Influence of environmental variables on plankton community composition in permanent and temporal pans in and around Hwange National Park, Zimbabwe

Abstract

This study investigated the effect of environmental variables on plankton community composition in temporal, natural and permanent, artificial pans and reservoirs in and around Hwange National Park, Zimbabwe. We sampled 30 pans over a period of 11 months, covering both dry and rainy seasons. In total, 43 phytoplankton species belonging to 37 genera and 56 zooplankton species belonging to 23 genera were recorded. Species richness and diversity decreased in both phytoplankton and zooplankton communities during the dry season, although this was more pronounced for zooplankton. During both the dry and wet months, diatoms and rotifers dominated the phytoplankton and zooplankton communities, respectively, in both permanent and temporal pans. Redundancy analyses showed water hardness, vegetation, conductivity and pH as the different environmental factors that influenced the phytoplankton community structure, but they changed with the seasons. Redundancy analysis also showed that the zooplankton community composition in permanent and temporal pans is partly determined by total organic carbon, ammonium, and total phosphorous and, to a lesser extent, pH and chlorophyll a. The land use patterns had no effect on plankton community composition. Cyanobacterial blooms were rare in these shallow tropical systems despite high nutrient concentrations and temperature. We discuss the role of constant flushing in artificial pans.