Changes in the physical condition of Meretrix casta exposed to water-soluble fractions of refined and crude oil

Abstract

Meretrix casta were exposed to water-soluble fractions (WSF) of diesel, engine oil (Servo 30), and Kuwait crude, for a period of 30 days and changes in their wet weight, percentage dry weight and condition index were observed. No significant alteration in shell growth was noted during the experimental period but clams treated with 1.22 mg/L (0.5 Sublethal Toxic Unit) and 2.34 mg/L (1.0 S.T.U.) WSF of diesel; 1.93 mg/L (1.0 S.T.U.) WSF of engine oil and 3.18 mg/L (1.0 S.T.U.) WSF of crude, were noted to lose dry weight faster than wet weight when compared to control animals. Changes in the condition index of both controls and experimental forms were directly proportional to dry weight. Mortalities of 30% and 5% were noticed among diesel and engine oil-treated animals, respectively, indicating a definite stress experienced by these animals when compared to crude treated forms.