天然气水合物分解的甲烷对海洋生物的影响

随着海底环境的变化以及全球变暖的加剧，天然气水合物分解释放出大量甲烷到海洋中，其中一部分甲烷会穿过海水释放到大气中，导致大气中的温室气体增加，从而加剧了全球暖化。本文从甲烷的释放和运移路径角度梳理和总结了甲烷对海洋生物的直接和间接影响。首先，水合物分解释放甲烷，在海底形成冷泉渗漏区，滋养了一批特殊的生物群落，而甲烷是其形成生命元素中不可或缺的要素，由此繁衍形成了冷泉生态系统。其次，甲烷释放到海水中会引起海水酸化，海水酸化不仅会导致钙化生物合成碳酸钙外壳受阻，还会加速已生成外壳的溶解。最后，甲烷作为强温室气体释放到大气中还会加剧全球变暖；此外，极地冻土层的融化也会使得冻土区天然气水合物分解，导致大量甲烷进入大气中，从而致使海水暖化，海水的暖化又会对海洋生物的生存、代谢、繁殖、发育和免疫应答等多种生命活动造成影响。以上认识为进一步研究甲烷对未来海洋生态系统的影响提供重要参考信息。

Effect of Methane from Natural Gas Hydrate Decomposition on Marine Life

With changing seabed environment and the intensification of global warming, more natural gas hydrates have decomposed and released large amount of methane into the oceans. Some of the methane would ascend through the seawater and enter the atmosphere, which would increase the atmospheric greenhouse gas concentration, and thereby exacerbate global warming. From the perspective of methane release and migration pathways, the direct/indirect effects of methane on marine life are elucidated and summarized: (1) hydrates decompose to release methane, which is an indispensable compound in lifeform formation. This provides energy and material for autotrophic microorganisms, and supplies the food base of cold-spring biota. This maintains cold-spring biota based on a food chain of chemoautotrophic bacteria, which multiply in the cold-spring ecosystem; (2) some of the methane gas would diffuse and dissolve in the seawater, which causes seawater acidification. Seawater acidification would both affect the biosynthesis of calcium carbonate shells (calcification) and accelerate the shell dissolution; (3) as a strong greenhouse gas, the released methane in the atmosphere would exacerbate global warming. In addition, the melting of the polar permafrost would also release large amount of methane into the atmosphere, which generates an adverse cycle. The warming of seawater would affect the survival, metabolism, reproduction, development and immune response of marine life and other biological activities. Our findings provide important reference for future research on the impact of methane on marine ecosystem.