THE EFFECT OF COPPER ON THE BLOOD-CHEMISTRY OF CLARIAS-GARIEPINUS (CLARIIDAE)

Environmental stressors, both natural and humanly induced, could cause changes in cellular function which alter the physiology of organ syst ems in fish. The need to comprehend and predict the condition which st ress metals will pose on fish, and extrapolate the effect of pollutant s from laboratory to population levels, have forced scientists to sear ch for physiological and biochemical indicators of health and subletha l toxicant effects. Hematological evaluation of fish blood provides va luable facts concerning the physiological response of fish to changes in the external environment. Furthermore, hematological Variables are well known for their clinical value in prognosis and diagnosis. Sublet hal responses after exposure to toxicants can be determined by commonl y applied techniques. Measurements for a number of hematological and c arbohydrate metabolic variables were recorded at winter and summer tem peratures after fish, acclimated for 3 months to experimental conditio ns, were exposed to sublethal concentrations of copper for 96 hr in a continuous-flow experimental system. Controls were run at the same tim e to establish essential baseline hematological values. Fish were expo sed to the mean copper concentration as was found in the Olifants Rive r, Kruger National Park, during summer(0.05 +/- 0.032 mg liter(-1)) an d winter (0.085 +/- 0.032 mg liter(-1)) to establish the effect thereo f on the variables mentioned. The results proved that the concentratio n of copper in the river exerts a physiological effect on Clarias gari epinus at 21 +/- 1 and 28 +/- 1 degrees C which manifests in changed b lood chemistry. Pathological conditions, such as erythrocytopenia, leu cocytosis, hyperglycemia, and hyperprotonemia, are evident. The fish p hysiologically adapted to the environmental change, which does not nec essarily reflect a State of normality. (C) 1994 Academic Press, Inc.