The impact of shrimp pond effluent on water quality of Vasishta Godavari estuary with respect to brackishwater aquaculture, East Coast of India.

Abstract

Estuary, where a river meets the Sea, provides high level nutrients both in water column and in sediment, making estuaries most productive natural habitat for brackish water aquaculture in the world. Estuary is subject both to marine influences and to river influences, causes variations in optimum hydro chemical parameters, which are suitable for brackish water aquaculture. Physicochemical studies were carried out to predict whether the variations are due to seasonal changes or due to aquaculture effluents in Vasishta Godavari Estuary (VGE).Towards this objective water samples were collected in VGE from five stations during Oct-2016; Monsoon with Farm Period (FP)-1 discharge, Jan-2017; Postmonsoon with FP-2 beginning ,June-17;Premonsoon with FP-3 discharge. Influence of seawater was felt in the estuary up to a distance of 40 km from the mouth towards the head.Though fluctuations in physicochemical parameters were noticed, these are in optimum range for brackish water aquaculture. Concentration of nitrate, silicate was rich, where as phosphate, nitrite was poor. Salinity stratification was more marked than that of dissolved oxygen. Salinity gradient (surface to bottom) increases towards seaward during the discharges of FP-1 & FP-3 and not follows any trend during the beginning of FP-2. The field and laboratory observations on the water quality during the discharge and beginning of farm periods revealed that the study area have high potential for brackish water pond shrimp culture development based on values obtained which were in conformity with recommended values for shrimp culture.