test of watershed classification systems for ecological risk assessment

• Published in: Environmental toxicology and chemistry Vol. 19; no. 4; pp. 1174 - 1181
• Main Authors: Detenbeck, Naomi E., Batterman, Sharon L., Brady, Valerie J., Brazner, John C., Snarski, Virginia M., Taylor, Debra L., Thompson, Jo A., Arthur, John W.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Hoboken Wiley Periodicals, Inc 01.01.2000; SETAC
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Classification; Conservation, protection and management of environment and wildlife; Environmental degradation: ecosystems survey and restoration; Freshwater; Fundamental and applied biological sciences. Psychology; Hydrology; Lake; North America, Superior L; Risk assessment; Superior; Watersheds; Lake Superior; Great Lakes of America; North America; America; Vulnerability; Risk analysis; Environmental management; Freshwater environment; Hydrology; Hydrobiology; Ecosystem; Watershed; Classification; Water quality; Lakes; Environmental monitoring; Wetland
• ISSN: 0730-7268; 1552-8618
• DOI: 10.1002/etc.5620190451

To facilitate extrapolation among watersheds, ecological risk assessments should be based on a model of underlying factors influencing watershed response, particularly vulnerability. We propose a conceptual model of landscape vulnerability to serve as a basis for watershed classification systems to predict resistance and resilience of aquatic ecosystems to hydrology-related stressors. Watershed area, storage capacity, channel slope, and soil permeability determine sensitivity of lotic systems to stressors associated with land-use activities that impact hydrologic regimes. Natural hydrologic disturbance regimes also influence the resilience of aquatic systems by selecting for life history strategies associated with rapid recolonization following disturbance. Variability in some of these physiographic driving factors can be partitioned by landscape classification schemes such as the U.S. Forest Service Ecological Unit Classification System, while others (watershed storage) may explain remaining variability within landscape units. We are conducting a comparative watershed study to examine simple and interactive effects of physiographic units, watershed storage (lakes + wetlands), and land-clearing activities in watersheds surrounding the western arm of Lake Superior. Initial results for second-order watersheds indicate significant watershed class effects on baseflow water quality, percent motile biraphid diatom species in periphyton communities, habitat quality, and fish community integrity. Future studies have been designed to examine cumulative effects downstream.