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

底栖生物对季节性碳输入的响应：两个北极大陆架按尺寸划分的再矿化

• 批准号: 0326371
• 负责人: Paul Renaud
• 金额: $ 28.65万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0326371&HistoricalAwards=false
• 关键词: Benthic; Responses; Seasonal; Carbon; Inputs

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.

提案概要：高纬度大陆架展现出世界海洋中最高水平的初级生产力、渔业生产和底栖动物丰富度。 这些观测结果与太阳辐射、海冰动力学和异常紧密的底栖-中上层耦合的明显季节性密切相关。最近的气候模型预测，全球气候变化在北极地区将更加明显，这表明在很大程度上由冰盖季节性塑造的生态系统在较温暖的温度条件下可能会发挥不同的作用。 极地地区的大陆架底栖动物从两个主要来源获取营养：浮游植物和冰藻，每个来源都表现出不同的季节最大值。 从富光带到达海底的植物碎屑的量以及底栖生物对该有机通量的响应取决于初级生产力状况、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；有证据表明它们也能快速处理冰藻。 有人认为，这种再矿化在底栖群落的不同组成部分（从细菌到移动巨型动物）之间的分配方式取决于系统是贫营养还是中/富营养。 因此，要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：确定两个北极地点的海底植物碎屑通量的变化如何影响沉积物中不稳定食物的分布，以及不同大小类别的底栖动物对食物供应的反应。 大多数解决这些问题的研究都是在年度周期的一小部分时间内进行的，通常是在夏季。 这项研究首次在不同的生产力水平的地点在整个年度周期内调查这些过程。 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正在研究北极的碳循环。 加拿大北极陆架交换研究 (CASES) 和挪威/欧盟资助的 CABANERA（气候变化 ERA 中北巴伦茨海的碳通量和生态系统反馈）项目已同意在各自研究的第 4 个 (CASES) 和第 3 个 (CABANERA) 季节为本项目提供停泊空间。 在贫营养的波弗特海 (CASES) 和中营养的巴伦支海 (CABANERA)，将对表层沉积物进行采样，以确定输入到底栖植物的植物碎屑的空间和时间变化。 沉积物色素的 HPLC 分析将有助于确定藻类碎屑的来源。 底栖群落不同组成部分的耗氧量将由整体核心孵化、微瓶孵化（对于小型生物群和微生物群）和整个生物体孵化（对于表层巨型动物）来确定。 将使用水滴相机确定表层动物物种的密度；这些估计将有助于确定底栖生物的这一组成部分对沉积物群落总耗氧量的重要性。 与多个研究人员合作从不同角度研究相同的一般问题的价值怎么估计都不为过。 例如，两次航行的同事将描述底栖群落结构、沉积物中的低氧和无氧呼吸途径以及碳通量值。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产生更广泛的影响，超出所进行研究的科学价值。北极研究本身就很有趣，并且带有神秘感。 研究巡航提供了展示国家和州科学标准中突出要素的机会：科学方法以及科学技术及其社会应用的整合。 与 Sea Grant 教育专家合作，将为 K-12 教育工作者制作一张包含照片的 CD-ROM；数据;图表；有关科学主题、动物群和地理的补充信息；以及对科学家、船员和学生的采访。 该 CD-ROM 将分发给教师，以帮助他们更新各个学科的现有课程计划或创建新的课程计划。