Influence of Environmental Factors on Growth Rate of Crassostrea madrasensis (Preston) in Suspended Culture

Growth response of Crassostrea madrasensis to varying environmental factors in the Mulki estuary of Karnataka was investigated from April 2004 to March 2005. Temperature, salinity, pH, particulate organic matter (POM), particulate inorganic matter (PIM), total particulate matter (TPM) and chlorophyll a (Chl a) levels were correlated with growth in shell length. Marked seasonal patterns in growth rate were observed in relation to changes in environmental factors. Growth curve indicated a rapid phase (16.21±1.2 mm month-1) initially (May-June) followed by a slow phase (0.8±0.52 mm month-1) coinciding with the drop in salinity (August-September). Considering the temporal variations of environmental factors, their influence on growth rate was analysed seasonally. The growth rate was significantly correlated with Chl a concentrations in all the seasons. A pronounced seasonal cycle was noticed in Chl a levels resulting from blooms in pre-monsoon (April-May) and post-monsoon (October) seasons