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Balancing the aquaponic ecosystem
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.
· Food and Agriculture Organization of the United NationsAquaponics
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.
· Food and Agriculture Organization of the United NationsAquaculture
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.
· Food and Agriculture Organization of the United NationsApplicability of aquaponics
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.
· Food and Agriculture Organization of the United NationsAcclimatizing fish
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.
· Food and Agriculture Organization of the United NationsA brief history of modern aquaponic technology
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.
· Food and Agriculture Organization of the United Nations9.5 Conclusions
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.
· Aquaponics Food Production Systems9.4 Mass Balance: What Happens to Nutrients once They Enter into the Aquaponic System?
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.
· Aquaponics Food Production Systems9.3 Microbiological Processes
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.
· Aquaponics Food Production Systems9.2 Origin of Nutrients
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.
· Aquaponics Food Production Systems