White Leg Prawn

Litopenaeus vannamei

Nutrient Pollution

Vannamei farmers continually seek to improve the efficiency of feeding methods in order to reduce operational costs and to minimise wasted feed settling on the bottom of the pond1, 2. Waste feed, along with other organic discharges from farming operations, can potentially lead to pollution of receiving waters and adversely affect aquatic life through de-oxygenation and algal blooms which can be associated with nutrient increase. Organic matter can also be deposited and accumulate around discharge points. The key nutrients likely to cause problems for receiving water bodies are nitrogen and phosphorus3.

The type and quality of feed used will affect the discharge of nutrients. To improve their performance farms should monitor feed utilisation efficiency, the quality of the pond effluents and water quality in the receiving water body. Monitoring methods are documented within certification standards.

Farms should also document and record how they dispose of pond sludge and any other solid wastes. The use of sedimentation basins or dedicated ponds to capture particulates is effective but more work is required to remove dissolved nutrients4. One area of growing interest is the use of clean-up technologies such as constructed wetlands which allow plants to remove dissolved nutrients1, 5, 6, 7. These plants can then be harvested giving the farmer an alternative income stream.

References

  1. Anh, P.T. et al, 2010. Water pollution by intensive brackish shrimp farming in south-east Vietnam: Causes and options for control, Agricultural Water Management, Vol97, Iss 6, 2010 p872-882
  2. FAO
  3. Herath, S.S. and Satoh, S., 2015. Environmental impact of phosphorus and nitrogen from aquaculture. InTechnology and Nutrition, edited by Allen Davis, D., 2015, p369-386, Feed and Feeding Practices in Aquaculture
  4. Jackson, C.J. et al, 2003. Managing the development of sustainable shrimp farming in Australia: the role of sedimentation ponds in treatment of farm discharge water, Aquaculture, Vol 226, Iss1–4, 31, 2003 p23-34
  5. Santos, A.A.O. et al, 2015. Comparing environmental impacts of native and introduced freshwater prawn farming in Brazil and the influence of better effluent management using LCA, Aquaculture, Volume 444, 2015 p151-159
  6. Jegatheesan, V. et al, 2007. Technological advances in aquaculture farms for minimal effluent discharge to oceans, Journal of Cleaner Production, Vol 15, Iss16, 2007 p1535-1544
  7. Castine, S. A. et al, 2013, Wastewater treatment for land-based aquaculture: improvements and value-adding alternatives in model systems from Australia. Aquaculture Environment Interactions, Vol. 4, 2013 p285-300