海湾浮游细菌群落多样性和稳定性对增温的响应机制

Warming is seriously threatening the biodiversity and stability of the bay ecosystems. Bacterioplankton play a key role in the matter cycling and energy flow of the bay ecosystems. However, due to the limitations of research methods, the current studies about the impacts of warming on bacterioplankton communities in the bay ecosystems are very rare. This project is planned to be performed in the area strongly affected by the warm water drainage from the Nuclear Power Plant in the Daya Bay, which is heavily influenced by human activities. Both of the field investigations in situ and the indoor simulation experiments will be used in this project. We also plan to perform highthroughput sequencing, environmental metagenome, functional gene chip and the data bioinformatics analyses, 1) to study the effects and regulatory mechanisms of warming on bacterioplankton α and β diversity in the bay ecosystem, which is strongly impacted by human activities, 2) to clarify the regulatory roles of warming on bacterioplankton community structure and functional stability and their associations, 3) and to sort the key bacterial taxonomic groups and the specific functional groups in the disturbance and response processes. A null model of bacterioplankton community structure is constructed to elucidate the potential ecological or evolutionary mechanism underlying the succession of bacterioplankton communities in the disturbance and response processes, and also to reveal the regulatory mechanism of stochastic or deterministic processes on bacterial community resistance and resilience. The results of this project will not noly help to deeply understand the influences of climate warming on the structure, the ecological functions and the stability of the bay ecosystems, but also provide scientific evidences to improve the bay ecological environments and maintain the sustainable developments of the bay ecosystems.

气候变暖正严重威胁着海湾生物多样性和生态系统稳定性。浮游细菌在海湾生态系统物质循环和能量流动过程中起重要作用，但因研究手段限制，有关升温影响海湾浮游细菌群落的研究十分匮乏。本项目拟在受人类活动强烈影响的大亚湾核电站温排水区开展，通过野外观测与室内模拟实验相结合，运用高通量测序、环境宏基因组、功能基因芯片和大数据生物信息学分析等方法，研究在人类活动强烈影响的海湾生态系统中，升温对浮游细菌α和β多样性的影响及调控机制；阐明细菌群落结构和功能稳定性及其关联关系受升温的调节作用；甄选出环境干扰-响应过程中关键细菌类群/功能群；构建细菌群落零模型，阐明浮游细菌群落演替格局背后的潜在生态/进化机制，揭示随机性/决定性过程对细菌群落抵抗力和恢复力的调控机制。本项目有助于深入认识气候变暖影响下海湾生态系统的结构、生态功能及其稳定性，为改善海湾生态环境、维护海湾生态系统可持续发展提供科学依据。

气候变暖正严重威胁着水生生物多样性和生态系统稳定性。本项目通过野外观测与室内模拟实验相结合，运用高通量测序、环境宏基因组、功能基因芯片和大数据生物信息学分析等方法，研究结果表明在人类活动强烈影响的水生生态系统中，升温对水体细菌alpha多样性的影响不显著，但却显著促进了beta多样性的增加，细菌群落组成从以聚球藻为主的自养转变为以交替单胞菌、弧菌和假交替单胞菌为主的异养。当我们将水体细菌群落结构和功能关联起来分析发现，聚球藻在基因组水平上缺失抵御热胁迫相关功能的基因。然而，交替单胞菌、弧菌和假交替单胞菌的基因组包含了大量的DNA 修复系统、热休克反应分子伴侣和蛋白质的基因，以及参与生物膜形成和不饱和脂肪酸和聚糖的生物合成的基因。表明相比于自养聚球藻群落，异养微生物群落（交替单胞菌、弧菌和假交替单胞菌优势类群）能更好的适应海水热胁迫。此外，长期水体升温显着降低了水体细菌在光合作用、有机碳合成和能量产生过程中的代谢潜力，却显著增加了参与有机化合物降解和异化硝酸盐还原的基因，以在升温海水条件下获得物质和能量的补偿作用。本项目同时发现水体长期升温显著影响了水体细菌群落的稳定性，发现了在升温条件下，微生物群落微生物β多样性的增加不能支撑更高的群落稳定性。相反，在该条件下微生物群落对环境干扰（腐殖酸添加）的抵抗力显著降低，群落稳定性下降。进一步对水生微生物群落稳定性及其受水体升温影响的研究，发现了相比于冬季，南亚热带水生夏季微生物群落对升温更为敏感且更加难以预测。同时，微生物群落的环境过滤作用减弱和生态位分化增强是导致其群落稳定性下降的重要机制。本项目共发表学术论文7篇，其中 SCI 论文 6 篇。获得国家自然科学基金面上项目1项，协助培养硕士和博士生2名。本项目的研究结果将有助于深入了解水生生态系统对全球变暖的响应机制，且为丰富水域生态学的理论体系提供一定的基础数据和理论依据。

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