Cumulative impact of effluents on plankton dynamics in Awba Reservoir, Ibadan

Abstract

The assessment of changes in the biological community of water is a very sensitive measure of its quality. The plankton community structure of Awba reservoir in the University of Ibadan, Nigeria was monitored between April and October 1989 to determine the impact of natural eutrophication and effluent discharge on its dynamics. Generally, the dissolved oxygen content, pH, conductivity and ammonia-nitrogen values indicated a deterioration in water quality at stations receiving organic or chemical effluents. The plankton structure was characterized by a blue-green algae - Protozoa dominated community. The Simpson's diversity index at all stations was less than one implying a heterogeneous community where a few species dominated.

Tropical Freshwater Biology VOL. 8 1999, pp. 1-15



KEY WORDS:

effluents - water quality - Simpson's diversity index - plankton community structure