Preliminary studies on the occurrence of freshwater epipelic algae in the Densu basin in Southern Ghana

Abstract

The occurrence and composition of the freshwater algae in the epipelon were determined at three sites, namely Machigeni, Manhean and Weija, located in the coastal savanna thicket and grassland vegetation zone of the River Densu basin in southern Ghana. Samples of sediments from the water-substratum interface were taken at fortnightly intervals over 2 months at Machigeni, Manhean and Weija, in January 2008 and March 2008, and studied. The epipelic flora of River Densu exhibits high diversity, with the richest flora in Machigeni, followed by Manhean and Weija in that order. A total of 38 algal genera were identified over the period, with the Bacillariophyceae dominating with 19 genera followed by the Chlorophyta and the Cyanophyta with 13 and 6 genera, respectively. Fragilaria, Melosira and Rhizosolenia were the most abundant Bacillariophyta genera encountered. The Chlorophyta had Closterium, Pediastrum and Spirogyra, as the dominant genera. Anacystis and Oscillatoria had the highest number of cells among the Cyanophyta genera sampled.