Sublethal effects of manganese on the carbohydrate metabolism of Oreochromis mossambicus after acute and chronic exposure

Carbohydrate metabolism variables of Oreochromis mossambicus were investiga ted after acute and chronic sublethal manganese exposure. The sublethal con centrations were determined from the LC50 value of manganese. After the exp osures, the fish were carefully netted and blood was drawn from the caudal aorta. The differences in the values of carbohydrate metabolism variables o f exposed fish were measured against control values and statistically analy sed to prove statistically significant differences in variable values, caus ed by the metal pollutant (P < 0.05). The results obtained showed changes i n the carbohydrate metabolism variables (glucose, lactate, glucose-6-phosph ate dehydrogenase and pyruvate kinase concentrations). These alterations ar e produced as a result of increased levels of cortisol and catecholamines, as well as hypoxic conditions. The latter induce hyperglycemia and increase d lactate levels. Hypoxia may be a result of the damaging effect of mangane se on the gills after exposure. The enzymes involved in the carbohydrate me tabolism are sensitive to metal exposure and therefore enzyme concentration s fluctuated after the exposure to manganese. Enzyme Function plays an impo rtant role in the catalysing of chemical reactions in an organism and the d isturbance thereof could lead to death. Fish enzyme levels are therefore im portant biomarkers in the event of metal pollution in a water source.