Water quality, nutrient dynamics and sediment profile in shrimp farms of the Sundarbans mangrove forest, Bangladesh

Abstract

Investigation was carried out to observe the sediment-water characteristics and nutrient budget of traditional shrimp farms during January- December 2000. Most of the water quality parameters between inlet and outlet of shrimp farms were similar, but transparency, turbidity, total suspended solid (TSS), phytoplankton and zooplankton concentration and primary productivity were significantly (p < 0.05) different within inlet and outlet. Pollution indicator parameter, chemical oxygen demand (COD) was more or less similar between these two points indicating less or no chance of coastal eutrophication from shrimp farm effluent. Nutrient balance due to water exchange showed that about 44.15 kg of nitrogen (N)/ha/culture cycle and 27.25 kg of phosphorus (P)/ha/culture cycle were being deposited into the bottom sediment. Most of the sediment parameters between mangrove and shrimp farms were similar, except calcium (Ca), magnesium (Mg), potassium (K) and sulphur (S). Nitrogen (N), Phosphorus (P), Organic matter (OM) contents were low in the sediment sample indicating the sediment status poor and needs improvement through proper fertilization.