5.1 Introduction
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).
An interesting additional advantage of integrating aquaculture with the irrigation supply pathway for plant production is that aquaculture also produces waste nutrients via the dissolved and undissolved wastes produced from fish (and other aquatic animal) metabolism. Therefore, aquaculture may also produce waste nutrient streams that are suitable for, and assist, plant production by contributing to the plants nutrient requirements.
The advantages produced by integrating aquaculture with conventional terrestrial and aquatic plant production systems have been summarised by Gooley and Gavine (2003) as:
An increase in farm productivity and profitability without any net increase in water consumption (Chap. 2).
Farm diversification into higher-value crops, including high-value aquaticspecies.
Reuse of otherwise wasted on-farm resources (e.g. capture and reuse of nutrientsand water).
Reduction of net environmental impacts of semi-intensive and intensive farmingpractices.
Net economic benefits by offsetting existing farm capital and operating expenses (Chap. 18).
Aquaponics has been said to have evolved from relatively ancient agriculture practices associated with integrating fish culture with plant production, especially those developed within the South East Asian, flooded rice paddy farming context and South American Chinampa, floating island, agriculture practices (Komives and Junge 2015). In reality, historically, fish were rarely actively added to rice paddy fields until the nineteenth century (Halwart and Gupta 2004) and were present in very low densities which would not contribute to any substantial nutritive assistance to the plants. Chinampas were traditionally built on lakes in Mexico where nutrient
advantages may have been supplied via the eutrophic or semi-eutrophic lake sediments rather than directly from any designed or actively integrated fish production system (Morehart 2016; Baquedano 1993).
Modern aquaponics started in the USA in the 1970s and was co-evolved by several institutions with an interest in more sustainable farming practices. Early important work was performed by several researchers, but ultimately, the progenitor of nearly all modern aquaponics is thought to be the work performed by, and the systems produced by, James Rakocy and his team at the University of the Virgin Islands (UVI) starting in the early 1980s (Lennard 2017).
Aquaponics is now considered a new and emerging industry with a relevant place in the broader, global agricultural production context and there are a number of variations of the technology of integrating fish culture with aquatic plant culture that are collectively defined under the aquaponics banner or name (Knaus and Palm 2017). Therefore, aquaponics seeks to integrate aquaculture animal production with hydroponic plant production using various methods to share water and nutrient resources between the major production components to produce commercial and saleable fish and plant products.