Application of Paleoclimatology to Coral Reef Monitoring and Management

The skeletons of reef-building corals are valuable archives of climatic and environmental information. Paleoclimatic data chiefly have been generated in areas most sensitive to global or regional climatic variability. However, these records also provide valuable information on anthropogenic influences – guidance of value to resource managers. NOAA’s Coral Reef Watch targets observations of current and past coral reef health in or near marine protected areas through satellites, in situ sensor platforms, and paleoclimatic analyses. Paleoclimatic data provide retrospective monitoring through multi-century environmental reconstructions that improve our understanding of past stress to coral reefs. Two sites in the Florida Keys National Marine Sanctuary were the first to benefit from Coral Reef Watch Program paleoenvironmental analyses. Coral cores yielded direct measurements of δ18O, δ13C, Sr/Ca, and coral skeletal growth (extension, density, and calcification) and reconstructions of reef temperatures. Temperature reconstructions were compared with instrumental data from nearby stations and global data sets, while skeletal growth was used to infer responses to changing climatic and environmental conditions. Differences between paleoclimatic data and gridded datasets demonstrated that paleodata provide more accurate estimates of reef temperatures as they sample subsurface temperatures where the corals live. Because of relatively high thermal variability, at least 12 samples per year are needed at these sites. Further work will extend these records back in time, to new locations, and expand on the data reconstructed from the skeletal archives.