Bioassessment of the ecological integrity of river ecosystems using aquatic macroinvertebrates: an overview with a focus on South Africa

An overview is given of the bioassessment of the ecological integrity of river ecosystems using aquatic macroinvertebrates, focussing on the South African situation within a global context. Biotic indices and their use in aquatic bioassessment are covered, and comparative descriptions of the more important and/or widely used macroinvertebrate-based biotic indices are given. For each biotic index described, information is provided on the biotopes sampled, the sampling equipment used, the sampling protocol followed, the level of taxonomic resolution, whether identifications are laboratory- or field-based, the range of the final index value, and its current usage. A discussion on using biotic indices and interpreting bioassessment data follows. The multimetric and multivariate approaches to bioassessment are compared, as are the regional and multivariate approaches to the derivation of reference conditions. The use of invertebrate habitat assessment in river bioassessment studies is briefly discussed and the South African spatial framework for analysing bioassessment data is described. In conclusion, a number of potential avenues for further research regarding the use of macroinvertebrates in the bioassessment of river ecosystems are identified.