POTENTIAL IMPACT OF VARIATION IN THE SEAWATER STRONTIUM TO CALCIUM RATIO ON CORAL PALEOTHERMOMETRY IN THE FLORIDA KEYS, USA
Kilbourne, Kelly H
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Standard methods of reconstructing past sea surface temperatures with coral skeletal Sr/Ca ratios assume that the seawater Sr/Ca ratio is constant. However, data to support this assumption are sparse in coral reef environments, in part because analytical techniques capable of determining seawater Sr/Ca with sufficient accuracy and precision are time-consuming and not widely available. This work presents a new method to measure seawater Sr/Ca based on inductively coupled plasma atomic emission spectrometry that can be easily adopted by many coral paleothermometry laboratories. The work also presents a spatially gridded study of summer and winter seawater Sr/Ca from the middle Florida Keys Reef Tract. The results indicate that seawater Sr/Ca in nearshore waters influenced by the Florida Bay varies by ~0.1 mmol/mol. The observed variation could lead to errors of ~2°C in temperature reconstructions and suggests that corals growing in waters influenced by Florida Bay are less suited for paleoclimate studies.