BENTHIC MACROINVERTEBRATES AS BIOINDICATORS OF WATER QUALITY IN THE BLYDE RIVER OF THE OLIFANTS RIVER SYSTEM, SOUTH AFRICA

The Olifants River System and its catchment have been exposed to prolonged and cumulative ecosystem stress as a result of human settlements, mining, agricultural and industrial activities. The Blyde River is known to supply the Olifants River with water of good quality and quantity. However, theintensive farming and human settlements in the catchment could threaten the river. The aim of the study was to assess the water quality of the Blyde River in South Africa using aquatic macroinvertebrates as bioindicators. Seven sites along the river were selected for sampling. The family composition, based on abundance and diversity was evaluated in relation to environmental variables. The results of some measured physicochemical parameters revealed that water quality of the Blyde River is not significantly altered and the presence of ecologically sensitive macroinvertebrates was an indication of good water quality as this benthic fauna was well represented in all seasons and most parts of the river. The study therefore has indicated that the river was inhabited by a healthy macroinvertebrate community suggesting that the water is still of good quality.