PLIO/PLEISTOCENE REEF DEVELOPMENT IN THE SOUTHERN DOMINICAN REPUBLIC: THE RISE OF ACROPORA DOMINANCE AND THE EMERGENCE OF MODERN CARIBBEAN REEFS

Prior to recent mass mortalities acroporid corals were the dominant component of Caribbean coral reefs dating back to at least the middle Pleistocene. The persistence of Acropora has provided a model for ecologic locking, and a basis for sea level and climatic reconstructions. The collapse of Acropora has generated a sense of alarm amongst ecologists. Insights into the stability and persistence of Acropora reefs may be revealed from the climatic and paleoecologic conditions under which Acropora rose to dominance in the Caribbean. However, the nature of Caribbean zooxanthellate reef communities between 500 Ka and at the least 1.2 Ma is virtually unknown. This gap in our understanding of Caribbean reefs is longer than the Middle Pleistocene to Recent record of Acropora dominance. Coastal reef terraces in the southern Dominican Republic fill this gap in the evolutionary/ecological transition to modern reef corals and record an associated change in the geometries and facies distributions within these reefs. Through examination of terrace exposures, building excavations and existing core material we provide an assessment of fringing reef development from the Plio/Pleistocene to recent of the southern Dominican Republic that integrates chronostratigraphic and sequence stratigraphic models with paleocologic changes in dominant reef builders. The coastal terrace deposits of the Dominican Republic record the transition from Sylophora dominated reefs to Acropora dominated reefs and provide insights into how fringing reefs respond to global sea-level cycles and Pleistocene climatic changes.