A preliminary study of stable oxygen isotopic composition of the corals genus Porites from the Gulf of Thailand

Abstract

There are limited coral-based paleoclimate records in the Gulf of Thailand to date. Therefore, in this study we present preliminary data on the stable oxygen isotopic (σ 18 O) composition of the modern coral genus Porites from Samaesan and Ngam Islands. Two corals were analyzed that grew between 1997 and 2009 AD, and 1996 and 2010 AD, respectively. The annual growth rate was an average of 12.33 mm yr-1. Two σ 18 O profiles showed a good correlation in pattern and isotopic range. Correlational analyses indicated that coral σ 18 O is a robust proxy for the sea surface temperature (SST), which was supported by significantly negative correlations between skeleton σ 18 O and SSTs. These seasonal calibrations suggested a temperature dependence of 0.13 and 0.15 % °C -1 . The growth rate of one skeleton was positively correlated with its σ 18 O, but this relationship was not identified in the others, indicating an intercolony variability in the growth rate effect on σ 18 O. The short-term variations in El Niño-Southern Oscillation (ENSO) were faithfully recorded in coral σ 18 O, as observed in the correlations of coral σ 18 O with the Southern Oscillation Index (SOI) and SST during ENSO events. Based on these data, we suggest that the coral from the Gulf of Thailand could serve as a potential paleo-climate proxy in the future. © Research India Publications.