various ecosystem classification approaches, up to and including the watershed scale. At the 
same time, current criteria, methods, and approaches for stressors need to be improved where 
major uncertainties exist, or developed for others where information is scarce. Finally, all 
aquatic stressor research elements from this process need to be combined to develop management 
strategies to protect the ecological integrity of aquatic ecosystems. A series of EPA workshops 
and workgroup meetings has identified five main research products for meeting this goal: 
• Methods to predict biological effects of habitat alteration; 
• Population, community, and ecosystem stressor-response models; 
• Diagnostic tools to determine impairment or causes of impairment to aquatic systems; 
• Classification approaches to aid in the prediction and management of problems; and 
• Methods and models to support development of ecological criteria. 
In some cases, these products are under development, but in others, development has not yet 
begun. Sections 4-8 of this document provide the plans for implementing research in each of 
NHEERL’s priority areas. 
Section 4 focuses on quantifying the life support functions of specific habitat and habitat 
complexes to predict the biological effects of habitat alteration and/or loss on populations of fish, 
shellfish, and wildlife. The main goal of this research is to quantify the role of habitat in 
maintaining healthy aquatic and aquatic-dependent populations by 1) describing the relationships 
between habitat and biota at the appropriate scales to quantify effects on population endpoints 
due to habitat alteration and 2) synthesizing the cumulative support function of individual 
habitats and aquatic ecosystems, and integrating habitat alteration effects with effects from other 
stressors. Necessary elements of this research include providing: suites of species endpoints, 
assessment and measurement endpoints and strategies, habitat alteration-population response 
relationships, classification schemes, and models for extrapolating data across spacial scales. 
Research projects in this plan deal specifically with coastal vegetated habitat; shoreline, lake, and 
estuary scale habitat; and landscape scale habitat. 
Section 5 centers on understanding the responses of receiving waters to excess nutrients. The 
main goal of this research is to define and quantify relationships between nutrient loading and 
ecological responses for different aquatic resource types to develop the basis for deriving 
numeric nutrient criteria. Principal components of this research include providing conceptual 
models for specific assessment endpoints, a state of the science evaluation to develop and 
improve nutrient-load responses, classification schemes, standard measurement endpoints, and 
nutrient load-response models. Research projects in this plan deal primarily with coastal 
receiving waters and the development of nutrient load-response relationships for dissolved 
oxygen, submerged aquatic vegetation, and food web and community composition changes. 
Section 6 deals with the direct and indirect effects of suspended and bedded sediments in aquatic 
ecosystems. The primary goal of this research is to provide and demonstrate the approach for 
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