wetlands is quite limited. Although watershed fragmentation has been shown to be related to the 
structure and function of biotic assemblages in streams from Western Lake Superior (Detenbeck 
et al. 2000), fragmentation effects on habitat condition and biota associated with Great Lakes 
coastal wetlands have not been well documented. We suspect that this sort of fragmentation- 
induced habitat alteration also will cause changes in higher tropic levels in Great Lakes coastal 
wetlands. 
Some of our endpoints for testing this idea may be yellow perch and northern pike population 
abundances, and overall fish biodiversity at river-influenced coastal wetlands having differences 
in fragmentation levels in their watersheds. GIS characterization, statistical analysis, and model 
development sequences will parallel those planned for stream watersheds in the Pacific 
Northwest. We plan to refine our definition of fragmentation to incorporate a variety of land-use 
types by using a "land-use equivalency** approach which will allow us to place our wetland sites 
along a vulnerability gradioit, and provide a better opportunity to link watershed land-use to 
habitat and fish response curves for Great Lakes coastal wetlands. Collaborations with 
researchers from other institutions will allow us to increase the number of sites where fish data 
will be available and expand the vulnerability gradient to include much of the Great Lakes that 
would not otherwise have been possible. 
Because we think the response to watershed fragmentation by wetland fishes will vary with 
wetland type, we will need to test whether a wetland classification system effectively groups 
coastal wetlands into similar response classes. Although there is a presumption that coastal 
wetland hydro geomorphology influences biota, there is little direct supporting evidence. It is 
well known, however, that aquatic community structure of higher tropic levels is influenced by 
vegetation structure in coastal wetlands, and vegetation stmcture appears to be related to 
hydrogeomorphology. So, it seems likely that our fish response variables (population and 
assemblage level) also will be related to differences in wetland hydrogeomorphology. After 
assessing whether this is the case at different coastal wetland types (e.g., open estuary, barred 
estuary, barrier beach lagoons, open coastal), we will be better able to extrapolate the 
significance of our fragmentation results on a region-wide basis by knowing the distribution of 
wetland types across the landscape and the fragmentation levels in their watersheds. 
Effects of Network Structure and Connectivity on Fish Movement 
Because fish are mobile, they are not limited to nor exclusively influenced by the habitat quality 
of a single stream reach. Rather, they move between reaches and may require different habitat 
conditions during different life stages. The spatial distribution of habitat condition and the 
ability of fish to move between reaches are therefore important considerations. For example, 
salmonids returning from the ocean attempt to reach the same stream reach in which they were 
spawned. Any obstruction in the stream network, which forces them to expend more energy to 
return, could affect spawning success. If a barrier completely prevented them from returning to a 
particular home reach, then the ability of strays to decolonize new habitat would depend on the 
spatial distribution of habitat near the home reach and the occurrence of other obstructions to 
movement Thus any effort aimed at examining watershed management effects on fish 
populations needs to consider the effect of the watershed on the spatial structure of the network 
(e.g., the distribution of habitat condition) and on the level of connectivity among stream reaches. 
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