Temporal variation of the plankton communities in a small tropical reservoir (Malilangwe, Zimbabwe)

Abstract

ABSTRACT Seasonal variations of plankton, expressed in terms of species composition and cell density in relation to selected physicochemical water parameters, were investigated in Malilangwe reservoir, Zimbabwe, between February and October 2011. In total, 98 phytoplankton species (2 Dinophyta, 4 Euglenophyta, 14 Bacillariophyta, 50 Chlorophyta, 13 Desmids and 15 Cyanophyta), 66 zooplankton species (13 Cladocerans, 7 Calanoids/Cyclopoids, 46 Rotifers) and two others (Chaoborus sp. and Hydracarina) were recorded. Chlorophyta, Dinophyta and Cyanophyceae comprised the bulk of the phytoplankton, while Rotifera and Cladocera dominated the zooplankton community. A typical seasonal succession of plankton species occurred from February to October. Algal blooms were observed during May to July, dominated by Anabeana sp., Nostoc sp., Anabeana circinalis, Zygenema sp., Anabeana sporiodes, Ceratium hirudinella and Perinidium sp. Redundancy Analysis (RDA) showed that water level, conductivity, pH, dissolved oxygen, temperature, reactive phosphorus and macrophyte cover accounted for most of the distribution of the plankton species.