Aquaponics
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Aquaponics (IPA: /ˈækwəˈpɒnɪks/) is the symbiotic cultivation of plants and aquatic animals in a recirculating environment.
Aquatic animal effluent (for example fish waste) accumulates in water as a by-product of keeping them in a closed system or tank (for example a recirculating aquaculture system). The effluent-rich water becomes high in plant nutrients but this is correspondingly toxic to the aquatic animal.
Plants are grown in a way (for example a hydroponic system) that enables them to utilize the nutrient-rich water. The plants uptake the nutrients, reducing or eliminating the water's toxicity for the aquatic animal.
The water, now clean, is returned to the aquatic animal environment and the cycle continues. Aquaponic systems do not discharge or exchange water. The systems rely on the natural relationship between the aquatic animals and the plants to maintain the environment. Water is only added to replace water loss from absorption by the plants or evaporation into the air.
Aquaponic systems vary in size from small indoor units to large commercial units. They can use fresh or salt water depending on the aquatic animal (fresh or salt water).
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[edit] History
[edit] Before
"Integrated vegetable growing and fish farming polyculture systems have long been used in Far Eastern countries such as China and Thailand. Farm wastes are commonly added as feed to fish ponds and fish are often cultured in flooded rice paddies." [1]
At the New Alchemy Institute (1971 - 1991) researchers experimented with bioshelters and wastewater management via crop production. This pursuit, of what was to become the permaculture movement, inspired like-minded researchers to advance the concept of fish effluent as fertilizer for crop production.
In 1974 "The Journal of New Alchemists No.2" was published by the New Alchemy Institute and contained an article by William McLarney "Irrigation of Garden Vegetables with Fertile Fish Pond Water". This article was followed with "Further Experiments in the Irrigation of Garden Vegetables with Fertile Fish Pond Water" by William McLarney in 1976 in "The Journal of the New Alchemists No.3". Still neither of these were symbiotic relationships in a recirculating environment.
[edit] Beginnings
Formal interest in the combining of aquaculture and hydroponics seems to have started in the mid-1970s. In 1975 K. Sneed, K. Allen and JE Ellis wrote one of the first articles about integrating fish farming and hydroponics.[2] It would take another decade however before a greater amount of research in the integration of the two areas would start to crystallize into the true begins of aquaponics.
In the late 1970s Ronald D. Zweig and several other researchers published articles with the New Alchemy Institute about Fish Culture Systems and Solar-Algae Ponds. The progression of this study saw the integration of plants into the system. Ronald Zweig published "An Integrated Fish Culture Hydroponic Vegetable Production System" in the Aquaculture Magazine May/June 1986 pp34-40. It has been called "the most advanced form of aquaculture developed at New Alchemy - the Zweig hydroponic aquaculture pond - which grows both edible fish and floating hydroponic lettuce".[3]
In 1985, North Carolina State University (then) graduate student, Mark R. McMurtry, and professors Douglas C. Sanders, Paul V. Nelson, et al. created the first known recirculating (closed-loop), reciprocating (flood and drain) "aquaponic" system (called an Integrated Aqua-Vegeculture System) that filtered Tilapia effluent into sand biofilters (bacteria and alga) planted with Tomato and/or other vegetable crops.[3] From the mid-1980s and throughout the 1990s both McMurtry and Sanders published a number of articles on their research and worked to develop the recirculatory techniques for the arid Third World, particularly in sub-Saharan Africa.
[edit] Modern
Many institutions and enterprises followed on the efforts (replicated peer-reviewed research, active publication, dissemination and technology transfer) at North Carolina State University [4]; notably by the University of Arizona Environmental Research Labs, NASA/CELSS, S&S Aquafarms, The Freshwater Institute, University of Arkansas (?), Bioshelters, Inc (?), Global Aquatics, Inslee Fish Farms (?) and others who carried out (mostly proprietary and unpublished) 'research and development' of aquaponics.
From the 1980s to present day the two distinct aquaponic systems are;
- 1) "Deep Water" or "Raft Culture" aquaponics which is the primarily research carried out at the University of the Virgin Islands under the guidance of Dr. James Rakocy [5] and;
- 2) Reciprocating aquaponics ("Ebb and Flow" or "Flood and Drain") based on the techniques developed by Mark McMurtry, et al. at NCSU (such as that implemented by Tom and Paula Speraneo of S&S Aquafarms in West Plains, Missouri.[6])
[edit] Advantages
The unique advantages of aquaponic systems are:
- Conservation through constant water reuse and recycling.
- Organic fertilization of plants with natural fish emulsion.
- The elimination of solid waste disposal from intensive aquaculture.
- The reduction of needed cropland to produce like crops.
- The overall reduction of environmental footprint for crop production.
- Small efficient commercial installations can be built close to markets therefore reducing food miles.
[edit] Disadvantages
Distinct disadvantages inherent with aquaponics are:
- Initial expense for housing, tank, plumbing, pump/s, and grow beds.
- The infinite number of ways in which a system can be configured lends itself to equally varying results, conflicting research, and successes or failures.
- Some Aquaponic installations rely heavily on man-made energy, technology solutions, and environmental control to achieve recirculation and water/ambient temperatures but a system designed with energy conservation in mind (such as utilizing solar heating and the exploitation of gravity to reduce pumping) can be extremely energy efficient.
- Whilst careful design can minimize the risk, Aquaponics systems can have multiple 'single points of failure' where problems such as an electrical failure or pipe blockage can lead to a complete loss of fish stock.
- Like all aquaculture based systems, stock feed usually consists of fish meal derived from lower value species. Ongoing depletion of wild fish stocks makes this practice unsustainable.
[edit] More uses
Aquaponic systems can be used to replicate controlled wetland conditions that are useful for reclaiming potable water from typical household sewage, in addition to generating a continual supply of food with minimal fertilizer use. Aquaponics takes advantage of synergy between self-organizing biological systems, emphasizing the one element/many functions principle of permaculture as a natural solution for water treatment.
[edit] Fish
In practice, tilapia are the most popular fish chosen for home and commercial projects that are intended to raise edible fish. Most green leafy vegetables grow well in the hydroponic filter. Although sometimes selected minerals or nutrients such as iron are added, the main source of nutrients for the plants is the fish waste. In Australia, due to a ban on Tilapia in all states bar W.A., natives are the most popular fish, including Silver Perch, Murray cod and barramundi.
[edit] Gallery
 Silver Perch fingerlings in an aquaponic system. |
 Flood and Drain aquaponic system. |
 Plant bed in an aquaponic system. |
 Silver Perch in an aquaponic system. |
[edit] See also
[edit] References
[edit] Further reading
- Recirculating Aquaculture Tank Production Systems: Aquaponics—Integrating Fish and Plant Culture - James E. Rakocy, Michael P. Masser and Thomas M. Losordo - Southern Regional Aquaculture Center Publication #454 - http://www.aces.edu/dept/fisheries/aquaculture/documents/309884-SRAC454.pdf
- Aquaponics—Integration of Hydroponics with Aquaculture - By Steve Diver NCAT Agriculture
Specialist © 2006 NCAT - http://attra.ncat.org/attra-pub/PDF/aquaponic.pdf
