Effect of Water Variables On Lead Tolerance in Postlarvae of Penaeus Indicus (H. Milne Edwards)

Lead tolerance in Penaeus indicus post-larvae (PL) was studied in relation to the water variables: salinity, temperature and pH. the LC 50 for 96 hrs was 7.22 ppm at ambient conditions of salinity (20% o ), temperature (29°C) and pH (7.2). the post-larvae were found to be sensitive to salinity variations with a significant (P < 0.05) low LC 50 values at lower (2% o ) and higher (29% o ) ranges. Though a decrease in LC 50 value was observed both at higher (45°C) and lower (10°C) temperatures, it was significantly (P < 0.05) low only at higher temperature indicating more toxicity. the LC 50 values also showed a significant (P < 0.05) decrease in acidic (pH 2.8) and alkaline (pH 11.0) conditions. the data indicate that lead toxicity increases in the PL of P. indicus with variations in the water variables.