CHANGES IN OXYGEN-CONSUMPTION AND BIOCHEMICAL-COMPOSITION OF THE MARINE FOULING DREISSINID BIVALVE MYTILOPSIS-SALLEI (RECLUZ) EXPOSED TO MERCURY

The effect mercury (Hg) on tolerance, oxygen consumption, and body bio chemical composition of a marine dreissinid bivalve Mytilopsis sallei was investigated. The 96-hr LC(50) of Hg for M. sallei was found to be 0.2571 mg/liter and the safe concentration was 2.6 mu g/liter. Exposu re of M. sallei to Hg resulted in a significant decrease in oxygen con sumption with increasing concentration of the metal. The effect of exp osure time and concentration of Hg on body biochemical composition was also studied in M. sallei. In time-dependent experiments, carbohydrat es were utilized, whereas both proteins and carbohydrates were consume d in concentration-dependent exposure. A decrease in the ratios of gly cogen/protein and glycogen/lipid was observed in time-dependent experi ments. In concentration-dependent experiments, there was also a decrea se in glycogen/lipid ratio but the glycogen/protein ratio was almost c onstant at all exposure concentrations. The caloric concentration was also presented for both time and concentration-dependent exposure of H g. However, the results of the present investigation indicate that thi s bivalve exhibited a differential preference in their utilization of biochemical constituents during time- and concentration-dependent stre ss of Hg. The decrease in oxygen consumption together with the utiliza tion of glycogen and carbohydrates during Hg exposure suggests that th ese bivalves might shift to anaerobic metabolism in order to encounter the heavy metal stress in the environment. (C) 1996 Academic Press, I nc.