Water and bottom sediments quality of brackish water shrimp farms in Kaliganj Upazila, Satkhira, Bangladesh

Shrimp culture plays a central part in the fisheries sector of Bangladesh that leads to a significant change in the structure and composition of frozen food export sector. An investigation was carried out to determine physiochemical parameters, nutrients content, bacterial contamination and metal content in shrimp “Gher” (Farms) water and sediments. Physicochemical parameters were analyzed in situ by portable meters. Ammonia, phosphate, bacterial counts, and metals contents were analyzed by Nesslerization, colorimetric and standard microbiological methods and Atomic Absorption Spectrophotometery (AAS), respectively. Except Dissolve oxygen and temperature all other physiochemical parameters were unsuitable for shrimp culture. The concentration of ammonia was 0.384 to 1.5 mg L^-1 and the concentration of phosphate ranged from 0.02 to 0.818 mg L^-1. In bacteriological analysis, highest levels of coliform were found in the tested samples and total colifom count reached up to 2.04x103 cfu mL^-1. Among the tested metals, Cr was highest in water and sediment samples. Concentration of Cr ranged from 0.150 to 0.807 mg L^-1 and 1.957 to 3.436 mg kg^-1 in water and sediment samples, respectively. A significant difference was observed for the concentration of metals in sediment and water samples. The high concentration of nutrients and metals in shrimp “Gher” water and sediment as well as the presence of pathogenic bacteria in the “Gher” and river water indicated unhygienic environment and the sources of contamination of shrimp “Gher”.