Collaborative Research: The Role of Microbial Food Webs in Carbon Fluxes and Shelf-Basin Exchange in the Arctic Ocean

陆架-盆地相互作用（SBI）项目和其他大型多学科项目最近完成了对北冰洋碳循环的实地考察。这些项目包括测量微生物存量和产量，因为微生物在构建海洋食物网和调节海洋中无机和有机碳的通量方面具有根本的重要性。据推测，与大多数海洋环境相比，高纬度海洋中的异养细菌和其他微生物循环的初级生产较少，因为常年的冷水抑制了微生物的活动。来自SBI计划的一些数据表明，北极西部通过微生物循环的碳通量低于温暖的海洋系统，而其他数据表明有机碳的降解速度超过了初级生产的速度。这些观测结果对我们理解北极大陆架生产性水域和有机碳贫乏盆地之间的碳输出和交换具有重要意义。然而，关于数据的有效性和解释、SBI发现的普遍性以及微生物过程对北极碳系统的影响等几个尚未解决的问题仍然存在。为了解决这些问题，这项工作将审查下列问题：在北冰洋不同地区，通过微生物环的能量流结构是怎样的？将分析来自SBI和其他北极研究的所有关于微生物和相关生物地球化学参数的数据，以便组成一个泛北极综合，并确定北冰洋生态系统各区域之间可能的联系。微生物活动对北极西部碳系统的影响是什么？微生物率将与根据北极西部DIC和DOC的时空变化估计的净群落产量和DOM输出率进行比较。在北冰洋有机物的生产和降解过程中，运输的作用是什么？一个明确的、三维的北冰洋环流和生物地球化学模型将被用来评估运输在生产和呼吸的时空解耦中的作用。这项工作将有助于最大限度地利用SBI和其他项目收集的数据集，其中许多数据集尚未得到彻底的分析和综合。此外，数据综合和建模工作将提供一个框架，以考虑气候变化如何影响北极的碳通量和食物网动态。这种综合将是衡量这一重要生态系统潜在变化轨迹的一个重要里程碑。

The Shelf-Basin Interaction (SBI) program and other large, multi-disciplinary projects have recently completed field work to examine carbon cycling in the Arctic Ocean. These programs included measurements of microbial standing stocks and production because of the fundamental importance of microbes in structuring marine food webs and in modulating fluxes of inorganic and organic carbon in the oceans. It has been hypothesized that heterotrophic bacteria and the rest of the microbial loop process less primary production in high latitude oceans than in most oceanic regimes because perennially cold water inhibits microbial activity. Some of the data from the SBI program indicate that the flux of carbon through the microbial loop is lower in the western Arctic than in warmer marine systems, whereas other data indicate organic carbon degradation exceeds rates of primary production. These observations have major implications for our understanding of carbon export and exchange between productive shelf waters and organic carbon-poor basins of the Arctic. However, several unresolved issues remain about the validity and interpretation of the data, the generality of the SBI findings, and the impact of microbial processes on the Arctic carbon system.To address these issues, this effort will examine the following questions:1. What is the structure of energy flow through the microbial loop in various regions of the Arctic Ocean?All data on microbes and related biogeochemical parameters from SBI and other Arctic studies will be analyzed in order to compose a pan-Arctic synthesis and to identify possible linkages between regions of the Arctic Ocean ecosystem.2. What is the impact of microbial activity on the carbon system in the western Arctic?Microbial rates will be compared with rates of net community production and DOM export as estimated from temporal and spatial variations in DIC and DOC in the western Arctic.3. What is the role of transport in decoupling the production and degradation of organic matter in the Arctic Ocean?An explicit, three dimensional model of Arctic Ocean circulation and biogeochemistry will be used to evaluate the role of transport in the spatial and temporal decoupling of production and respiration.This work will help maximize use of the datasets collected by SBI and other programs, of which much has not been thoroughly analyzed and synthesized. In addition, the data synthesis and modeling efforts will provide a framework in which to consider how climate change may affect carbon fluxes and food web dynamics in the Arctic. This synthesis will be an essential mile post for gauging the trajectory of potential changes in this important ecosystem.