Program     PACECS: Processes and Approaches of Coastal Ecosystem Carbon Sequestration/ MEMCS: Mechanisms and Environmental Effects of Microbes on Carbon Sequestration       Poster Hydrosphere Microorganism Program: Regulating mechanisms and environmental effects of microbes on carbon sequestration and source in typical seas of China P-SPS2-01 Nianzhi Jiao* , State Key Laboratory of Marine Environmental Science, Xiamen University Presenter Email: Jiao@xmu.edu.cn This project is a part of NSFC Major Research Program "Hydrosphere Microorganism Program". The Hydrosphere Microbes program represents one of the major national efforts in understanding the roles of microbes in hydrosphere, particularly that related to geochemical cycling which ultimately impacts upon global ecology and environment/climate. The ocean is the largest hydrosphere and active carbon pool on Earth, which is equivalent to the total CO2 in the atmosphere. "Microbial carbon pump" (MCP) is major source and mechanism of marine carbon sink, significantly contributing to the organic carbon sink. The increasing eutrophication of coastal waters in China is often accompanied by environmental problems such as algal blooms, hypoxia and acidification, which may affect the carbon storage efficiency of MCP. The project will follow the overall guidance of the "Hydrosphere Microbiology Project", with the coastal eutrophication as the background, the MCP as the main theme, to investigate the effects and responses of algal blooms, hypoxia and acidification on major ecological processes and microbial communities. This project combines the field investigation, enclosures and laboratory research by using marine microbiology and chemistry to establish the linkages between the microorganism microcosmic process and the macrocosmic effect of the marine carbon cycle.