Impact of Episodic Transport and Resuspension on Coastal Phytoplankton Processes: A Case Study of Lake Michigan Recurrent Coastal Plume

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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 understanding of ecophysiological mechanisms controlling phytoplankton and community structure during episodic, physical forcing events within the Great Lakes. The measurement of cellular, species, group, and community processes coupled with state- of-the-art, bio-optical instrumentation will allow for a unique comprehensive examination of the taxon-specific and community responses to distinct physical forcing factors. Work will also further develop, evaluate, and improve the current bio-optical production model for Lake Michigan and assist in efforts to develop fresh water remote-sensing algorithms.