A suite of ecosystem response models is being developed for Lake Michigan that link inputs 
from tributanes to their associated large receiving water bodies and ecological responses. The 
construct is best described as mechanistic, mass balance models, and the primary suite of coupled 
and linked models being applied include: atmospheric, meteorological, hydrodynamic, sediment 
transport, eutrophication, sorbent dynamics, water quality transport and fate, and food chain 
bioaccumulation. The modeling focuses on establishing relationships of contaminant and 
nutrient loadings and ambient concentrations with chlorophyll, DO, N/P ratios, phytoplankton 
species composition, lower food chain produaivity, water column transparency, habitat, fish 
consumption advisories, and lake trout egg hatchability. These models improve the predictive 
ability for forecasting environmental benefits of specific load reduction scenarios of nutrients and 
contaminants, as well as the time to realize those benefits. 
2. Shallow Estuarine ^sterns in the Northeast Atlantic. 
A case study is proposed by AED to quantify the endpoint parameters being proposed in the 
Habitat Alteration, Nutrients, and Toxic Chemicals implementation plans (see Sections 4, 5, and 
7, respectively), integrate the results within the conceptual framework proposed in this Section, 
and use this information to test the utility of stressor-response relationships and diagnostic 
methods and models under development The initial research studies will be carried out within 
the coastal ecosystems of the Northeastern U.S., particularly the Narragansett Bay and 
neighboring coastal systems in Regions 1 and 2 at sites listed for TMDL development. 
Two stressors will be emphasized initially: nutrients and toxic chemicals. Several related 
projects will examine the effects of a range of nutrient loadings on several different coastal 
ecosystems, (e.g., marshes, shallow coves, and small estuaries) through field studies and model 
development. Concurrently, another project will study the effects of several classes of toxic 
chemicals on organisms, ix)pulations, and communities that dwell in critical habitats along a 
salinity gradient from fresh to salt water. Each investigation will synthesize data in a manner that 
allows us to characterize the contribution of each stressor to adverse ecological effects. For 
example, a collaborative effort between MED and AED will seek to link cause and effect 
relationships observed in laboratory to field effects using micro/mesocosm simulations. These 
studies will be integrated through an ecological model that examines the individual and 
interactive effects of nutrients and specific toxic chemicals on important habitats. This model 
will be validated by laboratory and field studies of systems where both nutrients and toxic 
chemicals are thought to be responsible for observed conditions. 
3. Shallow Estuarine Systems in the Gulf of Mexico. 
A case study is proposed by GED to quantify the endpoint parameters being proposed in Sections 
4. 5, and 7, respectively, integrate the results within the conceptual framework proposed in this 
Section, and use this information to test the utility of stressor-response relationships and 
diagnostic methods and models under development. The initial research studies will be carried 
out within the coastal ecosystems of the Gulf of Mexico, particularly the Pensacola Bay and 
neighboring coastal systems in Regions 4 and 6. 
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