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

与甲烷渗漏有关的自生碳酸盐沉淀通常是由甲烷的厌氧氧化(AOM)介导的。这种微生物过程产生了大量的碳酸盐岩，给大陆边缘带来了栖息地的异质性，并为从海底释放的甲烷碳提供了一个主要的储存库。这项研究将通过描述演替背景下相关的微生物、有孔虫、大型动物和大型动物群落，调查这些碳酸盐底物在渗漏环境中形成独特生态系统的程度。碳酸盐岩的调查和取样将在哥斯达黎加边缘(730-1300米)和俄勒冈州边缘(590米)的水合物岭北部的4个半深海地点进行。位置差异和与之相关的水深、氧气、渗漏大型动物和碳酸盐地层变化预计将影响群落组成。这项研究将描述活跃、弱和无甲烷渗漏的碳酸盐岩组合，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-水界面活跃渗漏条件下，自生碳酸盐作为一个由AOM提供燃料的独特生态系统发挥作用，具有自己的(化学合成)初级和次生产物来源；(2)渗漏碳酸盐动物群经历甲烷供应和微生物活动驱动的演替；(3)固着渗漏碳酸盐组合主要包括微生物、原生动物和后生动物，它们在分类和演化上与周围渗漏沉积物的生物群不同，但在生态和演化上与深海、硬底质和还原动物群有关，包括来自渗漏、喷口、珊瑚丘和鲸骨的动物群。将对单一岩石进行裂解和切片，以进行碳酸盐矿物学和同位素分析、内生微生物及其各自的三角洲13C特征的FISH-SIMS分析、动物群(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肪分析，有孔虫测试和软体动物贝壳的三角洲18O和三角洲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用品。古生菌和AOM被认为是两者的关键。将在活跃和不活跃的地点部署去风化碳酸盐底物1年，以研究早期动物群落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，加上适当的操纵控制，将提供关于动物群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。将与渗漏沉积物、其他生物底物(贻贝、蛤、管虫)以及其他深海减少和硬地系统(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分类群将被作为系统发育分析的目标，以评估与来自其他硬地减少生态系统(喷口)的动物的进化亲缘关系。广泛影响：这项研究对社会的好处包括：(1)了解渗漏碳酸盐生态系统，以改善海洋资源管理，更全面地评估海底生物多样性、碳循环和对极端环境的适应；(2)碳酸盐生态系统演替变化的模型，并使用其动物群作为替代，更准确地评估过去的甲烷释放和古气候变化。教育和外展将包括当地学校介绍、网站开发和对本科、研究生和博士后水平的未来科学家的跨学科、实践和海上培训，包括通过SURF、STAR和REU计划招募的代表不足的群体(女性；来自农村社区的第一代大学生)。研究成果将被纳入深海生物学、微生物学、地质学、古生物学、海洋学和海底生态学课程的讲座、练习和实地考察，并纳入由海洋生物普查和硅底栖无脊椎动物收藏管理的网站和数据库。

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.