Collaborative Research: Plankton Community Structure and Iron Distribution in the Southern Drake Passage

合作研究：德雷克海峡南部浮游生物群落结构和铁分布

• 批准号: 0230443
• 负责人: B. Gregory Mitchell
• 金额: $ 73.65万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 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: 2003-07-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0230443&HistoricalAwards=false
• 关键词: Collaborative; Research; Plankton; Community; Structure

The Shackleton Fracture Zone (SFZ) in the Drake Passage defines a boundary between low and high phytoplankton waters. West of Drake Passage, Southern Ocean waters south of the Polar Front and north of the Antarctic continent shelf have very low satellite-derived surface chlorophyll concentrations. Chlorophyll and mesoscale eddy kinetic energy are higher east of SFZ compared to values west of the ridge. In situ data from a 10-year survey of the region as part of the National Marine Fisheries Service's Antarctic Marine Living Resources program confirm the existence of a strong hydrographic and chlorophyll gradient in the region. An interdisciplinary team of scientists hypothesizes that bathymetry, including the 2000 m deep SFZ, influences mesoscale circulation and transport of iron leading to the observed phytoplankton patterns. To address thishypothesis, the team proposes to examine phytoplankton and bacterial physiological states (including responses to iron enrichment) and structure of the plankton communities from virus to zooplankton, the concentration and distribution of Fe, Mn, and Al, and mesoscale flow patterns near the SFZ. Relationships between iron concentrations and phytoplankton characteristics will be examined in the context of the mesoscale transport of trace nutrients to determine how much of the observed variability in phytoplankton biomass can be attributed to iron supply, and to determine the most important sources of iron to pelagic waters east of the Drake Passage. The goal is to better understand how plankton productivity and community structure in the Southern Ocean are affected by the coupling between bathymetry, mesoscale circulation, and limiting nutrient distributions.The research program includes rapid surface surveys of chemical, plankton, and hydrographic properties complemented by a mesoscale station grid for vertical profiles, water sampling, and bottle incubation enrichment experiments. Distributions of manganese and aluminum will be determined to help distinguish aeolian, continental shelf and upwelling sources of iron. The physiological state of the phytoplankton will be monitored by active fluorescence methods sensitive to the effects of iron limitation. Mass concentrations of pigment, carbon and nitrogen will be obtained by analysis of filtered samples, cell size distributions by flow cytometry, and species identification by microscopy. Primary production and photosynthesis parameters (absorption, quantum yields, variable fluorescence) will be measured on depth profiles, during surface surveys and on bulk samples from enrichment experiments. Viruses and bacteria will be examined for abundances, and bacterial production will be assessed in terms of whether it is limited by either iron or organic carbon sources. The proposed work will improve our understanding of processes controlling distributions of iron and the response of plankton communities in the Southern Ocean. This proposal also includes an outreach component comprised of Research Experiences for Undergraduates (REU), Teachers Experiencing the Antarctic and Arctic (TEA), and the creation of an educational website and K-12 curricular modules based on the project.

德雷克海峡中的沙克尔顿断裂带（SFZ）定义了浮游植物沃茨的高低界线。在德雷克海峡以西、南极锋以南和南极大陆架以北的南大洋沃茨，卫星测得的表面叶绿素浓度非常低。叶绿素和中尺度涡动动能是较高的SFZ以东的值相比，山脊以西。作为国家海洋渔业局南极海洋生物资源计划的一部分，对该地区进行了为期10年的调查，现场数据证实该地区存在强烈的水文和叶绿素梯度。一个跨学科的科学家小组假设，水深测量，包括2000米深的SFZ，影响中尺度环流和铁的运输，导致观察到的浮游植物模式。为了解决这一假设，该团队建议检查浮游植物和细菌的生理状态（包括对铁富集的反应）和浮游生物群落的结构，从病毒到浮游动物，Fe，Mn和Al的浓度和分布，以及SFZ附近的中尺度流动模式。铁浓度和浮游植物特性之间的关系将在中尺度微量营养盐运输的背景下进行检查，以确定有多少浮游植物生物量的观测到的变化可以归因于铁的供应，并确定铁的最重要的来源，以远洋沃茨以东的德雷克海峡。其目标是更好地了解南大洋的浮游生物生产力和群落结构是如何受到水深测量、中尺度环流和限制性营养盐分布之间的耦合影响的，研究计划包括化学、浮游生物和水文特性的快速表面调查，并辅之以垂直剖面的中尺度站网格、水样采集和瓶培养富集实验。锰和铝的分布将被确定，以帮助区分风成，大陆架和上升流来源的铁。浮游植物的生理状态将通过对铁限制的影响敏感的活性荧光方法进行监测。将通过分析过滤样品、流式细胞术细胞大小分布和显微镜下物种鉴定获得色素、碳和氮的质量浓度。将在深度剖面图上、在表面勘测期间和在浓缩实验的批量样品上测量初级生产和光合作用参数（吸收、量子产率、可变荧光）。将检查病毒和细菌的丰度，并评估细菌产量是否受到铁或有机碳源的限制。拟议的工作将提高我们对控制铁分布的过程和南大洋浮游生物群落的反应的理解。该提案还包括一个外联部分，包括本科生研究经验（REU），体验南极和北极的教师（TEA），以及基于该项目创建教育网站和K-12课程模块。