Physicochemical properties of sediments and water in shrimp farms of Dacope Upazilla in south-west coastal region of Bangladesh

Sediments and water quality parameters are the key determinants for sustainable shrimp farming in Bangladesh. In this context, an investigation was carried out to assess the physicochemical properties of sediments and water in shrimp farming areas of Dacope Upazilla of Bangladesh. The data were collected from 21 shrimp farms located in three villages of Dacope Upazilla of Khulna district and the farms were categorized in three different groups including freshwater shrimp + rice, brackish water shrimp + rice and brackish water shrimp farm. Water samples were analyzed for determining quality parameters such as pH, electrical conductivity (EC) and total dissolved solids (TDS). Chemical analyses of both sediments and water samples were done for P, K, S, Ca and Mg contents while total N determination was performed only for soil samples. The values of pH, EC and TDS of water samples in three different shrimp farms ranged from 6.12 to 8.99, 2.10 to 23.50 dS/m and 103 to 437 mg/L, respectively. The contents of P, K, S, Ca and Mg contents in water samples of three different shrimp farms ranged from 1.17 to 4.93 mg/L, 8.57 to 38.24 mg/L, 10.65 to 47.48 mg/L, 65.22 to 273.49 mg/L and 45.38 to 243.85 mg/L, respectively. On the other hand, the contents of total N, available P, exchangeable K, available S, Ca and Mg contents in sediment samples of three different shrimp farms ranged from 0.112 to 0.289%, 13.58 to 50.61 µg/g , o.51 to 2.28 me/100g , 111.26 to 150.91 µg/g , 3.46 to 20.64 me/100g and 2.20 to 14.58 me/100g, respectively. For both sediments and water samples, the highest values of quality parameters and nutrient contents were found in brackish water shrimp farm while the lowest values were recorded in freshwater shrimp + rice farm which might be due to level of salinity, farm practices (feed, antibiotics and other chemicals) and season of the year. Hence, the impact of shrimp farming could be minimized by flushing saline water to leach salinity of sediments in time with available supply of freshwater in association with rice cultivation.