AQUAPONIC TECHNOLOGY
Introduction to aquaponic technology
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.
· Aqu@teachHistory of aquaponics
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).
· Aqu@teachExamples of aquaponic systems around the world
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.
· Aqu@teachElements of aquaponic systems
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.
· Aqu@teachCurrent research themes in aquaponics
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.
· Aqu@teachClassification of aquaponics
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.
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