Nutrient and Lower Food Web Dynamics:
A Coupled Biological and Physical Modeling Study

C. Chen

NOAA CoastWatch satellite imagery has revealed a highly reflective, recurrent coastal plume during springtime in southern Lake Michigan (so called the Lake Michigan Recurrent Coastal Plume: LMRCP). To identify and qualify the influences of the formation, evolution, and perturbation of this plume on chemical and biological processes, a series of field measurements are proposed to be conducted across and along the LMRCP before, during, and after plume formation. The objectives of these field measurements are to (1) estimate the population structures and species abundance of microbial food web organisms (Gardner and Lavrentyev proposal), (2) determine the quantity, phases, losses, abiotic and biotic uptakes, and regeneration of phosphorus due to sediment resuspension and settling of plume particles and plankton and their impacts on phytoplankton and bacterioplankton growth and nutrient limitation (Cotner et al. proposal), (3) estimate the population structure, life-stage species distribution and abundances, behavior, and species-specific reproductive and grazing rates of adult and juvenil copepods (Bundy et al. proposal), and (4) provide a quantitative value of phytoplankton primary production (Fahanenstial et al. proposal) and sediment-trap collections (Eadie et al. proposal).
The objective of this modeling proposal is to address the primary hypothesis that the effects of episodic meteorological events on biological productivity and chemical transformation are mainly through the modification of (1) the cross-margin and vertical transports of momentum, solutes, particulates, and organisms, (2) turbulent mixing, and (3) light limitation. To test this hypothesis, we propose to collaborate with Schwab and Beletsky (physical model group), Bundy, Cotner, Eadie, Fahanenstial, Gardner, and Lavrentyev (biological observational group) to couple a lower trophic level biological model into a full three-dimensional hydrodynamic model (a modified version of Princeton Ocean Model (POM) with application to Lake Michigan. This coupled model will be used to (1) integrate the results of physical and biological investigations in the Episodic Events Proposal and (2) interpret the field observations by model-guide mechanism studies of a coupled physical, chemical, and biological ecosystem. Numerical experiments will be focused on nonlinear interactions of biological, chemical, and physical processes associated with strong wind mixing, ice-melting, upwelling/downwelling, and eddy formation within and at edge of the. The model results will contribute to developing a comprehensive understanding of the effects of the LMRCP on food web dynamics in southern Lake Michigan.