Preliminary assessment of the biogeography of fishes in South African estuaries

Abstract

The biogeography of the fishes of 42 South African estuaries was investigated using an extensive synoptic dataset collected over the period 1993–99. Fish species richness was low on the west (Atlantic Ocean) coast and high in estuaries on the east (Indian Ocean) coast. Endemic species dominated the systems on the west and south coasts, whereas species of tropical origin dominated estuaries on the east coast. Multivariate analyses indicated that those estuaries on the west and south-west coast were distinct from the remaining systems, which showed a gradation from estuaries on the south coast to those on the north-east coast. An analysis of similarities showed that three biogeographic regions could be delineated. A cool-temperate region extended from the Orange River, down the west coast and along the south-west coast to Cape Agulhas; a warm-temperate zone stretched from Cape Agulhas to just south of Port St Johns; and a subtropical region extended up the east coast from approximately Port St Johns.