ASSESSMENT OF RIVER HEALTH USING BENTHIC MACROINVERTEBRATES IN THE GROOT LETABA RIVER, SOUTH AFRICA

The Groot Letaba River catchment in South Africa, is known for agricultural activities, such as citrus and avocado farming. These activities are causing degradation of the river, especially near areas of commercial farming and human settlements. Benthic macroinvertebrates are good water quality bioindicators and are used to assess the health of aquatic ecosystems. The current study assessed river health of the river using macroinvertebrate community structure in relation to environmental variables. The macroinvertebrates were distributed among 42 families and 13 orders. The results revealed distinct spatial variation among the sampling sites and their associated macroinvertebrate communities, with the downstream having the least taxa richness and most of the tolerant taxa. The family richness and diversity were higher in the upstream and midstream sites. The changes in macroinvertebrate assemblages were primarily due to changes in water quality as a result of environmental factors, such as total dissolved solids (TDS), conductivity, dissolved oxygen and total nitrogen, and organic matter from agricultural activities.