Although seagrasses are expected to thrive in future acidified oceans by overcoming low CO2 diffusion into plant tissues, the co‐occurrence of environmental stressors may affect their growth. Volcanic CO2 vents are often associated with toxic gases and metal‐rich fluids representing ideal sites to assess the effects of multiple stressors. We evaluated the response of Posidonia oceanica growing near shallow CO2 vents characterized by H2S spill‐out by comparing meadow structure and phenology to an area with no gas emissions. Seagrass descriptors at meadow, shoot and leaf level indicated that P. oceanica experienced stressful conditions at the vent area, in clear contrast to the flourishing features of P. oceanica previously described at CO2 vents with no evidence of toxic inputs. Furthermore, the reduction in both leaf δ34S and growth at the vent area indicates that sulfide intrusion occurs and affects seagrass growth performance, dampening the expected beneficial effects of high CO2 levels.

中文翻译：

---

联合暴露于 CO2 和 H2S 会显着降低地中海海草 Posidonia oceanica 的性能：来自火山口的证据


尽管海草有望通过克服二氧化碳扩散到植物组织中的问题而在未来的酸化海洋中茁壮成长，但环境压力因素的同时出现可能会影响它们的生长。火山二氧化碳喷口通常与有毒气体和富含金属的液体有关，是评估多种压力源影响的理想场所。我们通过比较草甸结构和物候与无气体排放的区域，评估了生长在以硫化氢溢出为特征的浅层二氧化碳喷口附近的 Posidonia oceanica 的响应。草甸、枝条和叶子水平的海草描述符表明，P. oceanica 在喷口区域经历了应激条件，这与之前描述的没有有毒输入证据的 CO2 喷口处 P. oceanica 的繁茂特征形成鲜明对比。此外，叶子 δ34S 和喷口区域生长的减少表明发生了硫化物入侵并影响海草生长性能，从而削弱了高二氧化碳水平的预期有益效果。