The Effects of a Recurrent Spring Plume on the Dynamics and Structure of the Lower Food Web in Southern Lake Michigan

9726681加德纳研究将响应五大湖海岸研究机会(NSF97-38)的宣布而进行。这是一个由来自十个学术和政府研究机构的研究人员合作的研究项目。这项研究是在NSF海岸海洋过程(COOP)计划和NOAA海岸海洋计划的赞助下进行的。这项为期5年的合作研究计划将侧重于偶发事件对近岸-近海运输和随后的生态后果的重要性。这项研究旨在1)确定控制五大湖沿海边缘生物、化学和地质材料跨边界(近岸到近海)运输的过程，以及2)制定和测试科学战略，以评估、量化和预测五大湖或选定的沿海分区域自然和人为多重压力的影响。在湖泊和沿海生态系统中，通过沉积物再悬浮的过程，污染沉积物和上覆水之间存在着紧密的耦合。对密歇根湖的卫星观测表明，每年都会出现近岸-近海运输的反复事件，一股10公里宽的再悬浮物质羽状物沿着密歇根湖南岸延伸超过200公里。初步证据表明，这一阶段性事件可能是密歇根湖跨界泥沙运移的主要机制。这类事件影响到五大湖生物地球化学重要物质(BIMS)的再循环、生态系统反应、跨等深线运输。该方案的结果将适用于许多沿海地区的类似事件。这项综合的跨学科研究将实施综合观测计划和数值模拟工作，以确定、量化和开发冬春季再悬浮事件的预测工具，并评估该事件对BIMS的运输和转化以及对湖泊生态的影响。这项研究的重点是在羽流形成之前、期间和之后微生物食物网生物体的结构和丰度；测量氮循环速率与羽流内、边缘和羽流外微型浮游动物的群落和特定物种的放牧速率的关系。观测、实验和结果将与初级生产和浮游动物放牧实验以及其他关于营养和物理过程的研究相协调，以完成概念模型，并为拟议的生物/物理耦合模型提供数据。

9726681 Gardner Research will be undertaken in response to an Announcement of Opportunity (NSF 97- 38)for Coastal Studies in the Great Lakes. This is a collaborative research project between investigators from ten academic and government research institutions. The research is being conducted under the auspices of the NSF Coastal Ocean Processes (CoOP) program and the NOAA Coastal Ocean Program. This collaborative, 5-year research program will focus on the importance of episodic events on nearshore-offshore transport and subsequent ecological consequences. The study seeks to 1) determine what processes control the cross-margin (inshore to offshore) transport of biological, chemical, and geological materials in the coastal margins of the Great Lakes, and to 2) develop and test scientific strategies for assessing, quantifying, and predicting the impacts of multiple stresses both natural and anthropogenic, in the Great Lakes or selected coastal sub-regions. A tight coupling between contaminated sediments and overlying water exists in lakes and coastal ecosystems through the process of sediment resuspension. Satellite observations in Lake Michigan illustrate an annually recurrent episode of nearshore-offshore transport, a 10 km wide plume of resuspended material extending over 200 km along the southern shores of the lake. Preliminary evidence indicates that this episodic event may be the major mechanism for cross-margin sediment transport in Lake Michigan. This type of event impacts recycling of biogeochemically important materials (BIMS), ecosystem responses, cross-isobath transport in the Great Lakes. The program results will be applicable to similar events in many coastal areas. This comprehensive, interdisciplinary study will implement an integrated observational program and numerical modeling effort to identify, quantify, and develop prediction tools for the winter-spring resuspension event and to assess the impact of this event on the transport and transformation of BIMS and on lake ecology. This component of the study focuses on structure and abundance of microbial food web organisms before, during, and after plume formation; measure Nitrogen cycling rates in relation to community and species-specific grazing rates of microzooplankton within, at the edge, and outside of the plume. Observations, experiments, and results will be coordinated with those from primary production and zooplankton grazing experiments and other studies of nutrient and physical processes to complete a conceptual model and provide data for the proposed coupled biological/physical model.