Effect of sewage oxidation pond effluent on macroinvertebrate communities of a tropical forest stream, Nigeria

Abstract

The influence on aquatic macroinvertebrates of sewage oxidation pond effluent discharge was investigated in a tropical forest stream in Ile-Ife, Nigeria. A total of 858 individual macroinvertebrates were collected. They belong to 8 taxa which represent 5 orders. The number of taxa was low when compared to the findings in related water bodies suggesting a stressed ecosystem. There was a significant difference in the number of taxa between two sampling stations located upstream and downstream of the effluent discharge. Chironomid, ephemeropteran and odonate larvae were more abundant in downstream than upstream station. The preponderance of chironomids was attributed to environmental stress. It was suggested that predictions on impacts of sewage effluents should take cognizance of the natural changes in stream environment and organism life cycles.


Key words: Macroinvertebrates, oxidation ponds, sewage effluent, stream, stress ecology.


Journal of Aquatic Sciences Vol.17(1) 2002: 26-30