Collaborative Research: Structure, Function and Evolution of Authigenic, Methane-Derived Carbonate Ecosystems

合作研究：自生甲烷衍生碳酸盐生态系统的结构、功能和演化

• 批准号: 0825791
• 负责人: Victoria Orphan
• 金额: $ 32.1万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-10-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0825791&HistoricalAwards=false
• 关键词: Collaborative; Research; Structure; Function; Evolution

Authigenic carbonate precipitation associated with methane seepage is typically mediated by anaerobic oxidation of methane (AOM). This microbial process produces massive amounts of carbonate rock, introducing habitat heterogeneity to continental margins and providing a major repository for methane-derived carbon released from the sea floor. This study will investigate the extent to which these carbonate substrates form a distinct ecosystem within the seep environment by characterizing associated microbial, foraminiferal, macrofaunal and megafaunal communities in a successional context. Surveys and sampling of carbonate will take place at 4 bathyal locations on the Costa Rica margin (730-1300 m) and at Hydrate Ridge North on the Oregon margin (590 m). Location differences and associated water depth, oxygenation, seep megafauna and carbonate formation variation are expected to influence community composition. This study will characterize assemblages inhabiting carbonates subject to active, weak and no methane seepage, and conduct rock colonization and transplant experiments to address the following main hypotheses:(1) Under conditions of active seepage at the seafloor-water interface, authigenic carbonate functions as a distinct ecosystem fueled by AOM, with its own sources of (chemosynthetic) primary and secondary production; (2) Seep carbonate faunal communities undergo succession driven by methane supply and microbial activity; (3) Sessile seep carbonate assemblages include mainly microbial, protozoan and metazoan species that are taxonomically and evolutionarily distinct from the biota of surrounding seep sediments, but ecologically and evolutionarily related to deep-sea, hard-substrate and reducing faunas, including those from seeps, vents, coral mounds and whale bones. Single rocks will be split and sectioned for carbonate mineralogy and isotopic analysis, FISH-SIMS analyses of endogeneous microorganisms and their respective delta 13C signatures, faunal (protozoan and metazoan) taxonomic, lifestyle and position studies. Stable isotopic and lipid analyses of foraminifera and metazoan protoplasm, delta 18O and delta 13C signatures of foraminiferan tests and mollusk shells will be linked to microbial and carbonate signatures to assess trophic pathways and paleo proxies for methane release. Archaea and AOM are hypothesized as key to both. Defaunated carbonate substrates will be deployed at active and inactive sites for 1 year to examine early faunal succession and the role of external seepage. Rocks transplanted between inactive and active sites, with appropriate manipulation controls, will provide additional information about faunal reliance on seepage and persistence of AOM in the absence of seepage. Community comparisons will be drawn with seep sediments, other biotic substrates (mussels, clams, tubeworms) and with other deep-sea reducing and hardground systems (vents, whales, deep-water corals). Macrofaunal assemblages will be DNA and selected annelid and foraminiferan taxa will be targeted for phylogenetic analyses to assess evolutionary affinities with fauna from other hardground-reducing ecosystems (vents).Broader Impacts: Benefits of this research to society include: (1) an understanding of seep carbonate ecosystems for improved marine resource management and more comprehensive assessments of seafloor biodiversity, carbon cycling, and adaptations to extreme environments; and (2) a model for successional changes in carbonate ecosystems and the use of their faunas as proxies to more accurately assess past methane release and paleoclimate change. Education and outreach will include local school presentations; web site development and interdisciplinary, hands-on, at-sea training of future scientists at undergraduate, graduate, and post-doc levels, including under-represented groups (women; first-generation university students from rural communities) recruited through SURF, STARS and REU programs. Research results will be incorporated into lectures, exercises and field trips for deep-sea biology, microbiology, geology, paleontology, oceanography and benthic ecology courses, and onto websites and databases managed by the Census of Marine Life and the SIO Benthic Invertebrate Collection.

与甲烷渗漏相关的自生碳酸盐沉淀通常是由甲烷厌氧氧化（AOM）介导的。这种微生物过程产生大量碳酸盐岩，将栖息地异质性引入大陆边缘，并为海底释放的甲烷衍生碳提供了主要储存库。本研究将通过表征连续背景下相关的微生物、有孔虫、大型动物和巨型动物群落，研究这些碳酸盐基质在渗流环境中形成独特生态系统的程度。碳酸盐调查和采样将在哥斯达黎加边缘 (730-1300 m) 的 4 个深海位置和俄勒冈州边缘的水合物岭北 (590 m) 进行。位置差异和相关水深、氧合、渗流巨型动物和碳酸盐形成变化预计会影响群落组成。本研究将表征受活跃、弱和无甲烷渗流影响的碳酸盐岩组合，并进行岩石定植和移植实验，以解决以下主要假设：（1）在海底-水界面活跃渗流条件下，自生碳酸盐的功能为由 AOM 推动的独特生态系统，拥有自己的（化学合成）初级和次级生产来源； （2）渗流碳酸盐动物群落在甲烷供应和微生物活动的驱动下经历演替； (3) 固着渗流碳酸盐组合主要包括微生物、原生动物和后生动物物种，这些物种在分类学和进化上与周围渗流沉积物的生物群不同，但在生态和进化上与深海、硬基质和还原动物群相关，包括来自渗流的动物群、喷口、珊瑚丘和鲸骨。单块岩石将被分割和切片，用于碳酸盐矿物学和同位素分析、内生微生物及其各自的 Delta 13C 特征的 FISH-SIMS 分析、动物（原生动物和后生动物）分类、生活方式和位置研究。有孔虫和后生动物原生质的稳定同位素和脂质分析、有孔虫测试和软体动物壳的 Delta 18O 和 Delta 13C 特征将与微生物和碳酸盐特征联系起来，以评估甲烷释放的营养途径和古代理。古生菌和 AOM 被认为是两者的关键。动物区系丧失的碳酸盐基质将在活跃和非活跃地点部署一年，以检查早期动物群演替和外部渗漏的作用。在不活跃和活跃地点之间移植的岩石，通过适当的操作控制，将提供有关动物对渗漏的依赖以及在没有渗漏的情况下 AOM 持续存在的额外信息。将与渗流沉积物、其他生物基质（贻贝、蛤、管虫）以及其他深海还原和硬地系统（喷口、鲸鱼、深水珊瑚）进行群落比较。大型动物组合将是 DNA，选定的环节动物和有孔虫类群将成为系统发育分析的目标，以评估与其他硬质减少生态系统（喷口）的动物群的进化亲缘关系。 更广泛的影响：这项研究对社会的好处包括：（1）了解渗透碳酸盐生态系统，以改善海洋资源管理并对海底生物多样性、碳循环和极端环境适应进行更全面的评估； (2) 碳酸盐生态系统的连续变化模型，并使用其动物群作为替代指标，以更准确地评估过去的甲烷释放和古气候变化。教育和推广将包括当地学校的演示；网站开发以及对本科生、研究生和博士后级别的未来科学家进行跨学科、实践性、海上培训，包括通过 SURF、STARS 招募的代表性不足的群体（女性；来自农村社区的第一代大学生）和 REU 计划。研究成果将纳入深海生物学、微生物学、地质学、古生物学、海洋学和底栖生态学课程的讲座、练习和实地考察，以及由海洋生物普查和 SIO 底栖无脊椎动物收藏管理的网站和数据库。