The Intertidal fish fauna of the west coast of South Africa — species, community and biogeographic patterns

Abstract

In the first quantitative survey of intertidal fish from the South African west coast 62 intertidal rock pools were sampled at two sites, using the ichthyocide rotenone. A total of 2 022 fish representing 14 species belonging to only two families — the Clinidae (88–98% by number) and the Gobiesocidae (12–2%) — were caught. Clinus superciliosus, C. heterodon and the gobiesocid Chorisochismus dentex were the most abundant species in terms of both numbers and biomass. Vertical zonation of individual species on the shore indicated little separation of the habitat between species, although some species exhibited size-specific partitioning of the shore. Relationships between fish distribution and abundance and rock pool characteristics were elucidated by means of stepwise multiple regression, both at the whole community and individual species levels. The abundances of individual species were best predicted by pool size, although some species also showed an association with weed cover. For the community as a whole, the number of species present, the total number of fish and the total biomass in any pool were all dependent on pool size, height above LWS and amount of available cover. Relative to other South African sites the west coast has a low diversity of intertidal fish, combined with a high degree of dominance and a low level of habitat separation.