EFFECT OF COPPER ON THE HEMATOLOGY AND OSMOREGULATION OF THE MOZAMBIQUE TILAPIA, OREOCHROMIS-MOSSAMBICUS (CICHLIDAE)

The haematology of Oreachromis mossambicus was investigated after short-term (96 hr) exposures to 0.16 mg/l and 0.40 mg/l, respectively, as well as long-term (4 wk) exposure of 0.40 mg/l copper, at two temperatures, After the exposure of two sublethal copper concentrations a physiological effect was exerted on O. mossambicus, at both temperatures, by causing changes in the blood biochemistry such as leucocytosis and erythrocytopenia. Morphological changes in the gills, as reflected by the decreases in the plasma sodium, potassium, calcium and chloride concentrations, although not lethal, had a significant effect on the respiration and osmoregulatory function of the gills. Those morphological changes can be regarded as primary changes, which will inevitably lead to secondary physiological changes as well as responses that could affect various organ systems. Changes can be seen as an initial response to copper (the toxicant) or as an adaptation reaction to retain a normal condition.