Article: Faunal response to the instability of reef habitats: Pleistocene molluscan assemblages of Aldabra Atoll

Coral ecosystems are considered by many biologists to have been stable over ecological and evolutionary time, yet the Pleistocene history of reefs reveals complex and large-scale habitat changes associated with glacio-eustatic rise and fall of sea-level. Study of the molluscan assemblages from three Pleistocene rock units, together with faunas from Recent habitats on Aldabra Atoll, shows that shallow-water habitats and the associated communities have changed considerably during the period of the late Pleistocene. The communities inhabiting the shallow water of Aldabra today are very different from those of 125000 years ago, and the latter are in turn different from those of two older Limestones.Habitat and faunal changes of a similar magnitude are known or can be predicted for many other reefs in the Indo-Pacific province, and it is clear that present-day habitats have been formed and occupied only during approximately the last 3000-5000 years. The high diversity of reef faunas seems to be associated with the long-term survival and stability of the species pool of the Indo-Pacific province and not with the stability of individual reef systems.