Sublethal effects of copper and mercury on some biochemical constituents of the estuarine clam Villorita cyprinoides var. cochinensis (Hanley)

In estuarine clams exposed to copper(II) or mercury(II) (600 ug per litre), carotenoid content increased 4-fold and metabolic rate (oxygen uptake) decreased by 28-32 per cent within 48 h, though recovery was evident during 48-96 h exposure. After 24 h exposure, tissue lactic acid content had increased to 136 ug per g in copper exposed clams and to 124 ug per g in mercury exposed clams (control value 20 ug per g). After 72 h, tissue glycogen had decreased to 910 and 1188 ug per g in clams exposed to copper and mercury, respectively, compared with 1954 ug per g in controls. Similar, but less marked, biochemical changes were observed in clams exposed to 300 ug copper or mercury per litre for 96 h.