Climate signal recording ability of Isopora corals: SST reconstruction during the LGM in the Great Barrier Reef and testing by coral culture experiment

Abstract

Fossil Isopora corals were dominant in the interval corresponding to the Last Glacial Maximum in a drill core from the Great Barrier Reef obtained by the Integrated Ocean Drilling Program Expedition 325 (Webster et al., 2011; Yokoyama et al., 2011). Direct application of modern coral Sr/Ca-SST relationship gave an estimate of LGM SST ???????????4?6 °C cooler than today at the northern GBR (17°S) (Felis et al., 2014). In order to test climate signal recording ability of Isopora corals, we cultivated I. palifera clone colonies at five different temperatures for testing the utility of its skeletal oxygen isotope ratio as a paleotemperature proxy (Nishida et al., 2014). The skeletal oxygen isotope ratio of the specimens cultured at 21?30°C correlated strongly with water temperature, and temperature sensitivity was ?0.15⁰/₀₀/°C. Thus, the skeletal oxygen isotope ratio of I. palifera corals can be a good temperature proxy at temperatures below 30°C.