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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).
In Europe, the early RAS date back to the late 1970s (Bohl 1977). At the same time Naegel (1977) had already tested the integration of hydroponics with the water and nutrient cycles of RAS. Contemporary aquaponics in the USA started with the pioneering research of Todd, as referred to in Love et al. (2014), together with studies by Goldman et al. 1974 and Ryther et al. 1975 of the reuse of nutrients from wastewater for plant and animal production. 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. The pioneers of aquaponics who inspired many followers were:
Dr Mark McMurtry (McMurtry et al. 1990) began working on aquaponics when he was at North Carolina State University in the mid-eighties to early nineties. He called the method ‘Integrated AquaVegeculture System’ (IAVS). Today’s flood-and-drain systems, as favoured by backyard practitioners, are derived from this model.
Dr James Rakocy designed what is perhaps the most widely copied design, The University of Virgin Islands (UVI) Aquaponic system in 1980 (Rakocy et al. 2003; Rakocy et al. 2004). He has developed vital ratios and calculations in order to maximize production of both fish and vegetables while maintaining a balanced ecosystem.
In Canada, Dr Nick Savidov (Savidov & Brooks 2004) showed that, when some key nutrients levels were met, aquaponic systems had significantly superior production of tomatoes and cucumbers when compared with hydroponic systems.
These research breakthroughs, as well as many others, have paved the way for various practitioner groups and companies that are beginning to sprout worldwide. However, aquaponics research really took off only after 2010 (see the comparative number of scientific publications on hydroponics, aquaculture, and aquaponics in Figure 10). There is, however, a big difference between what the world is ‘talking’ about, and what is being currently researched. Junge et al. (2017) coined the term 'hype ratio' as an indicator of the popularity of a subject in the public media compared with academia. It is calculated as search results in Google divided by search results in Google Scholar. Aquaponics has a 'hype ratio' of over 1000, which is significantly higher than, for example hydroponics (over 100) and aquaculture (about 20). In this regard, aquaponics can be termed 'an emerging technology' and an emerging science topic.
Figure 10: The number of papers published on hydroponic*, aquaculture*, and aquaponic*‡ from 1978 to 2015 (data were collected from the Scopus database on 17 September 2016). ‡ Please note that the scale for aquaponic* is two orders of magnitude lower than hydroponic* or aquaculture* (from Junge et al. 2017).
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