Wednesday, June 6, 2007 - 2:00 PM
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The Trouble with Relationships: Influence of Spatial Scale on Wetland Macroinvertebrate Community Response to Environmental Stressors

Mollie D. McIntosh1, Richard W. Merritt1, Vanessa L. Lougheed2, M. Eric Benbow1, and R. Jan Stevenson3. (1) Entomology, Michigan State University, East Lansing, MI 48824, (2) Biological Sciences, University of Texas at El Paso, 500 W. University Ave., El Paso, TX 79968, (3) Zoology, Michigan State University, East Lansing, MI 48824

Wetlands provide many functions, both ecological and economical; however, they are continuously threatened by numerous human activities. These activities (e.g., agriculture, development) subsequently generate environmental stressors (e.g., nutrients, road salt) that can impact the physical, chemical and biological integrity of wetland ecosystems. It is hypothesized that macroinvertebrate communities will vary with the presence and intensity of an environmental stressor; however, identifying these relationships can be difficult due to complex interactions among multiple human activities and stressors and wetland type and size. In an effort to reduce this complexity, we identified potential relationships between macroinvertebrate communities and environmental stressors at three spatial scales: the ecosystem level (marsh wetlands), class level (riverine, palustrine, and lacustrine) and habitat level (emergent, submergent vegetation). During the summer of 2002 and 2003, macroinvertebrates were collected from 64 inland marshes within the Muskegon River Watershed (Michigan, USA). Relationships between macroinvertebrate metrics and environmental stressors showed spatially explicit variation among scales. Further, stressor-specific metrics were found to change between scales of measurement. Results from this multi-scale analysis will allow for the identification of more useful indicators of wetland health that provide a guideline for scale-defined wetland bioassessments.