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“涡流”(涡流动力学、混合输出和物种组成)项目的一个配套项目。这一跨学科实地方案将于2004年和2005年夏季在马尾藻海启动。最近的证据表明，中尺度涡旋是主要副热带涡旋低营养水域的一种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，涡流驱动的营养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具有间歇性，因此对这一过程的直接观察相对较少。现有数据表明，与某些类型的涡旋相关的等径位移可以将营养物质输送到真光层，导致上覆水域中的叶绿素积累。这项提议中包含的初步数据表明，与BATS现场的气旋涡旋相吻合，细菌产量相对于月平均值有显著提高。然而，原核生物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未阐明。这个配套项目建议对中尺度涡旋中与异养原核生物相关的参数进行采样，记录这些参数在涡旋内部如何通过时间和空间(水平和垂直)相对于外部(控制)变化。沃特斯。具体来说，PI建议：1.通过比较中尺度特征内外700米表层的种群和速率，评估原核生物生物量和生产率在涡流诱导的营养泵作用下的时空变异性。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)的生物有效性以及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微生物过程与自由生活微生物过程的分配。4.确定中尺度扰动和由此引起的生物地球化学变化是否导致原核生物群落结构的变化。这些测量的智力价值汇编将提供对异养原核生物对涡旋水华环境有机物质状况的响应的严格评估。原核生物在决定水华的生物地球化学命运中起着重要作用。亚热带环流的低营养水域的典型特征是元素通过微生物循环广泛循环，但很少出口。随着生物对涡流诱导的营养物质泵送的响应，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于深入了解这些特征中的生态反应和生物地球化学过程将是重要的。我们的测量将补充和加强对基金涡旋计划收集的各种参数的同时评估。更广泛的影响这项建议的更广泛的影响部分包括四个具体目标：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一个集中的.EDIES网站、BATS和微生物观测站网站以及UCSB海洋科学研究所网络和实验室的网络推广计划；以及4)将海上实地工作经验纳入UCSB女性科学与工程专业(WISE)导师计划，旨在保持本科女性在科学界的地位。

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.