Mangrove pneumatophore arthropod assemblages and temporal patterns

Abstract

Arthropod assemblages comprising mites, crustaceans and hexapods are characterized here for mangrove pneumatophores in south-eastern Africa. Initial sampling showed that pneumatophore assemblages differed markedly from benthic sediment assemblages, not only in being more species rich, but also in having lower abundances. Differences among pneumatophore arthropod assemblages were observed in comparisons of two mangrove stands (in the Durban region) and habitats within each stand. Strikingly higher arthropod abundances were found in assemblages associated with pneumatophores on the seaward fringes of the mangrove stands, as compared to those situated inside the mangrove stands or along minor waterways. These differences in abundance are ascribed to differences in physical conditions among habitat types, relating to wetting frequency and sunlight exposure. The assemblages associated with minor waterways varied among themselves according to variations in salinity. Temporal variation in abundance showed that some species peaked in summer and others in winter, indicating effects more closely related to terrestrial seasonal patterns, than to seawater temperature. This study highlights the uniqueness of the mangrove pneumatophore arthropod assemblages, and the need for further investigation into these in order to better understand mangrove meiofaunal ecology.