海洋酸化对异养浮游细菌多样性及群落结构、功能的影响研究

Heterotrophic bacterioplankton play a major role in marine ecological system,so there is an urgent need to understand the ecological effect of ocean acidification on heterotrophic bacterioplankton because the pH of the oceans is now decreasing faster than any time before. Samples will be collected from East China Sea coastal area which is a typical marine habitats in this project, and the methods combination pyrosequencing and fuctional gene array technology will be used in order to focus on the following three aspects of the research:(1)the effect of ocean acidification on the diversity and community structure of heterotrophic bacterioplankton;(2)the effect of ocean acidification on hydrolytic enzyme activities and functional group of heterotrophic bacterioplankton;(3)meta-analysis to the effect of ocean acidification on the heterotrophic bacterioplankton in different coastal ecosystem. In this project, a series of objectives are planned to be achieved: the correlation between the diversity and community structure of marine heterotrophic bacterial and pH value of sea water could be determined, the law of change in the bacterial diversity and community structure on the presure of high CO2 and low pH could be finded,and the mechanism of the function population of heterotrophic bacterioplankton in response to ocean acidification could be discovered. The effect of ocean acidification on the function in biogeochemical process of heterotrophic bacterioplankton could be understanded through analyzing for changes of extracellular hydrolytic enzyme activities and microarray data.Through the data collection and statistical analysis, the ecology effect of ocean acidification on heterotrophic bacterioplankton of the coastal ecosystems could be summarized, with the purpose of providing scientific basis for the government to formulate relevant policies.

异养浮游细菌在海洋生态系统中发挥着重要作用，鉴于目前海洋酸化趋势日益严重，迫切需要了解海洋酸化对异养浮游细菌的生态效应。本项目选取东海近岸海域这一典型海洋生境，利用高通量测序与功能基因芯片技术相结合的方法，重点开展以下三个方面的研究：（1）海洋酸化对异养浮游细菌多样性和群落结构的影响；（2）海洋酸化对异养细菌胞外酶活性和功能种群的的影响；（3）不同沿岸生态系统酸化效应的Meta分析。通过项目研究，将确定东海近岸生态系统中海洋异养细菌多样性和群落结构与海水pH值之间的相关性，以及酸化环境下，细菌多样性和群落结构的变迁规律；初步探明海洋酸化环境下异养浮游细菌功能种群的响应机制，结合细菌胞外水解酶活性的变化，得出海洋酸化对异养细菌在生物地球化学进程中功能发挥的影响；通过数据收集和统计分析，总结海洋酸化对近岸生态系统异养浮游细菌的生态效应，为政府制订相关政策提供科学依据。

异养浮游细菌在海洋生态系统中发挥着重要作用，鉴于目前海洋酸化现象的日益严重，迫切需要了解海洋酸化对异养浮游细菌的生态效应。课题组选取东海近岸海域这一典型海洋生境，对该海域十年的历史监测数据进行了分析，结果显示海水pH变化趋势存在明显的季节和区域差异，共有10个站点表层海水pH呈下降趋势，主要集中于长江口和杭州湾海域。环境因子相关性分析显示，杭州湾海域夏季表层海水的pH值与叶绿素a浓度呈极显著正相关，其它海域两者间未显示出显著的相关性；杭州湾海域的pH值与海表温度也存在显著的相关性，但季节不同趋势不同，呈现出春季正相关而夏季负相关的特征；pH与盐度的关系在各海域表现得更加明显，长江口、杭州湾和三门湾三个调查海区海水的pH变化与盐度都存在显著的正相关。.利用传统克隆文库构建技术、高通量测序技术与功能基因芯片技术相结合的方法，对东海海域表层海水的异养细菌群落结构及与环境的相关性进行研究，结果显示细菌丰度与溶解氧（DO）、总碱度（TA）、化学需氧量（COD）、总悬浮颗粒物（TSP）等环境指标没有相关性，但pH与细菌丰度有显著相关性，PO43-浓度与细菌丰度则是极显著相关；细菌多样性主要包括变形菌门、拟杆菌门、放线菌门、蓝细菌门、厚壁菌门、绿弯菌门、酸杆菌门、浮霉菌门、纤维杆菌门、疣微菌门和柔膜菌门，以及SAR等，其中变形菌门是典型优势菌群；细菌的多样性及群落结构与酸化有显著相关性，Alpha-变形菌门与磷酸盐浓度正相关，Gramm-变形菌和柔膜菌门与pH浓度正相关，拟杆菌门与总悬浮颗粒物（TSP）浓度正相关；用picrust预测细菌群落结构的功能时发现，氧化磷酸化、固碳作用、甲烷代谢、氮代谢等功能在所有样品中都比较丰富。模拟酸化条件下（pH=7.6），海水群落多样性要比正常海水环境（pH=8.0）更高，相关性分析表明α-变形菌、疣微菌的丰度随着pH的降低明显降低，γ-变形菌和拟杆菌比例反之则显著上升。