High resolution stable isotope records of sclreractinian corals near Ishigaki Island: Their implication as a potential paleoclimatic recorder in middle latitude regions

摘要

We propose skeletal δ18O of Platygyra, a hermatypic reef building massive coral, as a potential paleo-SST proxy in midlatitude regions, where the commonly used massive Porites corals are rare. Skeletal δ18O ratio (δ18Oc) of a Platygyra and Porites corals collected from Ishigaki Island, Japan, shows a clear seasonality corresponding to SST variation. The temperature dependence of the Platygyra coral was estimated, for the first time with appropriate sampling resolution, at ?0.219‰/°C (T = ?4.57δ18Oc + 2.65, r2=0.96). Massive Platygyra colonies show a wide distribution from the tropics to mid-latitudes further northwards than Porites. Platygyra’s adaptation to colder water temperatures and strong temperature dependence of δ18Oc suggest its application as a potential paleo-SST proxy for mid-latitude regions, where high resolution SST proxies are not available, as well as in tropical to subtropical regions.