Community composition and distribution of macroinvertebrates in the Umzimvubu River, South Africa: a pre-impoundment study

  • BR Makidizela Resource Quality Services (Institute for Water Quality Studies), Department of Water Affairs and Forestry, Private Bag X313, Pretoria 0001, South Africa
  • AH Dye Centre for Research on Ecological Impacts of Coastal Cities, Marine Ecology Laboratories, University of Sydney, Sydney, New South Wales 2600, Australia


This paper presents baseline biological data on aquatic macroinvertebrates and water quality in the Umzimvubu River and selected tributaries, Eastern Cape Province, South Africa, prior to the construction of proposed large-scale water resource developments. Sampling was conducted seasonally at 14 sites between 1996 and 1998. The macroinvertebrate community composition was strikingly similar (±70%) across sites. Faunal diversity was low (104 taxa in total), but many taxa found were sensitive to water quality change (ASPT 5.0 to 9.6), indicating good water quality, which is attributed to the currently undeveloped nature of the catchment. Concentrations of water quality variables fell within a narrow range, except for total suspended solids, which at times was very high (up to 8 532mg l–1). The highly variable concentration of the total suspended solids and its potential effects on biodiversity need to be investigated further. It is likely that bilharzia will spread and that pest blackflies may become a problem to livestock if the water resources become developed as is proposed. We suggest that more flow gauging weirs are needed to measure flows better for future management and also that the implications of the proposed developments on the estuary need to be investigated.

Keywords: environmental reserve; SASS4; total suspended solids; Umzimvubu River; Eastern Cape; South Africa

(Afr J Aqua Sci: 2003 28(2): 137-149)

Journal Identifiers

eISSN: 1727-9364
print ISSN: 1608-5914