food web models will be evaluated and modified in order to develop nutrient-food web responses 
incorporating classification schemes. 
4. We will develop common approaches across Divisions for parameters related to food web 
shifts (e.g., HPIX pigment analysis, stable isotope measurements, community metrics). We will 
select common methods, parameters, and measurement endpoints for food web response to 
excess nutrients when available, so that data and models are interchangeable across Divisions 
and regions, which will provide the basis for comparison and testing of our models, methods, and 
classification schemes. 
5. Testing of the proposed classification scheme and models will provide the scientific basis for 
development of nutrient criteria and/or TMDLs based on nutrient load-food web response for 
different classes of receiving waters. 
Initial research projects adopted by all four Ecology Divisions, to collect data for identifying 
potential assessment endpoints or testing classification schemes and models, will help in the 
development of a better understanding of the processes leading to shifts in food webs and help 
identify factors and parameters in common with the process. Comparison of results and 
application of successful techniques across Divisions will speed identification of practical 
assessment endpoints and development of models and understanding of food web-nutrient 
relationships. We plan to use stable isotope measurements in systems with various types of 
dominant primary producers at the base of the food web (i.e., pelagic phytoplankton, saltmarsh, 
benthic algae, and SAV). Indices that we plan to predict include ascendancy and/or flow 
diversity. This indice predicts the relative stability of food webs. System with low flow diversity 
tend to have large temporal variations in structure, usually at the lower tropic levels, but 
sometimes at the mid and high tropic levels. In the long-term, these systems eventually come to 
a new stable state that may be more eutrophic than the original food web. Hence, we can predict 
what systems are at risk (unstable) even though no model can reliably predict species succession. 
Nutrients as a stressor can reduce food web flow diversity and the ensuing systems instability 
may result in HABs, macroalgae, and other harmful species. With sufficient data in the various 
system types, we can use optimization techniques to correlate changes in flow diversity (stability) 
with nutrient load. 
WED-Food web models will be developed that track nutrient and carbon flow through aquatic 
systems using a combination of stable isotope and population level data. This is a community 
level model designed specifically to identify critical food web interactions that lead to changes in 
species diversity, commercial harvest, eutrophication, and other factors that could effect the 
designated use of a habitat. This stable isotope based model will be used to compare energy flow 
in the different types of coastal systems where each of the Divisions are located. Application of 
this model across all four Divisions will provide insight into carbon and nutrient processing 
across a wide variety of systems. 
GED-Will provide stable isotopre measurements to test the WED food web model and will focus 
on factors controlling shifts in the phytoplankton community structure and size in Escambia Bay, 
FL, which is dominated by pico-cyanobacteria blooms in summer. Size of phytoplankton is an 
important factor that determines the structuring of both the pelagic and benthic food webs. 
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