Full Length Research Paper

Impact of urban wastewaters on the diversity and abundance of the fish population of Ogba River in Benin City, Nigeria

E. E. Obasohan* and J. A. O. Oronsaye

Department of Fisheries University of Benin, P. M. B. 1154, Benin City, Nigeria.

Department of Animal Science, Ambrose Alli University, Ekpoma, Nigeria.

*Corresponding author. E-mail: ewaensohan@yahoo.com.

Accepted 24 February, 2009

The effects of urban wastewaters on the diversity and abundance of the fish population of Ogba River in Benin City, Nigeria were assessed and monitored at 5 sample stations between November 2007 and October 2008. The physico-chemical properties of the water were also monitored during the period. A total of 486 individual fishes made up of 26 different species were recorded, with Clarias macromystax (Clariidae), Malapterurus electricus (Malapteruridae), Xenomystus nigri (Notopteridae), Hemichromis fasciatus and Oreochromis niloticus (Cichlidae) being the dominant species. The water chemistry, fish species diversity and abundance at the study stations were different and were negatively impacted upon by urban wastewaters pollution. It was also revealed that the fish communities of the river were under stress and not in good condition. Consequently, a close monitoring of all effluent discharges and other probable stress-inducing factors in Ogba River is recommended.

Key words: Ogba River, Nigeria, municipal wastewaters, fish, impact assessment.