Organisms, such as molluscs, that produce their hard parts from calcium carbonate are expected to show increased difficulties growing and maintaining their skeletons under ocean acidification (OA). Any loss of shell integrity increases vulnerability, as shells provide protection against predation, desiccation, and disease. Not all species show the same responses to OA, which may be due to the composition and microstructural arrangement of their shells. We explore the role of shell composition and microstructure in resisting dissolution caused by decreases in seawater pH using a combination of microCT scans, XRD analysis, and SEM imaging. Two gastropods with different shell compositions and microstructure, Tegula funebralis and Nucella ostrina, were exposed to simulated ocean acidification conditions for six months. Both species showed signs of dissolution on the exterior of their shells, but changes in density were significantly more pronounced in T. funebralis. XRD analysis indicated that the exterior layer of both shell types was made of calcite. T. funebralis may be more prone to dissolution because their outer fibrous calcite layer has more crystal edges and faces exposed, potentially increasing the surface area on which dissolution can occur. These results support a previous study where T. funebralis showed significant decreases in both shell growth and strength, but N. ostrina only showed slight reductions in shell strength, and unaffected growth. We suggest that microstructural arrangement of shell layers in molluscs, more so than their composition alone, is critical for determining the vulnerability of mollusc shells to OA.

预期由碳酸钙生产其坚硬部分的生物（如软体动物）在海洋酸化（OA）下生长和保持其骨骼的难度将增加。外壳完整性的任何损失都会增加脆弱性，因为外壳可提供保护，防止捕食，干燥和疾病。并非所有物种都对OA表现出相同的响应，这可能是由于其壳的组成和微观结构排列所致。我们使用microCT扫描，XRD分析和SEM成像相结合的方法，探索了壳成分和微结构在抵抗海水pH降低引起的溶解中的作用。两种具有不同壳组成和微结构的腹足类动物，例如Tegula funebralis和Nucella ostrina被暴露在模拟的海洋酸化条件下六个月。两种物种在其壳的外部都显示出溶解的迹象，但是密度的变化在T. funebralis中更为明显。XRD分析表明，两种壳类型的外层均由方解石制成。三角锥虫可能更易于溶解，因为它们的方解石纤维外层具有更多的晶体边缘和暴露的面，从而潜在地增加了可发生溶解的表面积。这些结果支持以前的研究，其中T. funebralis显示出壳的生长和强度均显着降低，但是N. ostrina仅显示出壳强度略有降低，且未受影响。我们认为，软体动物壳层的微观结构排列（比其单独组成更重要）对于确定软体动物壳对OA的脆弱性至关重要。