Date Awarded


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)


Virginia Institute of Marine Science


Carlton Hershner, Jr


This dissertation addresses the need to define potential impacts of recent and proposed changes in federal wetland regulation in a quantifiable manner. Consideration was made not only of total wetland acreage and wetland types that could sustain losses, but also to categorize the effect such losses would have in terms of wetland functions, at the watershed scale. This work took a Geographic Information Systems (GIS) approach, and included employing a best-professional judgment model for scoring habitat, water quality and flood attenuation functions to determine potential cumulative impacts; a water quality study which related wetland and watershed variables to nutrient and sediment loads; and an amphibian metapopulation model to determine the effects of loss of landscape connectivity resulting from wetland management decisions. The study area encompassed several watersheds in Southern Virginia, USA. Results from best professional judgment model show that despite a decrease over the years in acreage receiving reduced regulatory protection, the functional caliber of wetlands afforded the least protection is actually higher with each new implementation of regulatory criteria. These results, and the results of similar models, updated as more information and data sets become available, should be a valuable tool for both regulators and managers at local, as well as regional and The water quality model reduced 41 wetland and watershed variables to 5 principal components, which were then used in regression equations to relate the variables to nutrient and sediment loads. Although differing variables played roles in different water quality components, the overriding factor affecting improved water quality related to the proportion of vegetated area found within a 100 meters of stream courses, with negative water quality related to the proportion of developed to vegetated areas within the 100 meter buffer. Results from the amphibian habitat model highlight the importance of the pattern of wetlands across the landscape. Removal of wetlands smaller than 0.5 acres had a greater influence on occupancy rates in all wetlands, presumably due to their position providing between wetland connectivity. Policy and management decisions should be altered to consider each of these conclusions if functional conservation is to be achieved.



© The Author