design (Lennard, pers. comm.). The first American coupled aquaponics research was undertaken at the Illinois Fisheries and Aquaculture Center (formerly the SIU Cooperative Fisheries Research Laboratory) and the Department of Zoology, focusing on coupled aquaponic systems stocked with channel catfish (Ictalurus punctatus) in combination with tomatoes (Lycopersicon esculentum) (Lewis et al. 1978). The authors noted that an optimal plant growth is only possible when all the essential macro- and micronutrients are available in the process water, and thus nutrient supplementation is required in the event of nutrient deficiencies. The authors also demonstrated a deficiency in plant-available iron, constraining plant growth, which could be solved through ironchelate supplementation. Other early studies in the USA focused on analysing technological functionality and the quality of the harvested channel catfish and tomatoes (Lewis et al. 1978; Sutton and Lewis 1982). Laboratory-scale aquaponic systems examined parameters, such as resource efficiencies with regard to materials, costs, water and energy consumption, and examined the use of other fish species such as Tilapia spp. in the US Virgin Islands (UVI) (Watten and Busch 1984). Dr. James Rakocy at the UVI developed the first commercial coupled aquaponic system, a raft system that combined the production of Nile Tilapia (Oreochromis niloticus) and lettuce (Lactuca sativa), and later investigated the production of further plant species (Rakocy 1989, 2012; Rakocy et al. 2000, 2003, 2004, 2006, 2011). This medium scale commercial installation took advantage of the local climate where greenhouses were not necessary and the market conditions of the Virgin Islands to generate profit. The UVI aquaponic system was subsequently adopted in different countries with respect to the respective needs of different plants and the appropriateness of the technology, e.g. in Canada by Savidov (2005) and in Saudi Arabia by Al-Hafedh et al. (2008). This is the case in Europe as well, where coupled aquaponic systems have evolved from the original UVI design, e.g. the vertical aquaponic system at the Aquaponics Research Lab., University of Greenwich (Khandaker and Kotzen 2018). Several other research departments investigated the technological feasibility of closed — or ‘coupled’ — aquaponics production using various fish and plant species as well as hydroponic subsystems to increase yields and reducing different emission parameters (Graber and Junge 2009). For example, at Rostock University (Germany), the research focused on the stability of backyard systems (Palm et al. 2014a), combining different fish species, African catfish (Clarias gariepinus) and Nile tilapia (Oreochromis niloticus), with different plants (Palm et al. 2014b, 2015). In 2015, a modern experimental semi-commercial scale aquaponic system, the ‘FishGlassHouse’, was built on the campus of the University of Rostock (Palm et al. 2016). However, the system was designed allowing both coupled and decoupled operations. Other notable facilities were built at the Zürich University of Applied Sciences (ZHAW) at Waedenswil in Switzerland (Graber and Junge 2009; Graber et al. 2014), both coupled and decoupled research facility of the Icelandic company Svinna-verkfraedi Ltd. (Thorarinsdottir 2014; Thorarinsdottir et al. 2015), the cold water aquaponic system NIBIO Landvik at Grimstad (Skar et al. 2015; Thorarinsdottir et al. 2015), the PAFF Box (Plant And Fish Farming Box) one loop aquaponic system at Gembloux Agro-Bio Tech University of Liège, in Gembloux, Belgium (Delaide et al. 2017), the combined living wall and vertical farming aquaponic system at the University of Greenwich (Khandaker and Kotzen 2018), as well as the research-domestic coupled aquaponic system (changed from decoupled to coupled in 2018, Morgenstern and Dapprich 2018, pers. comm.) at the South Westphalia University of Applied Sciences, i.GREEN Institute for Green Technology & Rural Development.

7.3 Coupled Aquaponics: General System Design

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The coupled aquaponics principle combines three classes of organisms: (1) aquatic organisms, (2) bacteria and (3) plants that benefit from each other in a closed recirculated water body. The water serves as a medium of nutrient transport, mainly from dissolved fish waste, which is converted into nutrients for plant growth by bacteria. These bacteria (e.g. Nitrosomonas spec., Nitrobacter spec.) oxidize ammonium to nitrite and finally to nitrate. Therefore, it is necessary for the bacteria to receive substantial amounts of ammonium and nitrite to stabilize colony growth and the quantity of nitrate production. Consequently, in a coupled aquaponic system, volumes are critically important, i) the aquaculture unit following the principles of recirculating aquaculture systems (RAS), ii) the bacterial growth substrate and iii) the space for the plant units and the amount of plants to be cultivated. Together, they form the aquaponics unit (Fig. 7.2).

7.4 Aquaculture Unit

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The fish-rearing tanks (size, numbers and design) are selected depending on the scale of production and fish species in use. Rakocy et al. (2006) used four large fishrearing tanks for the commercial production of O. niloticus in the UVI aquaponic system (USA). With the production of omnivorous or piscivorous fish species, such as C. gariepinus, several tanks should be used due to the sorting of the size classes and staggered production (Palm et al. 2016). Fish tanks should be designed so that the solids that settle at the bottom of the tanks can effectively be removed through an effluent at the bottom. This solid waste removal is the first crucial water treatment step in coupled aquaponics as is the case in aquaculture and decoupled aquaponics. The waste originates from uneaten feed, fish faeces, bacterial biomass and flocculants produced during aquaculture production, increasing BOD and reducing water quality and oxygen availability with respect to both the aquaculture and hydroponic units. In aquaculture, the solid waste consists to a large extent of organic carbon, which is used by heterotrophic bacteria to produce energy through oxygen consumption. The better the solid waste removal, the better the general performance of the system for both fish and plants, i.e. with optimal oxygenation levels and no accumulation of particles in the rhizosphere inhibiting nutrient uptake, and with round or oval tanks proving to be particularly efficient (Knaus et al. 2015).

7.5 Scaling Coupled Aquaponic Systems

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Typical coupled aquaponic system range from small to medium scale and larger sized systems (Palm et al. 2018). Upscaling remains one of the future challenges because it requires careful testing of the possible fish and plant combinations. Optimal unit sizes can be repeated to form multiunit systems, independent of the scale of production. According to Palm et al. (2018), the range of aquaponic systems were categorized into (1) mini, (2) hobby, (3) domestic and backyard, (4) small/ semi-commercial and (5) large(r)-scale systems, as described below:

7.6 Saline/Brackish Water Aquaponics

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A relatively new field of research is the evaluation of different salinities of the process water for plant growth. Since freshwater worldwide is in continuously increasing demand and at high prices, some attention has been given to the use of saline/brackish water resources for agriculture, aquaculture and also aquaponics. The use of brackish water is significant as many countries such as Israel have underground brackish water resources, and more than half the world’s underground water is saline. Whilst the amount of underground saline water is only estimated as 0.93% of world’s total water resources at 12,870,000 kmsup3/sup, this is more than the underground freshwater reserves (10,530,000 kmsup3/sup), which makes up 30.1% of all freshwater reserves (USGS).

7.7 Fish and Plant Choices

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7.7.1 Fish Production

In larger scale commercial aquaponics fish and plant production need to meet market demands. Fish production allows species variation, according to the respective system design and local markets. Fish choice also depends on their impact onto the system. Problematic coupled aquaponics fish production due to inadequate nutrient concentrations, negatively affecting fish health, can be avoided. If coupled aquaponic systems have balanced fish to plant ratios, toxic nutrients will be absorbed by the plants that are cleaning the water. Since acceptance of toxic substances is species dependent, fish species choice has a decisive influence on the economic success. Therefore, it is important to find the right combination and ratio between the fish and the plants, especially of those fish species with less water polluting activities and plants with high nutrient retention capacity.

7.8 System Planning and Management Issues

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Coupled aquaponics depends on the nutrients that are provided from the fish units, either a commercial intensive RAS or tanks stocked under extensive conditions in smaller operations. The fish density in the latter is often about 15—20 kg/msup3/sup (tilapia, carp), but extensive African catfish production can be higher up to 50 kg/msup3/sup. Such different stocking densities have a significant influence on nutrient fluxes and nutrient availability for the plants, the requirement of water quality control and adjustment as well as appropriate management practices.

7.9 Some Advantages and Disadvantages of Coupled Aquaponics

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The following discussion reveals a number of key pros and challenges of coupled aquaponics as follows:

Pro: Coupled aquaponic systems have many food production benefits, especially saving resources under different production scales and over a wide range of geographical regions. The main purpose of this production principle is the most efficient and sustainable use of scarce resources such as feed, water, phosphorous as a limited plant nutrient and energy. Whilst, aquaculture and hydroponics (as stand-alone), in comparison to aquaponics are more competitive, coupled aquaponics may have the edge in terms of sustainability and thus a justification of these systems especially when seen in the context of, for example, climate change, diminishing resources, scenarios that might change our vision of sustainable agriculture in future.

8.1 Introduction

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As discussed in Chaps. 5 and 7, single-loop aquaponics systems are well-researched, but such systems have a suboptimal overall efficiency (Goddek et al. 2016; Goddek and Keesman 2018). As aquaponics scales up to industrial-level production, there has been emphasis on increasing the economic viability of such systems. One of the best opportunities to optimize production in terms of harvest yield can be accomplished by uncoupling the components within an aquaponics system to ensure optimal growth conditions for both fish and plants. Decoupled systems differ from coupled systems insomuch as they separate the water and nutrient loops of both the aquaculture and hydroponics unit from each another and thus provide a control of the water chemistry in both systems. Figure 8.1 provides a schematic overview of a traditional coupled system (A), a decoupled two-loop system (B), and a decoupled multi-loop system (C). However, there is considerable debate whether decoupled aquaponics systems are economically advantageous over more traditional systems, given that they require more infrastructure. In order to answer that question, it is necessary to consider different system designs in order to identify their strengths and weaknesses.

8.2 Mineralization Loop

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In RAS, solid and nutrient-rich sludge must be removed from the system to maintain water quality. By adding an additional sludge recycling loop, accumulating RAS wastes can be converted into dissolved nutrients for reuse by plants rather than discarded (Emerenciano et al. 2017). Within bioreactors, microorganisms can break down this sludge into bioavailable nutrients, which can subsequently be delivered to plants (Delaide et al. 2018; Goddek et al. 2018; Monsees et al. 2017a, b). Many one-loop aquaponics systems already include aerobic (Rakocy et al. 2004) and anaerobic (Yogev et al. 2016) digesters to transform nutrients that are trapped in the fish sludge and make them bioavailable for plants. However, integrating such a system into a coupled one-loop aquaponics system has several disadvantages:

8.3 Distillation/Desalination Loop

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In decoupled aquaponics systems, there is a one-way flow from the RAS to the hydroponics unit. In practice, plants take up water supplied by RAS, which in turn is topped up with fresh (i.e. tap or rain) water. The necessary outflow from the RAS unit is equal to the difference between the water leaving the HP system via plants (and via the distillation unit) and the water entering the hydroponics unit from the mineralization reactor, if the system includes a reactor (Fig. 8.4). A simplified summary is that the long-term water flux requirement from RAS to HP is equal to the crop water consumption by evapotranspiration and plant water storage in the plant biomass.

8.4 Sizing Multi-loop Systems

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Sizing an aquaponics system requires balancing the nutrient input and -output. Here, we basically apply the same principle as sizing a one-loop system. Yet, this approach is a bit more complicated, but will be fully illustrated with the aid of an example.

Fig. 8.5 Scheme that shows the mass balance within a four-loop aquaponics system; where msubfeed/sub are the dissolved nutrients added to the system via feed. Add labels: QsubDIS/sub - QsubX/sub to distillate returned to HP; ‘sludge’ for nutrients entering reactor

8.5 Monitoring and Control

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In classical feedback control, like PI or PID (Proportional-Integral-Derivative) control, the controlled variables (CV) are directly measured, compared with a setpoint, and subsequently fed back to the process via a feedback control law.

In Fig. 8.10, the signals, without the time argument, are denoted by a small letter, where y is the controlled variable (CV) which is compared with the reference (setpoint) signal r. The tracking error ε (i.e. r - y) is fed into the controller, either in hardware or software, from which the control input u, also known as the manipulated variable (MV), is generated. The input u directly affects the process (P) from which an output (y) results. The sampled output is subsequently compared with r, which closes the loop. In practice, this loop continues until the controller is switch off. There exists extensive literature on feedback control (Doyle et al. 1992; Morris 2001; Ogata 2010), and this has been a subject of research for many years, starting with the works of Bode (1930) and Nyquist (1932).

8.6 Economic Impact

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Technologies that generate less profit, but are better for the environment usually only get implemented when the operators either receive an incentive in the form of subsidies or policies force them to do so. In the case of one-loop aquaponics systems, the appeal lies in the novel technology and the system’s approach to sustainable resource use rather than its economic potential. However, recent publications provide evidence for production gains: leafy greens grow better in decoupled environments than in sterile hydroponic systems (Delaide et al. 2016; Goddek and Vermeulen 2018) and lettuce in decoupled aquaponics systems had a growth advantage of approximately 40% compared to state-of-the-art hydroponic approaches.

8.7 Environmental Impact

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Based on Example 8.2, there is evidence that treating sludge in digesters can have a beneficial impact on nutrient reutilization, especially phosphorus. Bioreactor systems, such as a sequential two-stage UASB reactor system, can increase the phosphorus recycling efficiency up to 300% (Chap. 10). Previously, in Chap. 2, we discussed the phosphorus paradox in relation to both phosphate scarcity and problems with eutrophication. Bioreactors have significant advantages for increased nutrient recovery from sludge, thus helping to close the nutrient cycling loop within aquaponics systems. However, further research is needed to refine such systems to optimize the bioavailability of specific nutrients. Figures 8.11, 8.12, and 8.13 show the input, output, and waste streams of stand-alone aquaculture and hydroponics systems compared with a decoupled aquaponics system. It can be seen that the decoupled approach constitutes a promising agricultural concept for a waste reduction and recycling system.

9.1 Introduction

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Aquaponic systems offer various advantages when it comes to producing food in an innovative and sustainable way. Besides the synergistic effects of increased aerial COsub2/sub concentration for greenhouse crops and decreased total heat energy consumption when cultivating fish and crops in the same space (Körner et al. 2017), aquaponics has two main advantages for nutrient cycling. First, the combination of a recirculating aquaculture system with hydroponic production avoids the discharge of aquaculture effluents enriched in dissolved nitrogen and phosphorus into already polluted groundwater (Buzby and Lin 2014; Guangzhi 2001; van Rijn 2013), and second, it allows for the fertilisation of the soilless crops with what can be considered an organic solution (Goddek et al. 2015; Schneider et al. 2004; Yogev et al. 2016) instead of using fertilisers of mineral origin made from depleting natural resources (Schmautz et al. 2016; Chap. 2). Furthermore, aquaponics yields comparable plant growth as compared with conventional hydroponics despite the lower concentrations of most nutrients in the aquaculture water (Graber and Junge 2009; Bittsanszky et al. 2016; Delaide et al. 2016), and production can be even better than in soil (Rakocy et al. 2004). Increased COsub2/sub concentrations in the aerial environment and changes in the biomes of the root zone are thought to be main reasons for this. In addition, the mineral content and the nutritional quality of tomatoes grown aquaponically have been reported to be equivalent or superior to the mineral content of conventionally grown ones (Schmautz et al. 2016).

9.2 Origin of Nutrients

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The major sources of nutrients in an aquaponic system are the fish feed and the water added (containing Mg, Ca, S) (see Sect. 9.3.2.) into the system (Delaide et al. 2017; Schmautz et al. 2016) as further elaborated in Chap. 13. With respect to fish feed, there are two main types: fishmeal-based and plant-based feed. Fishmeal is the classic type of feed used in aquaculture where lipids and proteins rely on fish meal and fish oil (Geay et al. 2011). However, for some time now, concerns regarding the sustainability of such feed have been raised and attention drawn towards plant-based diets (Boyd 2015; Davidson et al. 2013; Hua and Bureau 2012; Tacon and Metian 2008). A meta-analysis conducted by Hua and Bureau (2012) revealed that the use of plant proteins in fish feed can influence the growth of fish if incorporated in high proportions. Indeed, plant proteins can have an impact on the digestibility and levels of anti-nutritional factors of the feed. In particular, phosphorus originating from plants and thus in the form of phytates does not benefit, for example, salmon, trout and several other fish species (Timmons and Ebeling 2013). It is not surprising that this observation is highly dependent on the fish species and on the quality of the ingredients (Hua and Bureau 2012). However, little is known of the impact of varying fish feed composition on crop yields (Yildiz et al. 2017).

9.3 Microbiological Processes

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9.3.1 Solubilisation

Solubilisation consists of the breaking down of the complex organic molecules composing fish waste and feed leftovers into nutrients in the form of ionic minerals which plants can absorb (Goddek et al. 2015; Somerville et al. 2014). In both aquaculture (Sugita et al. 2005; Turcios and Papenbrock 2014) and aquaponics, solubilisation is conducted mainly by heterotrophic bacteria (van Rijn 2013; Chap. 6) which have not yet been fully identified (Goddek et al. 2015). Some studies have started deciphering the complexity of these bacteria communities (Schmautz et al. 2017). In current aquaculture, the most commonly observed bacteria are Rhizobium sp., Flavobacterium sp., Sphingobacterium sp., Comamonas sp., Acinetobacter sp., Aeromonas sp. and Pseudomonas sp. (Munguia-Fragozo et al. 2015; Sugita et al. 2005). An example of the major role of bacteria in aquaponics could be the transformation of insoluble phytates into phosphorus (P) made available for plant uptake through the production of phytases which are particularly present in γ-proteobacteria (Jorquera et al. 2008). (More research needs to be done in this area). Other nutrients than P can also be trapped as solids and evacuated from the system with the sludge. Efforts are thus being made to remineralise this sludge with UASB-EGSB reactors in order to reinject nutrients into the aquaponic system (Delaide 2017; Goddek et al. 2016; Chap. 10). Furthermore, different minerals are not released at the same rate, depending on the composition of the feed (LetelierGordo et al. 2015), thus leading to more complicated monitoring of their concentration in the aquaponic solution (Seawright et al. 1998).

9.4 Mass Balance: What Happens to Nutrients once They Enter into the Aquaponic System?

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9.4.1 Context

The functioning of aquaponic systems is based on a dynamic equilibrium of the nutrient cycles (Somerville et al. 2014). It is therefore necessary to understand these cycles in order to optimise the management of the systems. Plants growing hydroponically have specific requirements, which should be met during their various growing stages (Resh 2013). Therefore, nutrient concentrations in the different compartments of the system must be closely monitored, and nutrients should be supplemented to prevent deficiencies (Resh 2013; Seawright et al. 1998) either in the system water or via foliar application (Roosta and Hamidpour 2011).

9.5 Conclusions

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9.5.1 Current Drawbacks of Nutrient Cycling in Aquaponics

In hydroponics, the nutrient solution is accurately determined and the nutrient input into the system is well understood and controlled. This makes it relatively easy to adapt the nutrient solution for each plant species and for each growth stage. In aquaponics, according to the definition (Palm et al. 2018), the nutrients have to originate at least at 50% from uneaten fish feed, fish solid faeces and fish soluble excretions, thus making the monitoring of the nutrient concentrations available for plant uptake more difficult. A second drawback is the loss of nutrients through several pathways such as sludge removal, water renewal or denitrification. Sludge removal induces a loss of nutrients as several key nutrients such as phosphorus often precipitate and are then trapped in the evacuated solid sludge. Water renewal, which has to take place even if in small proportions, also adds to the loss of nutrients from the aquaponic circuit. Finally, denitrification happens because of the presence of denitrifying bacteria and conditions favourable to their metabolisms.

Aquaponics in the Age of the Coronavirus Quarantine

Mon, 16 Mar 2020 00:00:00 +0000

Get invested in Aquaponics so you can relax and be free from complex supply chain stressors and enjoy your own backyard meal in the age of the COVID-19.

My name is Jonathan Reyes and I am a co-founder of FarmHub and Tulua. These two companies, on two separate continents, are doubling down on the power and essential nature of Aquaponics. So when I tell you Aquaponics is absolutely the way to regeneratively farming your future, you can trust I’m not just saying it for kicks.

Sourcing and Managing Your Fish Feed in Aquaculture Systems

Thu, 20 Feb 2020 00:00:00 +0000

In the aquaculture industry, 60-70% of the production cost comes from fish feeds; therefore, choosing a commercial feed for cultured fish must not be taken for granted.

Nutrient Requirements

The nutrient requirement of the fish to be fed must be known first and should be comparable with the nutritional value of the feed. Note that some fish may differ in their nutrient requirements in some areas of their life stages.

Introducing Fish into Your Aquaponic System with a Salt Bath

Fri, 14 Feb 2020 00:00:00 +0000

Minerals found in water environment plays important roles in physiological functions in fish. In aquaculture production, salt which is a mineral in the form of sodium chloride (NaCl) has many positive applications. The raw material is affordable and available to many fish farmers. Salt bath is one significant application being practiced in the fish production industry. It is an immersion process of freshwater fish to salt solution at a prolonged time. This practice is usually done for the newly arrived fish stocks. The effectivity of this process could be influenced by the salt concentration, time of exposure and the fish species.

Accurately Sizing an Aquaponics System Pump

Thu, 07 Nov 2019 00:00:00 +0000

A water pump is the primary life source for an Aquaponics system. This decision deserves attention and research. A bad choice can keep you purchasing new pumps every few months or not delivering enough water turnover for your fish.

There is a comprehensive water pump flow rate generator that will get you half way there by calculating the liters/gallons per hour needed. You only need to know how many Media Beds and DWC taps you have in your system, and how much water is in your fish tank. The next decision is quality, type, brand, and submersible, in-line or air.

Properly Sourcing Your IBC Totes in a Country Without Amazon Prime

Sat, 26 Oct 2019 00:00:00 +0000

If you’re fortunate enough to live in a country that has a vendor that can deliver cheap, sparkling new IBC totes, congratulations you just finished sourcing and cleaning them. For the rest of us, this is just the beginning. Read on.

IBC Totes have some serious stories to tell. I have seen IBC totes come from all over the place. They travel on barges, trucks, wagons, cars, and get dumped, thrown, melted, burned, and who knows what else. That IBC tote, and its wonderful secrets, could probably sitting in your Aquaponics system.

Never Suffer From Cutting IBC Totes Again

Fri, 04 Oct 2019 00:00:00 +0000

Once you have sourced your IBC totes, cleaned them well, it’s time to begin cutting them and preparing them to be fish tanks, sump tanks, or even distribution tanks. You can also cut them in half and use them as a sump tank or a growbed, but we’re going to focus on the other purposes as it requires a different cut.

To keep your totes functioning well and in good condition, you’ll need to take care of the structural integrity. The structure itself is made for shipping liquid material so you’re not wrong to use them for water. However, there is a better way to cut the tanks.

Managing Algae Growth in Aquaponic Systems

Sat, 07 Sep 2019 00:00:00 +0000

Algae is part of earth’s amazing biosphere that we get to manage in an Aquaponics system. It’s not a bad thing that you have algae in your system, but it can certainly cause some difficult problems if not monitored.

While algae is natural, a large amount is undesirable in an Aquaponics system. You will encounter some serious issues if your algae gets out of hand:

Dissolved Oxygen Depletion

Dissolved oxygen in your system is one of the life sources for your plants and fish. Algae will consume this dissolved oxygen and leave very little for your fish and plants.

Growing Crops in the Desert

Tue, 25 Sep 2018 00:00:00 +0000

We are entering a new era where farming techniques and laborious tasks can be greatly improved and enhanced with the help of necessary technology. Aquaponics helps farmers save costs, increase yield, and even improve health and sustainability of the farm itself. Not only that, but anyone can do it!

One of the many fascinating aspect of aquaponics farming is the ability to control environmental and other climatic conditions. It can be adjusted to suit the optimum plant growing conditions. The integration of a successful aquaponics system in the deserts is possible, and several companies have been involved in establishing aquaponics agriculture and being made sustainable. One of the world’s largest aquaponics farm with hundreds of tilapia spp fish and a fish tank filled with tea-brown water has been successfully built by Jabber Al Mazroui in the United Arab Emirates.

Growing with Aquaponics

Mon, 25 Jun 2018 00:00:00 +0000

An Aquaponics system is a combination of aquaculture (fish farming) and hydroponics (the medium of cultivating plants without soil media). The technology of aquaponics works together in a way that both the plants and the fishes cultivated have a mutually beneficial relationship as there is a recycling of nutrients occurring between them. This is nothing new to the Middle East and actually uses technology that the Ancient Egyptians invented over 10,000 years ago. It is built around the idea that microbes disintegrate fish wastes into nutritional supplements and provide the plants with food and the fish with clean water. The presence of microbes keeps the aquaponic system active.

Fresh Technology, New Humanity

Tue, 24 Apr 2018 00:00:00 +0000

It’s so easy to focus on the negative impacts of environmental decline. The statistics themselves could make you fear your children’s future. However, that doesn’t do anyone any good. Taking the fear approach to future only creates a future founded on fear. Instead, I invite you into something greater…

Today I speak to you, the Arab world, and invite you into a new journey, a new place to look at how life, technology and connectivity are all interrelated. You have a unique perspective on life, community, and family and the world wants to experience the passions of these cultural values.

Hydroponic Solutions in Middle Eastern Contexts

Sun, 15 Apr 2018 00:00:00 +0000

One major challenge facing the world’s agricultural sector in both crop and livestock production is the threat of global climate change resulting in arid and desert lands in some regions of the world. An area is considered as a desert when there is a low precipitation period below 10 inches in a particular geographical region caused by prolonged water supply shortages. Agricultural activities in crop production for humans and fodder supplies from crop residues for livestock rearing is at declining state in crop production.