DISTRIBUTION PATTERN OF MACROINVERTEBRATE FUNCTIONAL FEEDING GROUPS IN THE STEELPOORT RIVER, SOUTH AFRICA

The various human activities along the Steelpoort River in South Africa are causing changes in water quality and affecting the distribution of macroinvertebrate functional feeding groups (FFG). The objectives of this study were to assess the spatial and temporal distribution of FFG of macroinvertebrates and to determine if the community structure corresponds to the River Continuum Concept (RCC). The distribution of the FFG varied significantly among sites and the variation was related to the different characteristics of the sites. The collector-gatherers were the most abundant functional feeding group at Site 1, collector-filterers were the most dominant group at Site 4 and Site 5, predators were the most dominant group at Site 2, Site 3 and Site 6. Shredders were least represented at all sites of the river. Seasonally, the collector-gatherers were dominant in winter, collector-filterers were dominant in spring and predators were the dominant group in autumn and summer. The study showed that the distribution of FFG was not in conformity to the RCC. The results suggest that land use changes in the catchment is affecting the FFG distribution pattern. It is therefore important that policies governing land use changes should take into account the impact on the macroinvertebrate community.