Posted January 11th 2011 at 1:53 pm by
in Aquaponics Project in Lynn

What is aquaponics anyway?

The Lynn Aquaponics series is about an effort in Lynn, Massachusetts to stimulate a green and socially equitable economy in Lynn, Massachusetts. One of their cornerstone projects is an aquaponics facility.

Aquaponics has attracted much attention as a novel type of sustainable agriculture [2].

But what is aquaponics?

Aquaponics is agriculture that combines hydroponics, the method of growing plants in nutrified water instead of soil, and aquaculture, the cultivation of fish for food [1]. Aquaponics not only produces plant and animal crops but also uses these fish and plants to recycle nutrients and waste in a sustainable, recirculating and ever-connected system. Its internal recycling system between animals and plants incorporates the nutrient recycling system that is found in natural environments.

aquaponics diagramA simple diagram of the nutrient cycle in an aquaponics system

The most important nutrient in this recycling system is nitrogen. Fish release two types of waste: dissolved nitrogen waste and solid waste. Bacteria in the water eventually convert the dissolved nitrogen waste into another type of waste called nitrate [2]. Nitrate is toxic to fish. In aquaculture systems that only raise fish, growers have to manually filter out the nitrate and throw it away as waste.

Aquaponics, on the other hand, grows plant crops that absorb nitrate through their roots. This nitrate absorption helps plant growth in addition to protecting the fish from poisonous dissolved waste.

In nature, fish’s solid waste is broken down not by bacteria but by earthworms. Some aquaponics systems include earthworms as one of their components in order to be better process solid waste. Such systems remove solid waste from the fish tank and put it into a compost system where the worms break down the solids into vermicompost, another nutrient-rich food source for plants [2].

One of the few outside inputs that aquaponics may need is fish feed. But even fish feed can come from the aquaponics system itself if growers grow duckweed, a water plant that many fish species eat.

Though many different species of fish can thrive in an aquaponics system, tilapia is one of the best suited for aquaponics [1]. Tilapia eat duckweed and adapt to a wide variety of water conditions. On the plant side, leafy vegetables like lettuce and herbs like basil thrive best in aquaponics [1].

Aquaponics systems can have a wide variety of appearances. Some, like the image below, feature pre-fabricated industrial-size tanks outfitted with complicated filtration technology while others, like the demonstration system in Lynn, are simpler, homemade setups of plastic barrels and piping.

industrial aquaponicsAn example of industrial-scale commercial aquaponics [3]

LCGD aquaponicsMembers of the LCGD assemble their homemade aquaponics system. Photo courtesy of Elisha Goodman.

Despite any differences in appearance, all successful aquaponics systems faithfully adapt the nutrient recycling process already found in nature.  The success of their harvests depends on daily maintenance of the chemical and biological balance between the plants and animals in the system.

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[1] Diver, S. (2006). Aquaponics: Integration of Hydroponics with Aquaculture. ATTRA – National Sustainable Agriculture Information Service. Click here for article.

[2] Rakocy, J.E., Masser, M. P. & Losordo, T.M. (November 2006). Recirculating Aquaculture Tank Production Systems: Aquaponics—Integrating Fish and Plant Culture. Southern Regional Aquaculture Centure Publication No. 454. Click here for article.

[3] “Aquaponics: The Answer to Sustainable Farming.” Social Earth. 3 June 2009. Click here for article and image.

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