Journal Of Tropical Biosciences
Volume No: 10|
Page No: 18
| FullText PDF
Title: SOME ASPECTS OF THE ACUTE TOXICITY OF TANNERY EFFLUENT TO JUVENILE CLARIAS GARIEPINUS (TEUGELS, 1982)
GBEM, T.T. 1, Z. BARAK1, F.A LAWAL2, J.K. BALOGUN1, P.A. ANNUNE3 AND J. AUTA1*
1DEPARTMENT OF BIOLOGICAL SCIENCES, AHMADU BELLO UNIVERSITY ZARIA
2NATIONAL RESEARCH INSTITUTE FOR CHEMICAL TECHNOLOGY, ZARIA
3DEPARTMENT OF FISHERIES AND AQUACULTURE,&NBSP;UNIVERSITY OF AGRICULTURE, MAKURDI, NIGERIA
Juvenile Clarias gariepinus (Teugels) of mean weight 5.40 ± 0.4g and mean standard length 8.60 ± 1.0cm were exposed to composite tannery effluents following standardized toxicity testing methods. Effluent concentrations of 0%, 5%, 8%, 10%, 12% and 15% v/v were used. Symptoms of toxicity observed include increased gill ventilation, air gulping and spiral swimming with loss of balance. Mucus and peeled skin were observedon the bodies of dead and moribund fish. In addition, swollen abdomens were observed in fish exposed to higher concentrations. The 96hr LC50 of composite tannery effluent was 9.5% with 8.42-10.68% v/v confidence limit. Opercula ventilation frequency (ovf) was significantly (p<0.05) higher in exposed fish than control group frequency. Comparison with values of the control and values of fish from creeks (fish source) revealed haemoglobin, RBC, WBC, and PCV of the effluent treated fish to be significantly (p<0.05) decreased. The decrease in MCHC value was not significant (p>0.05) whereas MCV and MCH increased significantly (p<0.05) in the affluent treated fish. Based on results obtained from this work, it is recommended that effluent be treated before discharge in the receiving waters.
This study has established for the first time the acute toxicity of tannery effluents on C. gariepinus, an economically important fish found and exploited in Nigerian freshwater environments. Previously, Gbem et al. (1997) established that tannery effluents were toxic to O. niloticus, another economically important freshwater fish in Nigeria. The tested effluent had several physicochemical parameters higher than the recommended standards. Primary and secondary treatment has to be undertaken to cut down the pollution levels of the effluent before discharge into the environment.