Aquaculture is the breeding of marine animals in water. It can take place in natural water bodies such as ponds, lakes, marshland or brackish water and the ocean. It can also be conducted in man-made tanks, commonly found in fish hatcheries. Regardless of where it takes place, Aquaculture has an impact on the environment locally and globally. To become an environmentally sustainable activity and economically sound, is necessary to implement strict regulations on the management of resources and a careful site selection. Nevertheless, there is a natural alternative: Aquaponics.
Aquaponics is the breeding of marine animals in tanks or ponds using the fish tank water to grow without soil, vegetables, fruits or seaweed. It is a balanced closed system that recreates the same process we see in a natural pond where plants and animals thrive in perfect harmony.
The Aquaculture faces some environmental challenges that Aquaponics has naturally solved. I list these challenges below:
1. Effluents and waste management.
The practice of Aquaculture necessarily includes waste management. The effluents in these farms include uneaten food, metabolic excretions and feces. They consist of both organic solid waste and dissolved organic and inorganic nutrients, which are discharged in a daily basis into the environment. The flux of these compounds should never surpass the natural assimilation capacity of the local ecosystem because severe impacts, such as eutrophication, oxygen depletion and alteration of local biodiversity, can occur both in the water column and in the bottom substrate. To replace the discharged water is imperative refilled the tank with clean water. This involves extensive use of water resource.
In Aquaponics, there is no waste. It is a closed balanced ecosystem. What is considered waste in Aquaculture is useful input for the balance between the needs of the fish and the need of the vegetables. Bacterial colonies are responsible for the conversion of ammonia and nitrite to nitrogen readily assimilated by plants. Other potential participants are worms. They can decompose solid waste from the fish, excess roots and other materials that plants slough off, making them more bio-available for the plants. As a result of these multiple natural filters, there is clean water in fish tank all the time. There is no need to change and discharge the water to the natural environment. Less work for the farmer and no risk for the environment.
2. Origin and quality of food for the fish.
In Aquaculture, generally the food for the cultivated fish comes from fish in the ocean. This contributes to overharvest of the oceans. Another problem is that they are often pumped with hormones to promote rapid growth, and in some cases are even given chemicals to change their color, such synthetic astaxanthin to salmon to enhance the pink.
In order to preserve the health of the system and produce organic vegetables and fish, in Aquaponics the quality of the food is a priority. Hormones and other synthetic chemicals are not permitted in this closed system: they directly affect the metabolism of the plants. The diet of the fish can be naturally supplemented by the introduction of a worm farm, a black fly farm or duckweed tanks to complement high quality commercial food that often comes from vegetal protein sources, (as has been proposed by the National Organic Standards Board, limiting the amount of fishmeal and fish oils in organically certified aquaculture products).
3. Veterinary medicines.
In Aquaculture, like any factory-farmed meat, the living conditions of the animals are not optimal and are often kept alive by the continuous use of antibiotics. In addition, any medical treatment given to the cultivated fish poses a risk for the natural environment if the discharged water has not gone through adequate neutralization or dilution.
Antibiotics for fish are not permitted in Aquaponics because they can also affect the bacteria needed for the balance. The high oxygen levels in Aquaponics systems and the worms activity, help mitigate disease outbreaks in both fish and plants. In case there is a need to treat a particular disease, there is no risk of contaminating the natural environment.
4. Transfer of pathogens to wild stock populations
Aquaculture: with the need to drain the water, there is a risk of pathogen transfer to wild stock populations.
Since Aquaponics is a closed system, any problem regarding the health of the fish will be treated within the system. There is no risk of contaminating other species in the wild. This follows automatically from local regulations in which cultivated species should not be released to the environment. Aquaponics is a balanced ecosystem that promotes health and vitality both in fish and plants.
5. Antifouling products
Antifouling products are necessary to prevent or minimize biofouling in Aquaculture tanks. Biofouling is the gradual accumulation of organisms, like bacteria and protozoa, on the surfaces of the tanks in contact with water.
Since, biofouling is a natural process in a wet environment, in Aquaponics is not necessary to get rid of microorganisms or algae. As an ecosystem, they are part of the living equilibrium. For instance, algae is good food for some species of fish.
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Aquaponics, as we have seen, is a great option for those committed to sustainability, aiming to secure the future of our planet. It is a technique that can be used indefinitely as an endless virtuous cycle that will enable organic harvest all year. In addition, it is an excellent choice for those looking for efficiency and ease of operation in the route for food self-sufficiency.