Anthropogenic CO₂-emission is causing ocean warming and acidification. Understanding how basic physiological processes of marine organisms respond to these stressors is important for predicting their responses to future global change. We examined the effects of elevated pCO₂ and temperature (pCO₂ = 344–2199 ppm; temperature = 6°C, 9°C, and 12°C) on the calcification rate, extrapallial fluid (EPF) carbonate chemistry, respiration, and survivorship of Atlantic sea scallops (Placopecten magellanicus) in a fully crossed 143-d experiment. Rates of calcification and respiration were inhibited by elevated pCO₂, and mortality occurred when elevated pCO₂ was accompanied by high-temperature stress. Declines in growth and survivorship were likely caused by external shell dissolution, thermal stress, and hypercapnic reduction of metabolism under elevated pCO₂. Concentrations of dissolved inorganic carbon (DIC) and total alkalinity in the EPF increased above seawater concentrations in response to elevated pCO₂. EPF pH declined, but did not decline as much as seawater pH, indicating that scallops regulate EPF pH to support calcification. The combination of EPF pH regulation and DIC elevation yielded an increase in EPF [${\mathrm{CO}}_3^{2-}$] under elevated pCO₂ treatments. The combination of low respiration rates, high EPF [${\mathrm{CO}}_3^{2-}$], and low calcification rates under elevated pCO₂ suggests that the impaired calcification arises more from hypercapnic inhibition of metabolic activity and external shell dissolution than from chemically unfavorable conditions in the EPF. These results demonstrate the importance of EPF chemistry for bivalve biomineralization, but show that regulation efforts are insufficient to fully offset the deleterious effects of elevated pCO₂ on scallop performance.

中文翻译：

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升高的 pCO2 和温度对大西洋扇贝 Placopecten magellanicus 钙化率、存活、外液化学和呼吸的影响

人为 CO ₂排放导致海洋变暖和酸化。了解海洋生物的基本生理过程如何对这些压力源作出反应对于预测它们对未来全球变化的反应非常重要。我们检查了升高的 pCO ₂和温度（pCO ₂  = 344–2199 ppm；温度 = 6°C、9°C 和 12°C）对钙化率、外层流体 (EPF) 碳酸盐化学、呼吸和在完全交叉的 143 天实验中，大西洋扇贝 ( Placopecten magellanicus ) 的存活率。_{pCO 2}升高会抑制钙化和呼吸的速率，当 pCO ₂升高时会发生死亡率伴随着高温胁迫。生长和存活率的下降可能是由外壳溶解、热应激和 pCO ₂升高下代谢的高碳酸血症减少引起的。_{响应于 pCO 2}升高，EPF 中溶解的无机碳 (DIC) 浓度和总碱度高于海水浓度。EPF pH 值下降，但没有海水 pH 值下降那么多，表明扇贝调节 EPF pH 值以支持钙化。EPF pH 调节和 DIC 升高的结合导致 EPF 增加 [${\mathrm{一氧化碳}}_3^{2-}$] 在升高的 pCO ₂处理下。低呼吸率、高 EPF [${\mathrm{一氧化碳}}_3^{2-}$_{]，而 pCO 2}升高下的低钙化率表明，钙化受损更多是由于高碳酸血症抑制代谢活动和外壳溶解，而不是 EPF 中的化学不利条件。这些结果证明了 EPF 化学对双壳类生物矿化的重要性，但表明监管努力不足以完全抵消 pCO ₂升高对扇贝性能的有害影响。