Assessment of nitrogen and sulphur cycle bacteria and shrimp production in ponds treated with biological products

Objective: To study the influence of biological products on the levels of nitrogen and sulphur cycle bacteria in shrimp culture systems of West Bengal, India. Methods: The pond water and sediment samples were analyzed for physico-chemical parameters as per standard methods. The bacteria involved in ammonification, nitrification, denitrification, sulphate reduction and sulphur oxidation were enumerated by most probable number technique. Results: The semi-intensive and modified extensive shrimp farms used a variety of biological products during various stages of production. No biological products were used in traditional farms. The water and sediment samples of modified extensive system recorded significantly higher mean heterotrophic bacterial counts. The counts of ammonia, nitrite and sulphur oxidizers, and nitrate and sulphate reducers varied among the systems. The cycling of nitrogen and sulphur appeared to be affected with the intensification of culture practices. Conclusions: The application of biological products in certain systems helped to maintain the bacteria involved in nitrogen and sulphur cycles and safe levels of ammonia, nitrite and nitrate. An assessment of these metabolically active bacteria in shrimp culture ponds and the application of right kind microbial products would help ameliorate the organic pollution in shrimp aquaculture