Influences of suspended sediments on the ecosystem in Lake Michigan: a 3-D coupled bio-physical modeling experiment

Abstract

The influence of suspended sediments on the Lake Michigan ecosystem was examined using a 3-dimensional (3-D) coupled biological and physical model developed by Chen et al. (part I). The model was driven by the realistic meteorological forces observed in March 1998, with daily inputs of suspended sediment concentration that were derived from temporally and spatially interpolated satellite imagery. The model results show the significant impact of a seasonally recurring coastal resuspension plume on the spatial and temporal variation of the nutrients and plankton in southern Lake Michigan. The plume-released nutrients played an essential role in maintaining the nutrient level in the lake. Although the growth of phytoplankton in the plume depended on the availability of nutrients and light, the offshore decrease in phytoplankton biomass still satisfied the Sverdrup's relationship. Cross-shore fluxes of nutrients and phytoplankton were controlled by episodic wind events with a period of : 5 -7 days: offshore during southward winds and onshore during northward winds. The flux estimates for biological variables suggest that the microbial food web is a key contributor to secondary production in southern Lake Michigan and the lower trophic level food web system could be dynamically divided into two decoupled loops: (1) detritus-bacteria-microzooplankton-large zooplankton; and (2) nutrient-phytoplankton-detritus. The model-predicted spatial distributions of nutrients and phytoplankton were in reasonable agreement with observations taken during the 1998 EEGLE interdisciplinary cruises, suggesting that the model was sufficiently robust to capture the basic characteristics of the Lake Michigan ecosystem during the plume event.

Anatomy of the recurrent coastal sediment plume in Lake Michigan and its impacts on light climate, nutrients, and plankton

“…Other symbols refer to station locations where water samples were collected. phytoplankton-zooplankton model to predict plume impacts [Chen et al, 2004a[Chen et al, , 2004bJi et al, 2002].…”

“…Observations during nonplume periods were designed to serve as controls for plume observations. Some of these observations provided data for a modeling effort that described influences of suspended sediments on the ecosystem [Ji et al, 2002;Chen et al, 2004aChen et al, , 2004b and for investigations of plume impacts on bacterial production , the microbial food web Biddanda and Cotner, 2002] (also P. J. Lavrentyev et al, Microzooplankton response to mesoscale episodic events in Lake Michigan, unpublished manuscript, 2007) (hereinafter referred to as Lavrentyev et al, unpublished manuscript, 2007), and phytoplankton [Millie et al, 2002[Millie et al, , 2003. Consistent with EEGLE hypotheses, earlier reported impacts of the plume have been the injection of dissolved organic carbon (DOC) and particulate organic carbon (POC) that have stimulated heterotrophic production and the microbial food web growth Biddanda and Cotner, 2002;Lavrentyev et al, unpublished manuscript, 2007] and resuspended sediments that decreased light intensity and thereby limited phytoplankton growth [Millie et al, 2002[Millie et al, , 2003.…”

A model study of the coupled biological and physical dynamics in Lake Michigan

“…1) for 1994-1995. A 3-D experiment, with focus of the impact of seasonally recurring coastal suspended sediment plume on the spatial distribution of the plankton in southern Lake Michigan, is presented in a separate paper in this volume (Ji et al, 2002).…”

Winter storms: Sequential sediment traps record Daphnia ephippial production,resuspension, and sediment interactions

“…In the late 1980s, coastal zone color scanner (CZCS) imagery revealed a 10-km wide plume of resuspended sediment that extended over 100 km along the southern shore, following the cyclonic gyre (Mortimer 1988). Since becoming routinely available in 1992, advanced very high resolution radiometer (AVHRR, NOAA TIROS-N series, NOAA-10 and NOAA-11) imagery has confirmed coastal sediment plumes every year in MarchApril, although the spatial extent and duration varies greatly from year to year (Chen et al 2002;Ji et al 2002).…”