Copper and Mercury Altered Oxidative Metabolism in Selected Freshwater Aquatic Organisms

The major function of carbohydrates in metabolism is as a fuel to be oxidized and provide energy for their metabolic process. It is noteworthy that heavy metals like copper and mercury tend to create drastic disturbances in the oxidative metabolism of aquatic organisms, which can lead to death. In this connection, an attempt has been made to study toxic profiles of sublethal concentrations of copper and mercury in selected edible aquatic organisms with particular reference to carbohydrate and oxidative metabolisms. The decreased levels of tissue total carbohydrate glycogen, citric acid cycle enzymes and increased levels of cytosolic enzyme activities indicate the hypoxic condition induced by copper and mercury. Increased time of exposure from 7 to15 days, total carbohydrates and glycogen contents, activity levels of mitochondrial succinate dehydrogenase (SDH) in hepatic and muscle tissue (Hepatic fish, 0.267; snail, 0.245; crab, 0.185; muscle: fish, 0.145; snail, 0.180; crab, 0.114) were drastically decreased. In contrast, lactate dehydrogenase (LDH) and glutamate dehydrogenase (GDH) activity levels were increased significantly. All the animal hepatic tissue with reference to carbohydrate and oxidative metabolism showed maximum depletion when compared to muscle tissue. Hence, it is concluded that the heavy metals like copper and mercury create un-recoverable changes in carbohydrate and oxidative metabolism in aquatic organisms which leads to the death of organism.