RECENT LIFE AND DEATH CORAL ASSEMBLAGES ON THE FLORIDA REEF TRACT: COMPARISON WITH PALEOECOLOGICAL RECORDS

The purpose of the project was to evaluate what the effect of present-day life and death coral assemblages is on determining changes in coral reef community structure along the Florida Reef Tract through time and space. Data collected from both living and fossil reefs from the Florida Keys suggest that the taxonomic composition of reef corals preserved in the Key Largo Limestone more accurately represents the assemblage of corals currently living on the present day reef tract than the contemporary death assemblage. These data confirm the hypothesis that the present-day coral life assemblages are significantly different than their death assemblages on the Florida Reef Tract but similar to the coral assemblages preserved in the Pleistocene Key Largo Limestone. This similarity is due to the presence of massive coral species, especially those of the Montastraea, Diploria, and Porites species complex. These corals are rare in the death assemblages surveyed on the present-day Florida reefs but common in both the life and fossil assemblages. The major difference between the death assemblage and both the life assemblage and the fossil assemblage is the prevalence of the branching Acropora species in the death assemblage. Because of the dissimilarity in composition between modern life and death assemblages, the modern reef system is presently very different than it was in the recent past. The loss of acroporid corals has been the driving force in that transition. Interestingly, exposures of the Key Largo Limestone are the only known reefs of Pleistocene age from the Caribbean that are not dominated by acroporids. Thus, the fossil record provides a powerful tool for understanding the degree to which past changes can enhance our capacity to evaluate modern reef degradation.