The intertidal fish fauna of the west coast of South Africa - species, community and biogeographic patterns

ENGLISH 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. *********** AFRIKAANSE OPSOMMING: Tussengety-visspesies aan die Suid-Afrikaanse weskus is vir die eerste keer kwantitatief versamel uit 62 getypoele in twee areas met behulp van die visdoder rotenone. 'n Totaal van 2 022 visse wat 14 spesies, maar slags twee families verteenwoordig - die Clinidae (88-98% van die totale aantal) en die Gobiesocidae (12-2%) - is gevang. Clinus superciliosus, C. heterodon en die suiervis, Chorisochismus dentex, was die mees talryke spesies beide met betrekking tot getalle en biomassa. Vertikale indeling van individuele spesies in die tussen getysone het op min verdeling van die habitat tussen spesies gedui, alhoewel sommige spesies 'n verdeling in terme van grootte vertoon het. Verwantskappe tussen die verspreiding en talrykheid van visse, en die kenmerke van rotspoele is blootgele deur middel van stapsgewyse veelfaktor-regressie vir die hele gemeenskap sowel as vir individuele spesies. Die talrykheid van individuele spesies is die beste voorspel deur poelgrootte, alhoewel sommige spesies ook geassosier is met die wierbedekking. Vir die hele gemeenskap was die getal visspesies en induvidue en die totale biomassa in enige poel almal afhanklik van poelgrootte, hoogte