ABSTRACT

The effects of six (6) common-place and daily- produced environmental pollutants on fingerlings of Oreochromis niloticus and Clarias gariepinnus fish species were studied in the laboratory using continuous flow-through system. These pollutants were Ghyphospate, Hair dressing salon effluent, cassava mill effluent, used (waste) engine oil, Detergent KLIN® and Poultry droppings. Water quality parameters monitored during the study were pH, dissolved oxygen, free carbon dioxide, total alkalinity and temperature. Toxicological study was carried out to evaluate lethal and/ or sub-lethal effects on the two test fishes on exposure to concentrations of 20ppm, 40ppm, 60ppm, 80ppm and lOOppm ofthe different pollutants. All six (6) pollutants studied were found toxic to the test fishes. The fishes on exposure to the different pollutants generally showed unusually heightened movements, hyperactivated opercular plate and pectoral fin beat frequencies, loss of equilibrium, respiratory distress, epileptic buoyancy traits, periods ofquiescence and finally death. The 96hrLC50 determined for these toxicants for O. niloticus and C. gariepinnus were respectively-Glyphosphate 13.49pmm and 20.89ppm, Hair dressing salon effluent 18.62ppm and 19.05ppm, Detergent KLIN® 21.88ppm and 21.88ppm, used engine oil 19.05ppm and 18.20ppm, cassava mill effluent 18.20ppmm and 25.12ppm, Poultry droppings 27.54ppm and 30.20ppm. Oreochromis niloticus, a pelagic obligate herbivore was found to be more susceptible to the toxicants than was Clarias gariepinnus, a demersal obligate omnivore. The threshold (safe levels) of these toxicants with their corresponding lower and upper limits for Orechromis niloticus were respectivelyGlyphosphate 10.47ppm (10.94ppm lower and 16.63ppm Upper), Hair dressing salon effluent 14.13ppm (15.26ppm lower and 22.72ppm Upper), Detergent KLIN® 17.38ppm (17.79ppm lower and 26.91ppm Upper), Used engine oil 15.49ppm (16.45ppm lower and 22.06ppm Upper), Cassava mill effluent 12.88ppm (13.28ppm lower and 24.93ppm Upper), Poultry droppings 17.78ppm (23.08ppm lower and 32.86ppm Upper). For Clarias gariepinnus, the threshold (safe levels) of these toxicants with their corresponding lower and upper limits were respectively-Glyphosphate 13.18ppm (17.26ppm lower and 25.28ppm Upper), Hair dressing salon effluent 14.79ppm (15.36ppm lower and 23.62ppm Upper), Detergent KLIN® 15.49ppm (15.63ppm lower and 30.63ppm Upper), Used engine oil 13.18ppm (17.74 ppm lower and 35.57ppm Upper), Poultry droppings 19.05ppm (24.43ppm lower and 37.33ppm Upper). For Oreochrotnis niloticus, Used engine oil and Glyphosphate caused highest mortality (72%) of all toxicants, Detergent KLIN® and Hair Dressing salon effluent caused 65% mortality. For Clarias gariepinnus, Used engine oil and Glyphosphate again caused highest mortality (62%) of all six toxicants. Detergent KLIN ®, Hair dressing salon effluent, Cassava mill effluent and Poultry droppings caused lower death percentage at 60% mortality each.