ACUTE NEUROTOXICITY OF CHLORPYRIFOS AND CYPERMETHRIN MIXTURES ON JUVENILE Clarias gariepinus (BURCHELL, 1822): ACETYLCHOLINESTERASE (ACHE) AND BEHAVIOURALCHARACTERISTICS

ABSTRACT

This study was conducted to investigate the effects of acute neurotoxicity of complex mixtures of chlorpyrifos (an organophosphate) and cypermethrin (a pyrethroid) on juvenile clariasgariepinus using acetylcholinesterase (ache) and behaviour as endpoints. The experimental fishes were exposed to15µg/l,30µg/l and 45µg/l of chlorpyrifos and20µg/l, 40µg/l and 60µg/l of cypermethrin individually and as a mixture for 96hours in triplicates. The levels of acetylcholinesterase in the Cypermethrin exposed groups were found to significantly decrease in a concentration-dependent pattern. Conversely, an increase in AChE levelsobserved in chlorpyrifos group and the mixture toxicity groups. The exposure of juvenile C.gariepinus to chlorpyrifosand cypermethrin individually and as a mixture resulted in erratic swimming, air gulping, lethargy and discolouration. Thesebehavioural changes were dose-dependent. The result from this study confirms that exposure to chlorpyrifos and cypermethrin individually and as a mixture even at environmentally relevant concentrations could lead to disruption in the normal neurological wellbeing of aquatic organisms such as C.gariepinus, thereby endangeringfish population in the wild.