which factors other than habitat limit populations. Because ecological constraints and co-factors 
independent of vegetated habitat will also determine local biological potential, there is likely to 
be a family of curves for different ecological conditions; for example, for different salinities, 
wave energy regimes, or wetland types. Assigning habitats or systems to the appropriate 
response curve will require development and evaluation of classification systems and methods 
for determining ecological potential. This work will be done with the objective of contributing to 
the larger-scale habitat considerations (described below). Therefore, achieving broad spatial 
coverages for species-habitat relationships will require stratifying response curves by ecoregion 
or latitude, devising methods for extrapolation outside the range of measured habitat types and 
co-factors, and schemes for regionalizing population endpoints when specific populations of 
interest have insufficiently broad distributions. The balance among empirical and 
mechanistic investigations will depend on the strength of the linkage among the particular 
species endpoint and the habitat, and on the spatial extent for which relationships are desired. 
For example, situations where the primary concern is a particular species with identifiable 
demographic bottlenecks that depend directly on specific, measurable habitat elements may lend 
themselves to mechanistic species-habitat relationships. For other situations, where the 
dependence on vegetated habitat is more diffuse and specific population bottlenecks cannot be 
identified or where a suite of endpoints is applied over large regions, empirical relationships may 
be more easily obtained and appropriate. 
Products 
APM 1A FY02 Listings of the high-priority species of fish, shellfish, and aquatic-dependent 
wildlife for study in each biogeographic region, and listings of the habitats that are ccxisidered to 
be critical to each (WED). 
APM 3A FY03 Penaeid shrimp dependence on seagrass habitat (GED). 
APM 3B FY03 Finfish dependence on seagrass and oyster reef habitats (GED). 
APM 3D FY04 Report characterizing the relationship between alteration of vegetated habitats 
and nekton use of those habitats (AED). 
APM 3F (GPRA # 58) FY04 Preliminary report characterizing relationships between abundance, 
quality, and arrangement of various habitat types and selected biotic assessment endpoints in 
coastal systems (WED). 
APM 5B FY06 Report characterizing relationships between abundance, quality, and arrangement 
of various habitat types and selected biotic assessment endpoints in coastal systems (WED, AED, 
GED, MED). 
APM 6C FY08 Synthesized quantitative species-habitat relationships suitable for developing 
regional habitat-based biocriteria for shorelines, lakes, and estuaries (AED, GED, MED, WED). 
23 
