Collaborative Research: A multidimensional approach to understanding microbial carbon cycling beneath the seafloor during cool hydrothermal circulation

合作研究：了解海底冷热液循环期间微生物碳循环的多维方法

• 批准号: 1635208
• 负责人: Julie Huber
• 金额: $ 49.97万
• 依托单位: Marine Biological Laboratory
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1635208&HistoricalAwards=false
• 关键词: Collaborative; Research; multidimensional; approach; understanding

The global ocean comprises Earth's largest microbiome, with at least half of the ocean's microbial biomass occurring beneath the ocean floor. In particular, oceanic crust encompasses the largest aquifer on Earth, with a liquid volume equal to approximately 2% of the ocean's volume. It also harbors a substantial reservoir of microbial life that may influence global-scale biogeochemical cycles. This project investigates this largest actively flowing aquifer system on Earth- the fluids circulating through oceanic crust underlying the oceans and sediments. Despite advancing knowledge about life in the deep ocean, the understanding of microorganisms in the rocky oceanic crust and the fluids flowing through it remains rudimentary. This project is focused on understanding the linkages between microbial activity and the cycling of carbon in the cool, subseafloor biosphere. The balance between organic carbon-consuming and organic carbon-producing metabolisms within the crustal biosphere will be determined using seafloor observatories put in place by the International Ocean Discovery Program (IODP) on the flanks of the Mid-Atlantic Ridge, likely representative of the majority of global hydrothermal fluid circulation. The rates of microbial transformations of carbon will be determined using both geochemical and biological approaches. Results will help establish the extent to which microbially-mediated processes in the subseafloor influence carbon cycling in the ocean. This work will represent the first comprehensive description of carbon cycling in the cold oxic crustal aquifer. Two female postdocs will be supported on the grant, and both high school and community college students will also be involved through collaborations with Cape Cod Community College and Cambridge-Rindge and Latin School. The goal is to promote science, technology, engineering and math literacy among high-school and community college students through hand-on research experiences, peer-to-peer mentoring, and professional development opportunities. The goal of the project is to answer the question "is the cool crustal subseafloor biosphere net autotrophic or net heterotrophic?" The focus of the effort is at North Pond, an isolated sediment pond located on ridge flank oceanic crust 7-8 million years old on the western side of the Mid-Atlantic Ridge. The two objectives of the project are to:1. Characterize suspended particles in subseafloor fluids with respect to their inorganic and organic carbon content, and natural 14C and 13C isotopic ratios, to determine microbially-mediated fluxes and processes.2. Characterize the net influence of particle-associated and free-living microbial communities on subseafloor fluid primary production and remineralization, as well as the taxon-specific contributions to these same processes.The integration of isotope geochemical and molecular biological approaches represents a significant cross-disciplinary advance in the understanding of the microbial ecology and geochemistry of the subseafloor biosphere in young oceanic crust and their role in maintaining global deep-sea redox balance. Expected outcomes include identifying signatures of autotrophic and heterotrophic metabolism in particle-associated and free-living subseafloor microbial communities as well as quantification of autotrophic and heterotrophic metabolism and associated taxon-abundances to provide insights into the net and specific microbial processes in crustal fluids on carbon fluxes.

全球海洋包含地球上最大的微生物群，海洋微生物生物量的至少一半存在于海底之下。特别是，洋壳包含地球上最大的含水层，其液体体积约等于海洋体积的 2%。它还蕴藏着大量的微生物生命库，可能影响全球范围的生物地球化学循环。该项目研究了地球上最大的活跃流动的含水层系统——通过海洋和沉积物下方的洋壳循环的流体。尽管人们对深海生命的认识不断进步，但对岩石洋壳中的微生物和流经其中的流体的了解仍然处于初级阶段。该项目的重点是了解凉爽的海底生物圈中微生物活动与碳循环之间的联系。地壳生物圈内有机碳消耗和有机碳产生代谢之间的平衡将通过国际海洋发现计划（IODP）在大西洋中脊两侧建立的海底观测站来确定，大西洋中脊可能代表了全球大部分热液循环。碳的微生物转化率将使用地球化学和生物学方法来确定。结果将有助于确定海底微生物介导的过程对海洋碳循环的影响程度。这项工作将首次全面描述冷含氧地壳含水层中的碳循环。两名女性博士后将获得这笔赠款的支持，高中和社区学院的学生也将通过与科德角社区学院和剑桥林奇和拉丁学校的合作参与其中。目标是通过实践研究经验、同行指导和专业发展机会，提高高中生和社区学院学生的科学、技术、工程和数学素养。该项目的目标是回答“冷地壳海底生物圈是净自养还是净异养？”的问题。这项工作的重点是北池，这是一个孤立的沉积物池，位于大西洋中脊西侧洋壳的山脊侧翼，已有 7 至 800 万年的历史。该项目的两个目标是： 1．表征海底流体中悬浮颗粒的无机和有机碳含量以及天然 14C 和 13C 同位素比率，以确定微生物介导的通量和过程。2．表征颗粒相关和自由生活的微生物群落对海底流体初级生产和再矿化的净影响，以及对这些相同过程的分类单元特异性贡献。同位素地球化学和分子生物学方法的整合代表了在理解年轻洋壳海底生物圈的微生物生态和地球化学及其在维持全球海洋中的作用方面的重大跨学科进展。 深海氧化还原平衡。预期结果包括识别颗粒相关和自由生活的海底微生物群落中自养和异养代谢的特征，以及对自养和异养代谢以及相关分类群丰度的量化，以深入了解地壳流体中碳通量的净和特定微生物过程。