Mangrove Swamps in South Africa

Abstract

Descriptions are given of several mangrove swamps in Natal and Ponoland. It is demonstrated that in many ways the southernmost of these are more typically zoned than the more northern and that the atypical zonation is due to the presence of sand which appears to restrict the growth of certain species, notably Bruguiera, Rhizophora and Ceriops. Under conditions where freshwater influence is strong Bruguiera predominates and grows to 20 m. Where the soil is well drained Lumnitzrea may reach low inter-tidal levels. It is clearly shown that where mangroves develop into a typical mangrove swamp they are accompanied by the same assemblage of animals and that these animals with few exceptions do not extend to the south of the southernmost mangrove swamps. Most of these exceptions are only loosely associated with the mangroves. The mangrove fauna, as such, is in fact a fauna of very sheltered marine shores and not an estuarine one, i.e. it is not a fauna characteristic of regions with a salinity gradient but of regions with a variable salinity.