The ecology of sandy beaches in Transkei

Data from an ecological survey of three sandy beaches in Transkei and from Gulu beach on the eastern Cape coast, South Africa, are presented. Physical parameters such as beach profile, sand particle size, Eh and carbonate content, as well as abundance, composition, biomass and distribution of the macrofauna and meiofauna were investigated. Beaches in Transkei are relatively small and are usually associated with estuarine systems. Substrate at Thompson's beach in northern Transkei was relatively coarse with relatively few macrofaunal species. Further south, beaches have fine to medium substrates and are characterized by a diverse macrofaunal community. Major changes in faunal composition occurred in Transkei and this was most evident for Mpande and Cebe beaches where a subtropical east-coast fauna was replaced by species characteristic of the southern Cape coast. Molluscs also became increasingly important southwards and replaced crustaceans as the most important group. Meiofauna was dominated by nematodes and harpac- ticoids on all beaches and there was an increase both in numbers and biomass southwards.