Collaborative Proposal: Site Survey and Initial Characterization of North Pond: Microbiology, Biogeochemistry, Seismic Profiles

微生物细胞存在于世界海洋的浅层和深层沉积物中。这些细胞构成了地球原核生物量的主要部分，它们的活性催化了埋藏的有机物质的分解。同样，微生物在洋壳中定居，导致年轻的海脊侧翼玄武岩发生氧化蚀变。尽管它们在世界各地都很丰富，但这些生物的多样性、栖息地和传播途径却很难确定。关于它们的功能基因和代谢活动，使这些原核生物能够在年轻的地壳环境中生长和生存，我们知之甚少。北池是一个孤立的东北向沉积物池，位于大西洋中脊西侧，北纬22度45分，西经46度05分;它的周围和下面是年轻的（7 Ma）多孔洋中脊玄武岩，它与大西洋深海盆地和外脊侧翼的沉积物盖层隔离。这种设置提供了一个“自然实验室”，检查地下微生物群落的传播途径，发生和殖民模式。特别是研究可以区分细菌和古菌从深海水柱，深地下沉积物，和脊侧翼玄武岩。当前深层地下微生物学关注的问题是“那里有什么样的微生物生命，为什么？”“而避免了必要的补充“它是怎么到那里的？“这项研究将实现这一目标，并设想在北池塘建立一个微生物观测站，作为未来IODP活动的一部分。通过追踪北池沉积物中的物理和化学“特征”，研究将限制流体输送途径和流速，这些将与特定地点的微生物组成，关键代谢基因库和地下微生物群落的生物地球化学活动相关。本研究的重点是详细映射的沉积物-基底界面的北池，耦合热流，地震信息和孔隙流体化学数据的沉积物微生物采样。目标有两个方面：1）对北塘进行全面的现场调查，包括限制水文条件，为即将到来的IODP北塘巡航做准备，2）结合沉积物环境的生物地球化学特征和流动路径，对近地表微生物群落进行调查。这次实地考察航行将使船上和岸上的方法和样本处理得到必要的改进，为我们的海洋综合勘探方案航行做准备。更广泛的影响。海洋次表层生物群落的生物地球化学活动、组成及其时空动态是海洋科学和地球微生物学的一个新兴的中心课题。研究人员计划通过课程材料的整合以及REU学生的直接参与，将研究结果直接整合到他们机构正在进行的本科生和研究生教育中。研究人员将通过JOI杰出演讲者系列吸引更广泛的公众。最后，这次现场调查是一个更大的愿景的一部分，即将北池发展成为一个国际协调的地下微生物学基准研究（即，微生物观测站）。

Microbial cells occur in shallow and deep sediments throughout the world's oceans. These cells constitute a major portion of the Earth's prokaryotic biomass and their activity catalyzes the decomposition of buried organic matter. Similarly, microorganisms colonize the ocean crust, leading to the oxidative alteration of young ridge flank basalts. Despite their cosmopolitan abundance, the diversity, habitat, and dispersal pathways of these organisms are poorly defined. Little is known regarding their functional genes and the metabolic activities that allow these prokaryotes to grow and survive in the young crustal environment. North Pond is an isolated northeast-trending sediment pond on the western flank of the Mid-Atlantic Ridge (MAR) at 22deg45'N and 46deg05'W; it is surrounded and underlain by young (7 Ma), porous mid-ocean ridge basalt, and it is isolated from the sediment cover of the Atlantic abyssal basins and outer ridge flanks. This setting provides a "natural laboratory" for examining subsurface microbial community dispersal pathways, occurrence, and colonization patterns. In particular studies can differentiate bacteria and archaea from the deep-sea water column, deep subsurface sediments, and ridge flank basalt. Current deep subsurface microbiology focuses on the question "What kind of microbial life is there, and why?" while avoiding its necessary complement "How did it get there?" This study will accomplish that goal with a vision toward establishing a microbial observatory at North Pond as part of future IODP campaigns. By tracing physical and chemical "signatures" in North Pond sediments, the research will constrain fluid transport pathways and flow rates, and these will be correlated to site-specific microbial composition, key metabolic gene repertoire, and biogeochemical activity of subsurface microbial communities. This research focuses on detailed mapping of the sediment-basement interface of North Pond, by coupling heat flow, seismic information, and pore fluid chemistry data to microbial sampling of the sediments. The goals are two-fold: 1) to conduct a comprehensive site survey of North Pond that includes constraining the hydrology in preparation for our upcoming IODP cruise to North Pond, and 2) to perform a survey of near-surface microbial communities in conjunction with the biogeochemical characteristics and flow paths of their sediment environment. This site survey cruise will permit necessary refinement in shipboard and shore-based methodology and sample handling in preparation of our IODP cruise. Broader Impacts. The biogeochemical activities, composition and temporal and spatial dynamics of marine subsurface communities are an emerging central topic in marine sciences and geomicrobiology. The researchers plan to integrate the findings directly into ongoing undergraduate and graduate student education at their institutions through integration of materials in coursework, and the direct involvement of an REU student. The researchers will engage the broader public via the JOI distinguished Speaker series. Finally, this site survey is part of a much larger vision to develop North Pond into an internationally coordinated benchmark study in subsurface microbiology (i.e., a microbial observatory).