Aerators, especially paddlewheels, are often used to mix the water and address oxygen stratification in ponds. However, most aerators do not provide the most efficient and power-conscious service. Due to thermal and oxygen stratification in ponds, the efficiency of paddlewheel aerators is low, and other present-day aerators have other problems. Emerging designs should better address effective mixing and aerating of pond water.
Dozens of land-based, closed-containment salmonid RAS systems are coming on line. New projects are bringing new principles into the salmon industry. Industry expansion hinges upon the development of pollution-mitigating technologies to reduce nutrients in effluents.
Aquaculture certification programs essentially mark milestones on the journey toward more sustainable practices. There is a role for a clearly defined starting point of “minimum acceptable standards,” but it is equally important to create incentive structures to enable producers to “move up the ladder” and differentiate themselves regarding what constitutes best practices and highest quality.
Aquaculture effluent can be an effective fertilizer in land-based plant production. Research with tilapia utilized dewatered aquaculture effluent (A.E.) as a partial substrate replacement for tomato plant seedlings. Seedling growth decreased when effluent replaced a commercial growing mix at 25 percent or more.
An important criterion when studying biofilters is the conversion rate of total ammonia nitrogen (TAN) to nitrate-nitrogen in production water. Although nitrification rates have been based on media surface areas, they do not always reflect the actual nitrification achieved. Volumetric TAN conversion rate is a direct measure based on filter volume.
Peracetic acid products, which have strong anti-microbial effects, can be used as sanitizers to control water quality in aquaculture systems.
In life cycle analysis of aquaculture, there is a danger of the entire array of embodied resources and impacts being assigned to the production facility. Producers have no control over the inefficiencies or impacts associated with feed production, but can help lessen resource use through good management practices.
Shrimp culture in coastal Bangladesh is threatened by climate change variables that include flooding, cyclones, drought, salinity changes and rising sea levels. Holistic planning can help reduce the impacts.
Under cultivation, macroalgae grow rapidly and synthesize large amounts of carbon/energy reserves while utilizing wastewater. Seaweed can remove pollutants from industrial agriculture effluent and reduce coastal eutrophication.
The creation and application of reference tables for acceptable concentration ranges of physical and chemical water quality variables for culture organisms would be challenging due to the differing tolerances found among the many farmed species.
The authors believe that dry-out periods likely destroy most organisms in pond bottoms, and liming of the entire bottom area should be done only to neutralize soil acidity and increase pH for organic matter decomposition by soil microorganisms.
The main pond bottom soil management practices used in semi-intensive culture are pond dry-out and liming between crops. These practices accelerate organic matter decomposition, neutralize soil acidity and destroy unwanted organisms.
To quantify the carbon dioxide and methane fluxes in tropical earthen ponds, the authors used freshwater prawn farming managed according to different strategies as a model.
The integration of marine and brackish water aquaculture with plants can help lead to alternative food production on coastlines, in arid lands and in urban/periurban areas. Some 50 salt-tolerant plants could be cultivated for grains or biodiesel applications.
Copper is used for control of the blue-green algae responsible for off-flavors in aquaculture animals, treating diseases and parasites, and avoiding cage net fouling. Although copper is an essential nutrient for plants and animals, an excess can negatively affect the environment and human health.
Geotextile bags used in combination with polymer flocculant aid chemicals can provide effective primary treatment of recirculating aquaculture system effluent. Much of the suspended solids that carry the majority of the organic load within the effluent can be captured by these systems.