NOAA/WDS Paleoclimatology - Palaui Islands, Philippines Diploastrea heliopora and Porites lobata Sr/Ca and d18O Data from 1954 to 2012

The Indo-Pacific coral Diploastrea heliopora reveals regional multi-decadal to centennial scale climate variability using coral carbonate d18O (d18Oc) as a combined proxy for sea surface temperature (SST) and sea surface salinity (SSS). However, to assess the coral’s full potential in resolving climatic events, an independent SST proxy would be more advantageous. We examined both Sr/Ca and d18O of Diploastrea against an adjacent Porites lobata core collected from northeast Luzon, Philippines. Winter Sr/Ca data from Diploastrea show a significant correlation to SST (r = -0.41, p < 0 .05, RMSR = 0.81°C) and provide a proxy with similar sensitivity as Porites (r = -0.57, p < 0.05, RMSR = 0.62°C). An inter-species SST record is shown to be robust and used for a reconstruction of the Pacific Decadal Oscillation (PDO) during boreal winter (r = -0.70, p = 0.02). While we were unable to generate a robust Diploastrea d18O-SSS calibration at inter-annual timescale, the freshening trend towards the present, commonly observed in the region, is qualitatively captured in Diploastrea d18O. Comparison with Porites d18O and instrumental SSS records shows that the magnitude of freshening is consistent between coral species. Wet and dry season Porites d18O provide support for the relative influence of El Niño Southern Oscillation (ENSO) events and local precipitation to SSS variability at our site. The multi-proxy, multi-species approach of this study further strengthens the evidence for Diploastrea as an alternate climate archive in the Indo-Pacific region, and seals its potential in helping resolve less understood global-scale climate phenomena.