A preliminary fish survey of the estuaries on the east coast of South Africa, Mpande to Mtentwana: a comparative study

Abstract

A preliminary ichthyofaunal and physico-chemical survey of estuaries on the east coast of South Africa from the Mpande Estuary to the Mtentwana Estuary was undertaken between November 1997 and January 1998. Sixteen estuaries were surveyed along this stretch of coastline and these were grouped into three estuary types: small (< 10 ha) predominantly closed estuaries, moderate to large (> 10 ha) predominantly closed estuaries and predominantly open estuaries. Multivariate analyses revealed significant differences between the three groups in terms of both their physico-chemical characteristics (small predominantly closed estuaries were different from predominantly open estuaries) and their fish communities (all three estuary types were significantly different). The estuaries in the study area fall within the subtropical/warm-temperate transition-zone and north of the subtropical/warm-temperate biogeographic break; tropical species dominated the fish communities of all the estuaries in terms of numbers of species and biomass. This survey represents one of the few fish surveys undertaken along this little-studied section of the coastline.