Reconstruction of the East China Sea palaeoenvironment at 16 ka by comparison of fossil and modern Faviidae corals from the Ryukyus, southwestern Japan

We conducted paired measurements of the Sr/Ca ratio and oxygen and carbon stable isotopes of a fossil Faviidae coral specimen (MYK90), age 16ka, collected from near Miyako Island, the Ryukyus, southwestern Japan. Our study aimed to reconstruct the palaeoenvironment in the East China Sea at 16ka by comparing the fossil sample with modern Faviidae corals. Our data with annual or longer time resolution may be very suitable for palaeoceanographic reconstruction, although no general calibration method for Faviidae corals has been reported. Our calibration showed that the annual mean sea surface temperature was approximately 58C lower and sea surface salinity (SSS) at the study site was locally higher at 16ka than at present. Even though the mouths of the Yellow and Changjiang rivers were east of their present locations because sea level was much lower, our results suggest that the influence of the terrestrial water discharge may not have extended to Miyako Island. Weak summer monsoon activity during the last glacial, which decreased summer precipitation over the Asian continent, and an enhanced winter monsoon, which may have led to more evaporation, likely contributed to the inferred high SSS at the study site.