Coupled Aquaponics Systems
Coupled aquaponics is the archetype form of aquaponics. The technical complexity increases with the scale of production and required water treatment, e.g. filtration, UV light for microbial control, automatic controlled feeding, computerization and biosecurity. Upscaling is realized through multiunit systems that allow staggered fish production, parallel cultivation of different plants and application of several hydroponic subsystems. The main task of coupled aquaponics is the purification of aquaculture process water through integration of plants which add economic benefits when selecting suitable species like herbs, medicinal plants or ornamentals. Thus, coupled aquaponics with closed water recirculation systems has a particular role to fulfil.
Under fully closed recirculation of nutrient enriched water, the symbiotic community of fish, plants and bacteria can result in higher yields compared with stand-alone fish production and/or plant cultivation. Fish and plant choices are highly diverse and only limited by water quality parameters, strongly influenced by fish feed, the plant cultivation area and component ratios that are often not ideal. Carps, tilapia and catfish are most commonly used, though more sensitive fish species and crayfish have been applied. Polyponics and additional fertilizers are methods to improve plant quality in the case of growth deficiencies, boosting plant production and increasing total yield.
The main advantages of coupled aquaponics are in the most efficient use of resources such as feed for nutrient input, phosphorous, water and energy as well as in an increase of fish welfare. The multivariate system design approach allows coupled aquaponics to be installed in all geographic regions, from the high latitudes to arid and desert regions, with specific adaptation to the local environmental conditions. This chapter provides an overview of the historical development, general system design, upscaling, saline and brackish water systems, fish and plant choices as well as management issues of coupled aquaponics especially in Europe.