[U-02] 人新世・第四紀の気候および水循環

[U02-P04] Response of Coral Calcification to Rapid Ocean Acidification in the South China Sea Over the Past 42 years

*Kuo-Fang Huang¹、Hong Yi Chen¹ (1.Institute of Earth Sciences, Academia Sinica)

キーワード：Coral calcification, Ocean acidification, Boron isotopes, South China Sea, Dongsha Atoll

Ocean acidification (OA) threatens coral calcification by reducing carbonate ion concentration that corals need to build their skeletons. However, assessments of the impacts of long-term OA are scarce, limiting our understanding of the response and acclimatization of corals to high pCO₂ level. Here we present a 42-year (1968-2010) Porites coral δ¹¹B and B/Ca records from Dongsha Atoll (DSA), the northern South China Sea (NSCS) on seasonal basis, and the results suggest that the physiological modulation of pH_cf up-regulation in DSA corals not only minimizes seasonal variations in Ω_cf and maintains stable year-round calcification rates but also aids in long-term resistance to the adverse effects of OA. A rapid decline of pH_sw (-0.0021 ± 0.0008 pH unit/year) in the NSCS is observed during this period, and the long-term variability in pH_sw is primarily co-regulated by hydrological changes in the Pearl River and variations in the strength of Kuroshio intrusion, which can be linked to the interannual to decadal and large-scale climatic influences, such as Pacific Decadal Oscillation, El Nino-Southern Oscillation, and East Asian Winter Monsoon, in the NSCS.