The ecological impact of stream regulation using benthic macroinvertebrates as indicators

Abstract

A study of the benthic macroinvertebrates of a fourth order stream in southern Nigeria was carried out to assess the ecological impact of stream regulation. Three stations, 1, 2, and 3 were selected from upstream of the impoundment, the impoundment (reservoir) and it's downstream respectively. Among the physical and chemical parameters studied, only the water level, transparency, current velocity and dissolved oxygen were significantly different (P<0.05) among the study stations. Of the 43 benthic macroinvertebrate taxa recorded, the overall density of fauna was not significantly different among the three stations. The density of the three dominant taxonomic groups, Diptera, Oligochaeta and Ephemeroptera differed significantly (P<0.05) among the stations. Analysis of faunal similarities showed that the upstream station 1 was significantly different from stations 2 and 3. Stream regulation therefore alters not only the river hydrology but also the faunal characteristics of downstream stations.




JOURNAL OF AQUATIC SCIENCES Volume 16, Number 2, October 2001, pp. 132-138