Diversity patterns of temporary wetland macroinvertebrate assemblages in the south-western Cape, South Africa

Although macroinvertebrates are potentially useful for assessing the condition of temporary wetlands, little is yet known about them. Macroinvertebrate assemblages were assessed in 138 temporary wetlands in the south-western Cape, recording 126 taxa. However, predicted richness estimates were all higher than the observed richness. Five new species were collected-three hydraenid beetles, one streptocephalid fairy shrimp and one hydryphantid acarine-indicating the current paucity of knowledge about temporary wetland macroinvertebrates. The occurrence of the invasive snail Aplexa marmorata (Physidae) in this region was recorded for the first time. Assemblages were dominated by a few widespread taxa. Only four out of 73 genera accounted for more than half the total relative abundance and only two of these occurred in more than half the wetlands. Vegetated biotopes supported a higher relative abundance than open-water biotopes, but no difference existed between wetlands with one, two or three biotopes, indicating the conservation potential of wetlands with homogeneous biotopes. Wetlands from the different wetland regions did not show a clear separation based on their assemblage composition.