Abstract Quantitative profiles of stable isotopes and trace elements in biogenic carbonates have received considerable attention for the purpose of reconstructing past temperatures. The relationships between temperature and the geochemical parameters of carbonates are often subject to both inter- and intraspecific variations, which critically impair the accuracy of temperature estimation. One of the issues that must be addressed to improve temperature estimation is enhancing our understanding of the influence of the kinetic effect. This effect matters because the purely thermodynamic effect to geochemical profiles cannot be effectively separated from the effect of temperature-driven calcification rate. Cowries (Mollusca, Gastropoda, Cypraeidae) may provide a good model system for quantitatively investigating these two effects, because they undergo a callus-building stage in which aragonitic shell formation exclusively occurs to monotonically increase the thickness outward. We reared a total of 230 juvenile individuals of Monetaria annulus under six constant thermal regimes, ranging from the minimum growing temperature (21 °C) to the maximum tolerated long-term temperature (34 °C). The portions of the shells built in the callus-building stage were analyzed to quantify isotopic and elemental compositions. Shell growth rate positively depended on temperature from 21 °C to 33 °C, but dramatically decreased at 34 °C, presumably because of high temperature stress. Nevertheless, the heat stress did not make any impact on the thermal dependences (and among-individual variabilities within the same temperature) of either δ18Oc or Sr/Ca. A linear relationship exists between temperature and the stable oxygen isotope value of the shells (δ18Oc) across the entire thermal range (n = 103), whereas the shell Sr/Ca ratio increased exponentially with increasing temperature (n = 227). These results strongly suggest that any chemical processes responsible for quantitative incorporation of 18O and Sr into aragonite crystals were not impacted by heat stress at temperatures up to 34 °C. Within-temperature residual correlations between shell growth rates and δ18Oc were weakly positive, which is compatible with a widely accepted hypothesis that carbonic anhydrase suppresses the kinetic effect in molluscs. Likewise, we found no association between shell growth rates and Sr/Ca, which rejected the possibility that faster CaCO3 precipitation caused the positive relationship between temperature and Sr/Ca. A large proportion of among-individual variability in shell Sr/Ca was caused by unspecified factors other than temperature. This makes it difficult to accurately estimate the past temperature by measuring the Sr/Ca value of a single shell specimen.

中文翻译：

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高温胁迫不会扭曲基于生物碳酸钙的地球化学温度计：稳定的氧同位素值和腹足动物壳的 Sr/Ca 比率对饲养温度的响应

摘要 为了重建过去的温度，生物碳酸盐中稳定同位素和微量元素的定量分布受到了相当多的关注。温度与碳酸盐地球化学参数之间的关系通常受到种间和种内变化的影响，这严重影响了温度估计的准确性。改善温度估计必须解决的问题之一是增强我们对动力学效应影响的理解。这种影响很重要，因为对地球化学剖面的纯热力学影响不能有效地与温度驱动的钙化率的影响分开。Cowries (Mollusca, Gastropoda, Cypraeidae) 可以提供一个很好的模型系统来定量研究这两种影响，因为它们经历了一个愈伤组织构建阶段，在这个阶段，文石壳的形成只发生在向外单调增加厚度。我们在六种恒定温度条件下饲养了总共 230 只 Monetaria 环幼体，温度范围从最低生长温度 (21 °C) 到最大耐受长期温度 (34 °C)。分析在愈伤组织构建阶段构建的壳部分以量化同位素和元素组成。壳的生长速率在 21 °C 到 33 °C 之间正依赖于温度，但在 34 °C 时急剧下降，可能是因为高温应力。尽管如此，热应力对 δ18Oc 或 Sr/Ca 的热依赖性（以及同一温度内的个体间变化）没有任何影响。在整个热范围 (n = 103) 内，温度与壳的稳定氧同位素值 (δ18Oc) 之间存在线性关系，而壳 Sr/Ca 比率随温度升高 (n = 227) 呈指数增加。这些结果强烈表明，任何负责将 18O 和 Sr 定量掺入文石晶体的化学过程都不受温度高达 34°C 的热应力的影响。壳生长速率和 δ18Oc 之间的温度内残余相关性呈弱正相关，这与广泛接受的假设相一致，即碳酸酐酶抑制软体动物的动力学效应。同样，我们发现壳生长速率与 Sr/Ca 之间没有关联，这否定了更快的 CaCO3 沉淀导致温度与 Sr/Ca 之间存在正相关关系的可能性。外壳 Sr/Ca 的个体间差异的很大一部分是由温度以外的未指定因素引起的。这使得很难通过测量单个壳试样的 Sr/Ca 值来准确估计过去的温度。