δ18O analysis of Donax denticulatus: Evaluating a proxy for sea surface temperature and nearshore paleoenvironmental reconstructions for the northern Caribbean

To identify oxygen isotope (δ18O) values and associated sea-surface temperature (SST) in the northern Caribbean, 82 δ18O values from 3 modern and 11 prehistoric Donax denticulatus shells were sampled. First, we conducted X-ray diffraction (XRD) on several modern shells to confirm aragonite composition. After identifying the biomineralogical composition of the shell, we applied several δ18O-to-SST conversion equations and selected the most appropriate formula based on pairing modern isotopic data with SST during the time of collection. We then converted prehistoric isotopic values to SST estimates to reconstruct paleo-SST for nearshore waters off the island of Nevis in the northern Lesser Antilles. Our results indicate that prehistoric isotopic signatures are slightly more depleted than modern signatures, with estimated SST similar to modern conditions for the region. Our study demonstrates the potential for Donax denticulatus to serve as a reliable proxy for recording ambient SST and reconstructing local paleoecology of nearshore environments, important for examining a host of issues related to prehistoric settlement and island adaptations.