厚壳贻贝在海水酸化和微塑料复合作用下的生理应答

Since the industrial revolution, human activity has become an additional force in the global climate system, as exemplified by greenhouse gas emissions such as CO2 derived from the burning of fossil fuels, CO2 absorbed by ocean changes seawater chemistry, resulting in decreasing seawater pH. In recent years, microplastic pollution in the marine environment has become worldwide because a great deal of plastic ends up into ocean. The main inputs of plastics into the sea derive from beaches and land-based sources like rivers. The East China Sea (ECS) adjoining the region of the Yangtze Estuary which is most important industrial and economic center in China is vulnerable to plastic accumulation and excess CO2. So seawater acidification and microplastic pollution in this place is predicted to be much more frequent in future. This research aims to systematically explore the combined effects of ocean acidification and microplastic pollution on the physiological responses of the local representative economic bivalve, thick shell mussel Mytilus coruscus under laboratory conditions, from nutrition (digestive enzymes, ); bioenergetics (energy budget); histology (variation of microstructure of gill and digestive tract) and stress (oxidative stress in digestive tract) aspects. Dynamic changes of various physiological and biochemical indices in the mussels of different treatments will be studied, in order to evaluate the physiological response of the thick shell mussel to the two studied co-occurring stressors. This study will illuminate the physiological mechanism of pH and microplastic on mussels, and provide theoretical basis for evaluating the physiological effects of ocean acidification and microplastic pollution on mussels.

工业革命以来，人类活动排放二氧化碳气体逐年增多导致海水逐渐酸化；近些年塑料产品的大量使用并废弃于海洋导致海水微塑料逐年增多，我国东海紧邻长三角经济带，为长江入海口，受人类活动影响严重，海水酸化和微塑料污染尤为突出。本研究以中国东海典型经济贝类厚壳贻贝为研究对象，运用析因实验从营养学（消化酶、微塑料体内积聚、消化道菌群）、生物能量学（能量收支）、组织学（鳃和消化道的组织结构变化）和应激学（消化道氧化应激）角度，探究厚壳贻贝在海水酸化和微塑料复合作用下的生理应答；阐明海水酸化和微塑料对厚壳贻贝生理反应的交互影响；掌握厚壳贻贝在海水酸化和微塑料胁迫下生理生化指标变化规律；为气候变化及环境污染对海洋生态系统危害评估工作积累基础资料。

工业革命以来，人类社会对石化产品的开发使用逐年增加。石油天然气的使用过程释放大量的二氧化碳，导致全球变暖，海洋酸化；与此同时石油纯化过程中的副产品被人们制作成塑料，塑料产品使用报废后被遗弃形成亿万吨的塑料垃圾，这些塑料垃圾随着降雨河流逐步地汇聚到海洋，导致海洋塑料污染日益严重。海洋贝类尤其是近海贝类，直接面临海洋环境变化的挑战，基于此本项目展开了海洋酸化和微塑料暴露的复合影响对海洋贝类生理影响相关研究。通过研究发现海水酸化和微塑料暴露对海洋贝类幼体阶段具有显著影响。海水酸化和微塑料暴露，可以导致贝类幼体发育畸形率升高，发育时间延长，同时也会影响贝类幼体的游动行为，导致游动能力减弱；且海水酸化和微塑料暴露之间存在显著的交互作用。微塑料存在会加剧海水酸化对贝类幼体有发育的消极影响。对成年贻贝研究发现，海水酸化会导致贻贝消化相关酶以及生长净能积累的减少，但是微塑料暴露并没有显著影响贻贝消化相关酶活力亦未引起生长净能积累的减少。进一步的对贻贝肠道菌群微生物多样性进行分析发现，海水酸化和微塑料暴露并没有引起肠道菌群微生物组成发生改变。.贝类幼体发育阶段是贝类生命周期最脆弱时期，发育延迟以及游动能力减弱都会增加其在自然环境中的死亡率。海水酸化和微塑料暴露，虽然在成贝阶段没有显现显著的消极作用，但是在贝类幼体阶段有明显的消极影响。海洋贝类幼体顺利变态孵化对于贝类种群保持稳定举足轻重，而海水酸化和微塑料暴露在这一阶段对贝类有显著的消极作用这对贝类种群数量的维护必将产生影响。