Impact of industrial effluent on water quality and gill pathology of clarias gariepinus from Alaro Stream, Ibadan, Southwest, Nigeria
Hydrobiology and Fisheries Unit, Department of Zoology, University of Ibadan, Nigeria
Adeogun, A.O., Hydrobiology and Fisheries Unit, Department of Zoology, University of Ibadan, Nigeria
The responses of a freshwater fish to variations in water quality were evaluated using gill histopathology and condition factor of Clarias gariepinus from Alaro stream. Alaro stream receives industrial effluent as a point source and water quality parameters (pH, dissolved oxygen (DO), temperature, Electrical conductivity (EC), Alkalinity, Biochemical Oxygen demand (BOD) and Total dissolved solids (TDS)) and metals (Copper (Cu), Zinc (Zn), Cadmium (Cd) and Iron (Fe)) were analysed from nine sampling sites (upstream, effluent discharge point and downstream) using standard methods. The average values of all physico-chemical parameters (except pH and DO) and metals were considerably higher downstream than upstream while effluent discharge point showed the highest values for all sampling sites. The lowest values for pH and DO were also recorded at effluent discharge point and concentrations of Fe downstream exceeded acceptable limits for surface waters. Gill histopathological lesions observed in fish downstream included severe necrosis, oedema, erosion of gill villi, matting of gill filaments with focal areas of haemorrhage. Significant (p<0.05) decreases in body weight and condition factor (CF) were recorded for fish downstream of effluent discharge point compared to fish upstream. Fish displayed impaired health (poor CF) attributed to changes in water quality due to industrial wastewater discharge. This resulted in irreversible compensatory responses of the gill tissue as evidenced in altered histopathology of the gills. © EuroJournals Publishing, Inc. 2012.