What boron systems in coral Porites lobata tell us?--Implications for Seawater pH Reconstruction

抄録

How habitat, long-term ocean warming and acidification affect coral calcifying fluid carbonate chemistry remains poorly understood, limiting our ability to assess coral susceptibility and reconstruct past ocean conditions. Boron isotopes (δ11B) and B/Ca ratios in Porites corals have been used to infer the pH of coral’s calcifying fluid (pHCF). While the extent to which these proxies capture seawater pH (pHSW) and carbonate chemistry remains uncertain, the boron systems in Porites corals appear sensitive to environmental pH variations and continues to be a major focus of coral geochemistry research. Here, we present seasonally resolved δ11B and B/Ca records from Porites lobata collected from Lanyu, Taiwan, spanning two intervals: 1975 - 1986, and 2006 - 2021. We compare these results with published records from the same species to assess how environmental and physiological factors influence boron system in Porites lobata.Our results show a narrower and lower range of dissolve inorganic carbon (DIC) concentrations in the calcifying fluid of P. lobata, suggesting distinct external DIC supply or utilization compared to other Porites species. We also observed significant declines in pH