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

微生物细胞存在于世界各地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生物量的主要部分，它们的活动催化了埋藏的有机物的分解。类似地，微生物在洋壳中定居，导致年轻的山脊两侧玄武岩的氧化蚀变。尽管它们在世界各地都很丰富，但这些生物的多样性、栖息地和传播路径还没有明确的定义。人们对这些原核生物在年轻的地壳环境中生长和生存的功能基因和代谢活动知之甚少。北池是一个孤立的东北向沉积池塘，位于北纬22°45‘，西经46°05’的大西洋中脊(MAR)西侧；它被年轻的(7 Ma)多孔的大洋中脊玄武岩包围和衬托，与大西洋深海盆地和外脊两侧的沉积物盖层隔绝。这种环境为研究地下微生物群落的传播途径、发生和定植模式提供了一个“天然实验室”。特别是，研究可以区分深海水柱、深层地下沉积物和海脊两侧玄武岩中的细菌和古菌。当前深层地下微生物学关注的问题是“存在什么样的微生物生命，为什么？”同时避免使用必要的补语“它是怎么做到的？”这项研究将实现这一目标，愿景是在北池建立一个微生物观测站，作为未来IODP活动的一部分。通过追踪北塘沉积物中的物理和化学“特征”，这项研究将限制流体的运输路径和流速，这些将与特定地点的微生物组成、关键的代谢基因库和地下微生物群落的生物地球化学活动相关联。本研究重点是通过将热流、地震信息和孔隙流体化学数据与沉积物微生物采样相结合，详细绘制北塘沉积物-基底界面图。目标有两个：1)对北池进行一次全面的现场调查，其中包括限制水文，为我们即将到来的IODP北池邮轮做准备，以及2)结合其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。这次现场勘测巡航将允许对舰载和岸基方法以及样品处理进行必要的改进，以准备我们的IODP巡航。海洋次表层群落的生物地球化学活动、组成和时空动态是海洋科学和地球微生物学领域新兴的中心议题。研究人员计划通过将材料整合到课程作业中，并让一名REU学生直接参与，将这些发现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，目的是将北池发展成为地下微生物学的国际协调基准研究(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).