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

Abstract

We propose skeletal delta O-18 of Platygyra, a hermatypic reef building massive coral, as a potential paleo-SST proxy in mid-latitude regions, where the commonly used massive Porites corals are rare. Skeletal delta O-18 ratio (delta O-18(c)) 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 parts per thousand/degrees C (T = -4.57 delta O-18(c)+ 2.65, r(2) = 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 delta O-18(c), 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.