Understanding factors structuring zooplankton and macroinvertebrate assemblages in ephemeral pans

Abstract

• Understanding invertebrate communities might help us make conserve and better manage ephemeral habitats. • Copepods were the most dominant and abundant taxa in all pans. • Thirty-three macroinvertebrate taxa belonging to 12 orders were recorded from the pans. • Flood plain pans had a more diverse macroinvertebrate fauna different from that of endorheic pans. • Vegetation is important for invertebrate taxa distribution in the pans. Ephemeral aquatic ecosystems have a global distribution being most abundant in semi-arid and arid regions. Due to anthropogenic impacts threatening these environments, there is a need to understand various factors and processes structuring animal communities in these habitats. Macroinvertebrate and zooplankton assemblages were studied in different ephemeral (i.e. flood plain, large endorheic and small endorheic) pans in the south-eastern Lowveld of Zimbabwe in the wet season. Ten Cladoceran species, Calanoids and Cyclopoids taxa and thirty-three macroinvertebrate taxa were identified over the entire hydroperiod. Predator macroinvertebrates were the dominant taxa especially in endorheic pans. The pan categories differed significantly in both zooplankton and macroinvertebrates composition and richness, with zooplankton and macroinvertebrate taxa richness being high in flood plain pans. Conductivity, fish presence, hydroperiod, maximum depth, turbidity and vegetation cover played a major role in shaping both zooplankton and macroinvertebrate communities. The macroinvertebrate community assemblage reveals that small endorheic and flood plain pans represent extremes ends of the environmental gradient in the region while large endorheic pans represent an intermediate end.