United States
                   Environmental Protection
                   Agency
                                             Office of Research
                                             and Development
                                             Washington, DC 20460
EPA/620/R-02/001f
May, 2003
HEPA   Coastal    Communications
                       Development of Nitrogen Loading-Response Models
                            for Northeast U.S.  Estuaries
Background and Goal
Human activities have dramatically changed the quantity, distribution, and movement of nutrients (e.g.,
nitrogen, phosphorus, silica) entering coastal environments.  This has affected both human health and the
environment. For example, increased algal levels due to nutrient enrichment are principally responsible for:
(1) changes in basic food webs including altered algal communities (e.g., harmful or nuisance algal blooms),
which can lead to loss of both commercially important fisheries and overall aquatic biodiversity; (2) loss of
natural submerged aquatic vegetation (SAV) habitats, which are important to  fish and other  biota; and (3)
hypoxia (or anoxia) leading to fish kills and/or
                                                        NY
                                                       Figure 1 Map showing study systems sampled
degraded benthic (bottom) habitats that affect
shellfish and other biota.

Existing models that describe relationships between
nutrient loading and environmental effects are
available for only a few well-studied systems. There
is a need to develop models that predict the adverse
effects of nutrient enrichment on systems with
limited data. Together with EPA's&ulf, Mid-
Continent, and Western Ecology Divisions, the
Atlantic Ecology Division (AED) is participating in a
multi-year National Aquatic Stressors Research Program to develop regional nutrient loading-response
models for estuarine and 
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