NOAA/WDS Paleoclimatology - Looe Key, Florida Coral Stable Isotope and Trace Metal Data from 1947-2002 CE

Monthly resolved, 41-year-long stable isotopic and elemental ratio time series were generated from two separate heads of Montastraea faveolata from Looe Key, Florida, to assess the fidelity of using geochemical variations in Montastraea , the dominant reef-building coral of the Atlantic, to reconstruct sea surface environmental conditions at this site. The stable isotope time series of the two corals replicate well; mean values of d18O and d13C are indistinguishable between cores (compare 0.70‰ versus 0.68‰ for d13C and -3.90‰ versus -3.94‰ for d18O). Mean values from the Sr/Ca time series differ by 0.037 mmol/mol, which is outside of analytical error and indicates that nonenvironmental factors are influencing the coral Sr/Ca records at Looe Key. We have generated significant d18O-sea surface temperature (SST) (R = -0.84) and Sr/Ca-SST (R = -0.86) calibration equations at Looe Key; however, these equations are different from previously published equations for Montastraea . Variations in growth parameters or kinetic effects are not sufficient to explain either the observed differences in the mean offset between Sr/Ca time series or the disagreement between previous calibrations and our calculated d18O-SST and Sr/Ca-SST relationships. Calibration differences are most likely due to variations in seawater chemistry in the continentally influenced waters at Looe Key. Additional geochemical replication studies of Montastraea are needed and should include multiple coral heads from open ocean localities complemented whenever possible by seawater chemistry determinations.