Arctic calcifiers are believed to be particularly vulnerable to ocean acidification as the Arctic already experiences low carbonate saturations states due to low temperature and high inputs of freshwater. Here, we report the finding of dense beds of Mytilus growing in tidal lagoons and river mouths, where the availability of carbonate ions is remarkably low Ω_arag < 0.5. Although these Mytilus grow in the intertidal zone, and therefore are covered by seawater during high tide, δ¹⁸O isotopes of shell carbonate were low − 2.48 ± 0.05‰, confirming that their shells were deposited under low salinity conditions, i.e., reflecting a contribution from ¹⁸O-depleted freshwater. δ¹⁸O isotopes of shell carbonate became heavier with increasing salinity, with mean values of − 0.74 ± 0.96‰ for Mytilus growing in tidal pools. We calculated, based on δ¹⁸O isotopic composition standardized to a common temperature, that freshwater accounted for 7% of the carbonate oxygen in the shells of Mytilus at the habitats with near full-strength seawater salinity compared with 25% in shells collected at sites temporarily exposed to freshwater. The composition of the periostracum revealed a trend for shells from river mouths and brackish tidal lagoons to be more depleted in polysaccharides than shells exposed to higher salinity. We conclude that the high food supply associated with riverine discharge allows Mytilus to cope with the low saturation states by using energy to calcify and modify their periostracum to protect the shells from dissolution. These findings suggest that Arctic Mytilus are highly resistant to low saturation states of carbon minerals if supplied with sufficient food.

中文翻译：

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受到淡水影响的格陵兰岛沿岸的致密Mytilus床：在高食物供应下对腐蚀性水的抵抗力

人们认为北极钙化剂特别容易受到海洋酸化的影响，因为由于低温和淡水的大量投入，北极已经经历了低碳酸盐饱和状态。这里，我们报告的致密床的发现紫在潮汐泻湖和河口，其中碳酸根离子的可用性是非常低的生长Ω _ARAG  <0.5。虽然这些紫在潮间带长，因此，通过在涨潮海水覆盖，δ ^18个壳碳酸盐的氧同位素是低- 2.48±0.05‰，证实它们的弹，低盐度条件下，即下沉积，反映了贡献从¹⁸ O耗尽的淡水中提取。δ ¹⁸壳层碳酸盐的O同位素随着盐度的增加而变重，潮汐池中Mytilus的平均值为-0.74±0.96‰ 。我们计算的基础上，δ ¹⁸标准化为共同的温度氧同位素组成，即淡水占的壳碳酸盐氧气7％紫在与接近全强度海水盐度的栖息地与在地点收集壳25％相比暂时暴露在淡水中。骨膜的组成表明，河床和咸淡水泻湖中的贝壳比暴露于更高盐度的贝壳中的多糖消耗更多。我们得出的结论是，与河流排放有关的大量食物供应使Mytilus通过使用能量来钙化和修饰其骨灰质以保护壳免受溶解，从而应对低饱和状态。这些发现表明，如果食用充足的食物，北极Mytilus可以高度抵抗碳矿物质的低饱和状态。