TOXICITY OF PETROLEUM HYDROCARBONS ON VILLORITA CYPRINOIDES var. COCHINENSIS AND PERNA INDICA

Petroleum hydrocarbons (PHC’s) are a serious pollutant of the aquatic environment. In the present context of increasing transport of petroleum products through the oceans the marine environment is always poised for pollution by PHC’s. These pollutants sink to the bottom and get incorporated into the bottom sediments. The bivalve mollusks rapidly accumulate a wide spectrum of PHC’s into their tissues. Experiments were conducted to evaluate the lethal and sublethal toxicity of the Water Accommodated Fractions (WAF) of two petroleum products, Light Diesel Oil (LDO) and Persian Gulf Crude (PG Crude) on two selected bivalves. The animals selected were the black clam Villorita cyprinoides var. cochinensis (Hanley) a hardy bivalve clam and the brown mussel Perna indica (Kuriakose and Nair, 1976). Of the two oils tested LDO was found to exert more pronounced effect on both the animals with 96 h LC 50 values of 17.28ppm and 4.62ppm respectively for the clam and mussel. Rate of oxygen consumption in the clam was found to increase on short term exposure to LDO (WAF) while the rate has reduced to 50% in the mussel at a concentration of 1.2ppm.