Collaborative Research: EAGER: Particle-specific DNA sequencing to directly observe ecological mechanisms of the biological pump

合作研究：EAGER：颗粒特异性 DNA 测序，直接观察生物泵的生态机制

• 批准号: 1703664
• 负责人: Colleen Durkin
• 金额: $ 16.24万
• 依托单位: San Jose State University Foundation
• 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: 2016-12-15 至 2019-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1703664&HistoricalAwards=false
• 关键词: Collaborative; Research; EAGER; Particle; specific

Carbon is fixed into organic matter by phytoplankton growing in the surface ocean, and is naturally sequestered in the ocean interior when particles and organisms sink: a process called the "biological pump." Because of its recognized influence on the global carbon cycle, ocean scientists have studied the biological pump for decades. However, we still do not have a sufficient understanding of the underlying processes to accurately quantify and predict carbon cycling. Much of this uncertainty stems from an inability to directly link specific plankton in the surface ocean with the types of particles sinking out of the surface ocean. To address this missing link in biological pump research, this work will directly observe how plankton are transported out of the surface ocean using novel, particle-specific observational approaches embedded within an interdisciplinary field program that will finely resolve upper ocean plankton groups and the resulting amount of sinking carbon across space and in time. The genetic identity of organisms within different types of sinking particles will be determined by sequencing the genetic contents of individually collected particles. This new application of a molecular method will definitively link surface plankton with sinking particles at five locations across the Pacific Ocean. This work has the potential to transform our understanding of the biological pump by identifying previously unknown links between surface ecosystems and sinking carbon particles. Because this work is embedded within an interdisciplinary field program, including biogeochemical modelers and remote sensing scientists, these data will feed directly into new models of the biological pump, improving our ability to quantify and predict carbon uptake by the ocean. This project will train 1 graduate student and at least 2 undergraduate researchers. Findings will be communicated to the non-scientific public through blogs, videos, and the public communication channels of participating institutions.Accurate prediction of the global carbon cycle requires an understanding of the specific processes that link surface plankton communities and sinking particulate carbon flux (export) out of the surface ocean, but current methodological paradigms in biological pump research do not directly observe these processes. This project will comprehensively determine who is exported from the surface ocean and how using new, particle-resolving optical and molecular techniques embedded within a sampling scheme that characterizes export events at high time and space resolution. The investigation suggests that different plankton types in the surface waters are transported out of the surface ocean by distinct export pathways, and that an understanding of these connections is critical knowledge for global carbon cycle modeling. If successful, this work has the potential to transform our conceptual understanding of the biological pump by directly identifying mechanisms that link surface plankton with particle export, without relying on bulk sampling schemes and large-scale correlation analysis. Particle export environments will be studied at five open ocean locations during a cruise from Hawaii to Seattle in January-February 2017. The surface plankton communities will be characterized by a combination of satellite observations, sensors attached to a free-drifting, continuously profiling WireWalker, an in situ holographic camera, microscopy, and by sequencing 18S and 16S rRNA gene fragments. Exported particles will simultaneously be captured by various specialized sediment traps and their characteristics will be directly related to their sources in the surface community by identifying the genetic contents of individual particle types. Individual particles will be isolated from gel layers and the 16S and 18S rRNA gene fragments will be amplified and sequenced. This work would, for the first time, combine molecular approaches with particle-specific observations to enable simultaneous identification of both which organisms are exported and the processes responsible for their export.

碳被生长在海洋表面的浮游植物固定到有机物质中，当颗粒和生物下沉时，碳自然被封存在海洋内部：这个过程称为“生物泵”。“由于它对全球碳循环的公认影响，海洋科学家已经研究了几十年的生物泵。然而，我们仍然没有足够的了解的基本过程，以准确地量化和预测碳循环。这种不确定性的大部分原因是无法直接将表层海洋中的特定浮游生物与沉出表层海洋的颗粒类型联系起来。为了解决生物泵研究中的这一缺失环节，这项工作将直接观察浮游生物如何使用嵌入在跨学科领域计划中的新颖的，特定于粒子的观测方法从海洋表面运输出来，该计划将精细地解决上层海洋浮游生物群以及由此产生的下沉碳量。不同类型沉降颗粒内生物的遗传特性将通过对单个收集颗粒的遗传内容进行测序来确定。这种分子方法的新应用将明确地将太平洋五个地点的表层浮游生物与下沉颗粒联系起来。这项工作有可能通过确定地表生态系统和下沉碳颗粒之间以前未知的联系来改变我们对生物泵的理解。由于这项工作是嵌入在一个跨学科的领域计划，包括地球化学建模和遥感科学家，这些数据将直接输入到生物泵的新模型，提高我们量化和预测海洋碳吸收的能力。本项目将培养1名研究生和至少2名本科生研究人员。研究结果将通过博客、视频和参与机构的公共交流渠道传达给非科学公众。准确预测全球碳循环需要了解连接表层浮游生物群落和海洋表层沉降颗粒碳通量（输出）的具体过程，但目前生物泵研究的方法范式并不直接观察这些过程。该项目将全面确定谁是从表层海洋输出的，以及如何使用嵌入采样方案中的新的粒子分辨光学和分子技术，以高时间和空间分辨率表征输出事件。调查表明，不同类型的浮游生物在表面沃茨被运出的表面海洋不同的出口途径，这些连接的理解是全球碳循环建模的关键知识。如果成功，这项工作有可能改变我们的概念理解的生物泵直接识别机制，表面浮游生物与颗粒出口，而不依赖于批量采样计划和大规模的相关性分析。2017年1月至2月，在从夏威夷到西雅图的巡航期间，将在五个开阔的海洋位置研究粒子输出环境。表层浮游生物群落的特征将通过卫星观测，传感器连接到一个自由漂移，连续剖析WireWalker，原位全息照相机，显微镜，并通过测序18S和16S rRNA基因片段的组合。输出的颗粒将同时被各种专门的沉积物捕集器捕获，通过查明单个颗粒类型的遗传成分，其特征将与其在表层群落中的来源直接相关。将从凝胶层中分离单个颗粒，并对16S和18S rRNA基因片段进行扩增和测序。这项工作将首次将联合收割机分子方法与特定颗粒的观察相结合，以便能够同时确定哪些生物体被输出以及导致其输出的过程。