A Comparative survey of reef-associated Gastropods at Maziwi Island, Tanzania

Abstract

The overall abundance and species diversity of gastropods at Maziwi Island was greater than that of any of the sites surveyed by the author at Diani Beach or Malindi Marine National Park in Kenya (Yaninek, 1976). The remote location of the reef is probably the single most important factor contributing to its relatively protected state. Even though most species of the family Conidae were not included in the previous survey, the species distributions and habitat preferences were similar to those observed at Maziwi Island. The species distributions observed at Malindi and Maziwi were similar, except for the occurrence of Pleuroploca trapezium at the former site, where it was dominant on Thalassodendron benches. Commercial collecting or "predation" on gastropods hits the rare species of a reef community, but in a naturally regulated community it is usually the most abundant species which receive the heaviest predation. Limiting human exploitation of the reef's resources would help restore stability to the community. Further quantitative studies along the East Mrican coast are needed to provide a basic understanding of the existing reef communities. These studies can result in the improvement of conservation measures since sound management policies can lead to a sustained yield of this natural resource.