LATE CENOZOIC HISTORY OF CORAL REEF ECOSYSTEMS: NEW DATA FROM THE CARIBBEAN AND CORAL TRIANGLE

Understanding how shallow marine ecosystems respond to global-scale environmental change is notoriously difficult due to the complex dynamics of both environmental and biotic processes. However, long-term records of ecosystem responses can be extracted from the fossil record, and studies of past examples can provide useful information regarding modes and rates of change. Here we report on results obtained from analysis of new data resulting from integrated study of Late Cenozoic biota and environments from the Caribbean and Coral Triangle region of Southeast Asia.

Over the past 25 years, Ann Budd and colleagues have been compiling a specimen-based occurrence data set with the goal of documenting the pattern of biotic and environmental change on Late Cenozoic Caribbean reefs. Recent advances in the taxonomy and stratigraphy require updating of the dataset, but do not significantly alter the observed pattern including a early Quaternary taxonomic extinction event in the Caribbean associated with widespread development of extensive reef building in the region. More recently, the Late Cenozoic record of the Coral Triangle has become available as a result of extensive new collecting in Indonesia and Malaysia. The modern coral reefs of the Coral Triangle are the most diverse on Earth, but understanding of the origins, maintenance, and ecological context for this diversity has been limited by a lack of information from the geological record of the region. The new data indicate that high diversity was present in range of habitats by the Late Oligocene, but that extensive reef framework was uncommon until the Late Miocene. The taxonomic composition of coral assemblages shows a marked shift during the Serravallian and Tortonian that is associated with the onset of modern carbonate regimes in the region that are characterized by extensive coral reef development.

These results suggest that the regional response of coral reef ecosystems to global environmental change is strongly modulated by regional conditions or that regional patterns are in fact largely forced by regional rather than global environmental changes. Therefore, attempts to understand long-term global patterns of diversity and ecosystem function as responses to global environmental change must include analysis of variation at regional to local scales.