Ecological health of the Usuthu and Mbuluzi rivers in Swaziland based on selected biological indicators

Abstract

Biological monitoring, using coliform bacteria and macroinvertebrate populations and diversity, was carried out monthly from August 2004 to January 2005 to determine the ecological health of the Usuthu and Mbuluzi rivers in Swaziland. Water temperature and pH were not significantly different between sites, but differed significantly between months. Bacterial species identified from both rivers were Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris , with no significant differences in mean colony counts between the two rivers. Average colony counts were significantly different between months. A total of 926 macroinvertebrates, representing 28 families, were collected from both rivers and were significantly different between sites, rivers and months. Macroinvertebrate populations and diversity were negatively correlated with bacterial colony counts. Compliance with regulated water quality standards did not necessarily indicate acceptable water quality for biological communities, and thus there is a need for an integrated approach in water quality monitoring.

Keywords: biological monitoring, coliform bacteria, macroinvertebrates

African Journal of Aquatic Science 2010, 35(3): 283–289