Benthic Responses to Seasonal Carbon Inputs: Size-partioned Remineralization on Two Arctic Continental Shelves

建议提要：高纬度大陆架展示了世界上海洋中初级生产力、渔业产量和底栖动物丰度的一些最高水平。这些观测与太阳辐射的显著季节性、海冰动力学以及异常紧密的海底-海洋耦合密切相关。最近的气候模型预测，全球气候变化将在北极地区更加明显，这表明在很大程度上受冰盖季节性影响的生态系统在气温变暖的情况下可能会有不同的功能。极地大陆架底栖动物的营养主要来自两个来源：浮游植物和冰藻，每种都显示出不同的季节高峰。从真光层到海底的植物碎屑的数量，以及底栖动物对该有机通量的响应，取决于初级生产力制度、脉冲沉积的时间和藻类来源。北极的沉积物群落可以快速循环新沉积的浮游植物；有一些证据表明，它们也能迅速处理冰藻。这种再矿化如何在底栖生物群落的不同组成部分(从细菌到移动的大型动物)之间分配，已经被认为是不同的，这取决于系统是寡养型还是更具MES/E型营养。因此，为了了解底栖动物在北极生物地球化学循环中的作用，重要的是：确定北极两个地点到海底的植物碎屑通量的变异性如何影响沉积物中不稳定食物的分布，以及不同大小的底栖动物类别如何对食物供应作出反应。大多数针对这些问题的研究都是在一年周期的一小部分时间内进行的，通常是在夏季。这项研究是第一次在整个年度周期中对不同据称生产率水平的地点进行这些过程的调查。这项研究将利用一个独特的机会。目前有几个国际研究项目研究北极的碳循环。加拿大北冰洋大陆架交换研究和挪威/欧盟资助的CABANERA项目(气候变化时期巴伦支海北部的碳通量和生态系统反馈)项目已同意在研究的第4季和第3季为该项目提供泊位。在贫营养的波弗特海(CALES)和中营养的巴伦支海(CABANERA)，将对表层沉积物进行采样，以确定输入到底栖动物的植物碎屑的时空变异性。对沉积物色素的高效液相色谱分析将有助于确定有害藻类的来源。底栖动物群落不同组成部分的耗氧量将通过全核心孵化、小瓶孵化(对于微型生物群和微型生物群)和整个生物体孵化(对于底栖大型动物)来确定。表层动物物种的密度将使用投放相机来确定；这些估计将有助于确定底栖动物的这一组成部分对沉积物群落总耗氧量的重要性。与多名研究人员从不同的角度研究相同的一般性问题的价值怎么估计都不为过。例如，两个航次的同事将描述底栖生物群落结构、沉积物中的亚缺氧和无氧呼吸途径，以及碳通量。此外，在这些项目的多学科组织下，将提供有关大气、冰和水柱过程的数据。该项目的一个组成部分将提供更广泛的影响，超出即将进行的研究的科学价值。北极研究本身是耐人寻味的，并带有一种神秘感。研究巡游提供了展示国家和州科学标准中突出的要素的机会：科学方法，以及科学技术及其社会应用的整合。与一名海洋赠款教育专家合作，将为K-12教育工作者制作一张CD-ROM，其中将包含照片、数据、图表、关于科学主题、动物和地理的补充信息，以及对科学家、船员和学生的采访。这张光盘将分发给教师，帮助他们更新不同学科的现有教案或创建新的教案。

Synopsis of proposal:High latitude continental shelves exhibit some of the highest levels of primary productivity, fisheries production, and benthic faunal abundances found in the world.s oceans. These observations are tightly linked to pronounced seasonality in solar radiation, sea-ice dynamics, and unusually tight benthic-pelagic coupling. Recent climate models predict that global climate change will be more pronounced in Arctic regions, suggesting that ecosystems shaped in large part by seasonality in ice cover may function differently under warmer temperature regimes. Continental shelf benthos in polar regions derive nutrition from two main sources: phytoplankton and ice algae, each displaying distinct seasonal maxima. The amount of phytodetritus from the euphotic zone reaching the sea floor, and the benthic response to that organic flux, is dependent on primary productivity regime, timing of pulsed deposition, and algal source. Sediment communities in the Arctic can rapidly cycle newly-deposited phytoplankton; and there is some evidence that they also quickly process ice algae. How this remineralization is partitioned among different components of the benthic community (from bacteria to mobile megafauna) has been suggested to vary depending upon whether the system is oligotrophic or more mes-/eu- trophic. To understand the role of the benthos in biogeochemical cycling in the Arctic, therefore, it is important to: determine how variability in phytodetrital flux to the sea floor at two Arctic sites affects the distribution of labile food in the sediments, and how different size classes of benthic fauna respond to food supply. Most of the studies addressing these questions have been performed over a small fraction of the annual cycle, usually well into the summer season. This study is the first to investigate these processes over the entire annual cycle at sites different in purported productivity levels. This study will take advantage of a unique opportunity. There are currently several international research programs studying carbon cycling in the Arctic. The Canadian Arctic Shelf Exchange Study (CASES) and the Norwegian/EU-funded CABANERA (CArbon flux and ecosystem feedback in the northern BAreNts Sea in an ERA of Climate Change) project have agreed to provide berth space for this project during the 4 (CASES) and 3 (CABANERA) seasons of the respective studies. In the oligotrophic Beaufort Sea (CASES) and the mesotrophic Barents Sea (CABANERA), surface sediments will be sampled to determine the spatial and temporal variability in phytodetrital input to the benthos. HPLC analysis of sediment pigments will help determine the sources of the algal detrititus. Oxygen consumption by different components of the benthic community will be determined by whole-core incubations, microvial incubations (for meio- and micro- biota), and whole organism incubations (for epibenthic megafauna). Densities of epifaunal species will be determined using a drop-camera; and these estimates will help determine the importance of this component of the benthos to total sediment-community oxygen consumption. The value of collaborating with multiple researchers studying the same general questions from different perspectives cannot be overestimated. For example, colleagues on both cruises will be describing benthic community structure, suboxic and anaerobic respiration pathways in the sediments, and carbon flux values. Additionally, data on atmospheric, ice, and water column processes will be available under the multidisciplinary organization of these projects. One component of this project will provide a broader impact, beyond the scientific value of the research to be conducted. Arctic research itself is intriguing, and carries with it a sense of mystery. Research cruises present opportunities to demonstrate elements that are prominent in national and state science standards: the scientific method, and the integration of science and technology and its societal applications. In collaboration with a Sea Grant Education Specialist, a CD-ROM will be produced for K-12 educators that will contain photographs; data; graphs; supplemental information about scientific topics, fauna, and geography; and interviews with scientists, crew, and students. This CD-ROM will be distributed to teachers to help them update existing or create new lesson plans in a variety of disciplines.