Abstract The ratios of barium to calcium (Ba/Ca) in reef coral skeletons have been used as a proxy to reconstruct temporal change in barium concentration in surface ocean. To reduce the uncertainty of the coral Ba/Ca proxy, the Ba distribution coefficients between seawater and coral skeletons were determined under different light conditions. Coral planulae (Acropora tenuis) were metamorphosed and settled in dishes with commercial peptide Hym-248 in the laboratory. Juvenile corals were infected with symbiotic algae (Durusdinium sp.) and cultured in 5 Ba concentrations (5, 10, 20, 35, and 150 μmol/mol) for 2 months. Half of the dishes were placed under low light conditions (10–33 μmol m-2 s−1), and another half of the dishes were placed under high light conditions (67–84 μmol m-2 s−1). The Ba/Ca ratios in the coral skeletons were highly correlated with those in ambient seawater under both high and low conditions (R2 > 0.8). The Ba distribution coefficients between seawater with 5–35 μmol/mol of Ba concentration and coral skeletons were 0.72 and 2.83 under high and low light conditions, respectively. These results suggest that biological processes related to light availability could influence to Ba/Cacoral.

中文翻译：

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光对珊瑚骨骼中 Ba/Ca 比率的影响

摘要 礁珊瑚骨骼中钡与钙的比率 (Ba/Ca) 已被用作重建表层海洋中钡浓度随时间变化的替代指标。为了减少珊瑚 Ba/Ca 代理的不确定性，在不同的光照条件下确定了海水和珊瑚骨架之间的 Ba 分布系数。珊瑚扁平（Acropora tenuis）在实验室中用商业肽 Hym-248 变形并固定在培养皿中。幼珊瑚被共生藻类 (Durusdinium sp.) 感染，并以 5 Ba 浓度（5、10、20、35 和 150 μmol/mol）培养 2 个月。一半的培养皿置于弱光条件下（10-33 μmol m-2 s-1），另一半培养皿置于强光条件下（67-84 μmol m-2 s-1）。珊瑚骨骼中的 Ba/Ca 比率与高和低条件下（R2 > 0.8）的环境海水中的比率高度相关。Ba浓度为5-35μmol/mol的海水与珊瑚骨架在高光和低光条件下的Ba分配系数分别为0.72和2.83。这些结果表明，与光照相关的生物过程可能会影响 Ba/Cacoral。