The effect of mesoscale eddy perturbations on microbial processes and community structure in the Sargasso Sea

该提案奖将作为由NSF生物、化学和物理海洋学资助的“EDDY”（EDDY动力学、混合出口和物种组成）项目的伙伴项目。这个跨学科的实地项目将于2004年和2005年夏天在马尾藻海启动。近年来的证据表明，中尺度涡旋是副热带主要环流少营养水域中重要的营养物质输送机制。数值模拟和基于卫星的统计估计表明，涡旋驱动的养分通量的大小可能足以平衡对新产量的地球化学估计。由于驱动这一过程的事件在空间和时间上的间歇性，对这一过程的直接观测相对较少。现有数据表明，与某些类型的漩涡相关的等环流位移可以将营养物质运送到光区，导致叶绿素在上覆水域积累。初步数据表明，与气旋涡旋的通过相一致，BATS站点的细菌产量相对于月平均值显着提高。然而，原核异养反应的程度及其对耦合生物地球化学循环和出口的影响尚不清楚。该合作项目建议取样与中尺度涡旋有关的异养原核生物参数，记录这些参数在涡旋内相对于外部（对照）水域如何随时间和空间（水平和垂直）变化。具体来说，pi建议：1。通过比较地表700米、中尺度特征内外的储量和速率，评估响应涡激营养物泵送的原核生物生物量和生产速率的时空变异性。2. 确定中尺度涡旋扰动和随后的养分泵送是否影响新产生的溶解有机物（DOM）的生物利用度和原核生物群落处理它的效率。3. 评估涡流诱导的营养泵如何影响附着与自由生活的微生物过程的分配。4. 确定中尺度扰动和由此引起的生物地球化学变化是否会导致原核生物群落结构的变化。这些测量值的汇编将提供对异养原核生物对涡旋水华环境的有机物制度的反应的严格评估。原核生物在决定藻华的生物地球化学命运方面起着重要作用。副热带环流少营养水体的典型特征是通过微生物循环大量回收元素，而很少输出。当生物学对涡流诱导的营养泵送作出反应时，记录异养原核生物处理新鲜产生的有机物的速度和效率将是重要的，以便更好地了解这些中尺度特征中的碳和能量流动。监测原核生物群落结构对了解这些特征中的生态响应和生物地球化学过程具有重要意义。我们的测量将补充和加强对EDDIES项目所收集的各种参数的并发评估。更广泛的影响本提案的更广泛影响部分包含四个具体目标：1)参与和支持博士后研究员以及本科生实验室助理，2)UCSB的课程开发，3)将微生物数据集整合到集中的。eddies中基于网络的外展计划。网站、BATS和微生物观测站网站以及UCSB海洋科学研究所基于网络和实验室的外展计划；4)将海上实地考察经验纳入UCSB女性科学与工程（WISE）指导计划，旨在保持本科女性从事科学研究。

This proposal award will serve as a companion project to the "EDDIES" (EDDY Dynamics, mixing Export, and Species composition) project funded by NSF Biological, Chemical and Physical Oceanography. This interdisciplinary field program will be initiated in the Sargasso Sea during the summer of 2004 and 2005. Recent evidence suggests that mesoscale eddies are an important nutrient transport mechanism in the oligotrophic waters of the main subtropical gyres. Numerical simulations and satellite-based statistical estimates indicate that the magnitude of the eddy-driven nutrient flux could be sufficient to balance geochemical estimates of new production. Relatively few direct observations of this process are available, owing to the spatial and temporal intermittency of the events that drive it. Available data demonstrate that isopycnal displacements associated with certain types of eddies can transport nutrients into the euphotic zone, resulting in the accumulation of chlorophyll in overlying waters. Preliminary data, included in this proposal, indicate that coincident with the passage of a cyclonic eddy at the BATS site, bacterial production rates were significantly enhanced relative to the monthly mean values. However, the extent of the prokaryotic heterotrophic response and their impact on coupled biogeochemical cycles and export has yet to be elucidated. This companion project proposes to sample parameters relevant to heterotrophic prokaryotes across mesoscale eddies documenting how these parameters vary inside the eddy through time and space (horizontal and vertical) relative to outside (.control.) waters. Specifically the PIs propose to: 1. Assess the spatial and temporal variability of prokaryotic biomass and production rates in response to eddy induced nutrient pumping by comparing stocks and rates throughout the surface 700 m, in and out of the mesoscale feature. 2. Determine if a mesoscale eddy perturbation and subsequent nutrient pumping affects the bioavailability of newly produced dissolved organic matter (DOM) and the efficiency with which the prokaryotic community processes it. 3. Assess how eddy induced nutrient pumping may affect the partitioning of attached versus free-living microbial processes. 4. Determine if the mesoscale perturbation and the resulting changes in biogeochemistry lead to a change in the prokaryotic community structure. Intellectual Merit Compilation of these measurements will provide a rigorous assessment of the response of heterotrophic prokaryotes to the organic matter regime of the eddy bloom environment. Prokaryotes play an important role in determining the biogeochemical fate of a bloom. The oligotrophic waters of subtropical gyres are typically characterized by extensive recycling of elements through the microbial loop with little export. As biology responds to the eddy-induced nutrient pumping it will be important to document the rate and efficiency by which heterotrophic prokaryotes process freshly produced organic matter in order to better understand the flow of carbon and energy in these mesoscale features. Monitoring the prokaryotic community structure will be important to gain insight to the ecological response and biogeochemical processing within these features. Our measurements will complement and strengthen concurrent assessments of various parameters collected by the funded EDDIES program. Broader Impacts There are four specific objectives incorporated into the broader impacts portion of this proposal: 1) Participation and support for a post-doctoral fellow as well as undergraduate laboratory assistants, 2) Curricular development at UCSB, 3) Web-based outreach programs integrating the microbial data set into a centralized .EDDIES. website, the BATS and Microbial Observatories websites as well as the UCSB Marine Science Institute web- and laboratory-based outreach programs, and 4) Integration of fieldwork at sea experiences into the UCSB Women in Science and Engineering (WISE) mentorship program targeted at keeping undergraduate women in the sciences.