Effect of Physico-chemical variables on growth and condition index of rock oyster, Saccostrea cucullata (Born) in the Sunderbans.

Abstract

The effect of physico-chemical variables on the growth of the edible oyster, Saccostrea cucullata in the Sundarbans, India was investigated in a culture experiment. The results of the study indicate that the oysters grow better in high saline and pH conditions. High phytoplankton density is needed as feed for the oysters. The region of rich mangrove vegetation contributes substantial nutrients in the aquatic subsystem through litter and detritus and thereby enhancing the phytoplankton density and diversity. The aquatic subsystem of Ganges estuary is highly turbid due to the influx of river discharge and runoff into the system. Such a condition is not favourable for the growth and survival of the oysters. The condition index of oysters showed a unique seasonal variation with highest value during pre-monsoon and lowest during monsoon. There is an effect on the spawning process in which the gametes are released during the period of high salinity, pH and water temperature. This study demonstrated that the culture of S. cucullata can be accepted as an alternative sustainable livelihood in the Sundarbans as no external addition of chemical nutrients to enhance the growth of the oysters is required.