Aquatic macroinvertebrate responses to pollution of the Boesmanspruit river system above Carolina, South Africa

Abstract

The upper Boesmanspruit river system received much attention in 2012 when a pollution event in January rendered the drinking water of the town of Carolina non-potable. The responses of aquatic macroinvertebrate assemblages in the upper Boesmanspruit system to that event were investigated in 2012–2013. Water quality was fair during the survey periods. Macroinvertebrate responses in the Witrandspruit, a tributary of the Boesmanspruit, showed slow recovery in the lower reaches and slight recovery in the upstream areas, demonstrating the intensity of the pollution event at the downstream sites and indicating continued toxicity. Overall, macroinvertebrate assemblage indices were modified and poor, representing recent and historical events within each river catchment. Despite a 15-month period of improved water quality after January 2012, the macroinvertebrate communities had recovered only slightly. Continued monitoring of macroinvertebrates in the study area is recommended, so as to investigate further the recovery periods of macroinvertebrates in the South African highveld.