Collaborative Research: Redefining the footprint of deep ocean methane seepage for benthic ecosystems

合作研究：重新定义深海甲烷渗漏对底栖生态系统的足迹

• 批准号: 2048481
• 负责人: Shana Goffredi
• 金额: $ 12.88万
• 依托单位: Occidental College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-10-01 至 2024-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2048481&HistoricalAwards=false
• 关键词: Collaborative; Research; Redefining; footprint; deep

This research examines the role of deep-sea organisms in determining the fate and footprint of methane, a potent greenhouse gas, on Pacific continental margins. The investigators are evaluating the deep ocean methanosphere defined by the microbial communities that consume methane and the animals that directly feed on or form symbioses with methane-consuming microbes. They are also investigating animal communities that gain energy indirectly from methane, as well as those that take advantage of carbonate rocks, the physical manifestation of methane consumption in seafloor sediments. The study of methane seeps in the deep waters of both Alaska (4400-5500 meters) and Southern California (450-1040 meters) is enabling comparisons of the methanosphere under different food-limitation and oxygen regimes. By applying diverse chemical, isotopic, microscopy, and genetic-based analyses to seep microbes and fauna, this study is advancing understanding of the contribution of methane to deep-sea biodiversity and ecosystem function, information that can inform management and conservation actions in US waters. In addition to training for graduate and undergraduate students at their home institutions, the investigators are collaborating with the Alaska Native Science and Engineering Program (ANSEP). They are recruiting Alaskan undergraduates to participate in the research, contributing to ANSEP’s online resources that promote interaction between scientists and middle and high school students, and participating in ANSEP’s annual residential Career Exploration in Marine Science programs to engage middle school students in learning about deep-sea ecosystems and the variety of career pathways available in marine related fields. Microbial production and consumption of methane is dynamic and widespread along continental margins, and some animals within deep-sea methane seeps rely on the oxidation and sequestration of methane for nutrition. At the same time, understanding of methane-dependent processes and symbioses in the deep-sea environment is still rudimentary. The goals of this study are to 1) examine the diversity of animals involved in methane-based symbioses and heterotrophic consumption of methane-oxidizing microbes and how these symbioses extend the periphery of seeps, contributing to non-seep, continental slope food webs; and 2) determine whether carbonates on the seep periphery sustain active methanotrophic microbial assemblages, providing a localized food source or chemical fuel for thiotrophic symbioses, via anaerobic oxidation of methane, or free-living, sulfide-oxidizing bacteria consumed by animals. The investigators are addressing these goals by surveying, sampling, and characterizing microbes, water, sediments, carbonates and animals at a deep seep site on the Aleutian Margin and a shallow site off Southern California. Shipboard experiments and laboratory analyses are using molecular, isotopic, geochemical, and radiotracer tools to understand transfer of methane-sourced carbon from aerobic methanotrophs under multiple oxygen levels, pressures, and photosynthetic food inputs. This approach offers a wide lens by which to examine the methane seep footprint, allow reinterpretation of past observations, and identify new scientific areas for future study. Improved characterization of the deep continental margin methanosphere informs climate science, biodiversity conservation, and resource management.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这项研究探讨了深海生物在决定太平洋大陆边缘甲烷（一种强效温室气体）的命运和足迹方面的作用。研究人员正在评估由消耗甲烷的微生物群落以及直接以消耗甲烷的微生物为食或与消耗甲烷的微生物形成共生的动物所定义的深海甲烷圈。他们还在调查从甲烷间接获取能量的动物群落，以及利用碳酸盐岩（海底沉积物中甲烷消耗的物理表现）的动物群落。对阿拉斯加（4400-5500 米）和南加州（450-1040 米）深水中甲烷渗漏的研究使得能够比较不同食物限制和氧气条件下的甲烷层。通过对渗流微生物和动物群应用多种化学、同位素、显微镜和基于遗传的分析，这项研究正在加深对甲烷对深海生物多样性和生态系统功能的贡献的理解，这些信息可以为美国水域的管理和保护行动提供信息。除了在本国机构为研究生和本科生提供培训外，研究人员还与阿拉斯加本土科学与工程计划 (ANSEP) 合作。他们正在招募阿拉斯加本科生参与这项研究，为 ANSEP 的在线资源做出贡献，以促进科学家与中学生之间的互动，并参加 ANSEP 的年度海洋科学住宿职业探索项目，让中学生了解深海生态系统以及海洋相关领域的各种职业道路。 甲烷的微生物生产和消耗在大陆边缘是动态且广泛的，深海甲烷渗漏中的一些动物依赖甲烷的氧化和封存来获取营养。与此同时，对深海环境中依赖甲烷的过程和共生关系的了解仍然处于初级阶段。这项研究的目标是 1) 检查参与基于甲烷的共生和甲烷氧化微生物的异养消耗的动物的多样性，以及这些共生如何延伸渗漏的外围，从而形成非渗漏的大陆坡食物网； 2）确定渗漏周边的碳酸盐是否维持活跃的甲烷氧化微生物群落，通过甲烷的厌氧氧化或动物消耗的自由生活的硫化物氧化细菌，为硫营养共生体提供局部食物来源或化学燃料。研究人员正在通过在阿留申边缘的深渗点和南加州附近的浅滩对微生物、水、沉积物、碳酸盐和动物进行调查、采样和表征来实现这些目标。船上实验和实验室分析正在使用分子、同位素、地球化学和放射性示踪剂工具来了解在多种氧气水平、压力和光合食物输入下来自好氧甲烷氧化菌的甲烷源碳的转移。这种方法提供了一个广阔的视角来检查甲烷渗漏足迹，允许重新解释过去的观察结果，并确定未来研究的新科学领域。改进对深层大陆边缘甲烷层的表征，为气候科学、生物多样性保护和资源管理提供信息。该奖项反映了 NSF 的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。