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

The haematology of Oreachromis mossambicus was investigated after shor t-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 temperat ures, After the exposure of two sublethal copper concentrations a phys iological 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 co ncentrations, although not lethal, had a significant effect on the res piration and osmoregulatory function of the gills. Those morphological changes can be regarded as primary changes, which will inevitably lea d to secondary physiological changes as well as responses that could a ffect various organ systems. Changes can be seen as an initial respons e to copper (the toxicant) or as an adaptation reaction to retain a no rmal condition.