In the clam bed the monthly average water temperature varied from 24.8 to 33.5°C, salinity 14.46 to 35.53 %o, dissolved oxygen 3.78 to 7.00 ml/1, pH 6.55 to 7.00, phosphate-P 1.98 to 7.08 /µg at/1, nitrate N 1.70-6.62 fig at/1, nitrite-N 0.66 to 2.94 /µg at/1 and silicate-Si 24.68 to 78.00 Mg at/1. The monthly average organic carbon of the sediment ranged from 0.55 to 1.26 %. The seasonal variations of these parameters are studied. The habitat preferences of the blood clam Anadara granosa are discussed in relation to some of the environmental factors.