Ocean higher temperature and acidity levels affect its carbonate chemistry, and calcifying organisms that depend on the calcium carbonate saturation state (ΩCaCO₃) to build their skeleton may be vulnerable to these changes. Despite their important roles in the marine environment, little is known about the vulnerability of calcareous sponges under these stressors. We performed an acute short-term experiment (9 days) with thermal and pH stresses to explore their effects on the skeleton and microbiome of the calcareous sponge Sycettusa hastifera. We observed that sponge spicules showed no corrosion and no Mg/Ca ratio variation when exposed to stress conditions. However, the outermost spicules were smaller in low pH treatment, although these effects were often diminished when higher temperatures were also applied. In general, the sponges synthesized normally shaped spicules under stress conditions, but the proportion of deformed spicules increased significantly in elevated temperature. In addition, we observed a stable host–microbiome association in which there is microbiome flexibility under thermal and pH stresses with a significantly increase in abundance of some associated bacteria. Our results suggest that S. hastifera has low vulnerability under the future ocean conditions here designed, since it showed indications of resistance that could help them adapt and survive.

中文翻译：

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评估钙质海绵在热和 pH 胁迫下的骨架和微生物组反应

海洋较高的温度和酸度水平会影响其碳酸盐化学，依赖碳酸钙饱和状态 (ΩCaCO ₃ ) 来构建骨骼的钙化生物可能容易受到这些变化的影响。尽管它们在海洋环境中发挥着重要作用，但人们对这些压力源下钙质海绵的脆弱性知之甚少。我们进行了一项急性短期实验（9 天），其中包括热应激和 pH 应激，以探索它们对钙质海绵Sycettusa hastifera的骨骼和微生物群的影响. 我们观察到海绵针状体在暴露于应力条件下时没有显示出腐蚀和 Mg/Ca 比变化。然而，最外面的针状体在低 pH 值处理中更小，尽管当也应用更高的温度时，这些影响通常会减弱。一般来说，海绵在应力条件下合成正常形状的针状体，但变形的针状体比例在升高的温度下显着增加。此外，我们观察到稳定的宿主-微生物组关联，其中在热和 pH 胁迫下微生物组具有灵活性，一些相关细菌的丰度显着增加。我们的结果表明S. hastifera 在此处设计的未来海洋条件下，它们的脆弱性较低，因为它显示出可以帮助它们适应和生存的抵抗迹象。