EFFECT OF CHROMIUM ON OXYGEN CONSUMPTION AND GILL HISTOLOGY OF THE ESTUARINE CLAM,MERETRIX CASTA

摘要

The cytotoxic effect of the heavy metal chromium on oxygen consumption and histology of the gills of Merlrix easia was studied. Merlrix casia were exposed for 10.20 and 30 days in 10% sub lethal concentration of 96 hr LC_(50) of chromium (4.25 mg/l). An acceleration (+45.85%) in respiratory rate was observed in the clam exposed to sublethal concentration (SLC) of 10% on 10th day of exposure. However, a decline (-35.65 & -68.40%) in the rate of respiration was recorded when they were exposed for a prolonged period of 20 and 30 days. The gills exposed to SLC of chromium showed mild morphological alterations during 10 days of exposure. However, after 30 days, fusion of adjacent lamellae, vacuolization, clumping of lamellae and hyperplasia were prominent. All these alterations finally caused the failure of respiratory mechanism, which resulted in the death of the test mussel.