Monday, May 26, 2008 - 10:45 AM
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Impacts of urbanization and intermittent flow on macroinvertebrates in headwater streams

Hannah R. Lubbers1, Allison H. Roy2, Micheal C. Miller3, Phoebe Richgels3, and Corey Gargano3. (1) Department of Biological Sciences, University of Cincinnati, PO Box 210006, Cincinnati, OH 45221-0006, (2) Office of Research and Development, US Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH 45268, (3) Biological Sciences, University of Cincinnati, PO Box 210006, Cincinnati, OH 45221-0006

Recent Supreme Court cases have brought increased attention to the contribution of intermittent waters to the health of downstream ecosystems. However, there is still limited knowledge on what factors are influencing these frequently disturbed intermittent stream communities. The objective of this study was to determine how urbanization interacts with hydrology to shape headwater stream macroinvertebrate assemblages in Southwest Ohio. During spring (high flows) and summer (low flows) of 2007, we examined both intermittent and perennial reaches in ten streams along a gradient of watershed urbanization (range: 9 – 97% urban land cover). Spring macroinvertebrate richness ranged from 2-14 genera (Chironomidae to family) among all reaches and was similar between perennial and intermittent reaches (df = 9, t = -1.27, p = 0.24). Similarities between perennial and intermittent assemblages indicate that insects have life history traits enabling survival during dry conditions and/or the ability to recolonize intermittent streams once flow resumes. Percentage of urban land cover in the watershed was negatively related to EPT richness (r2 = 0.68, p< 0.001). Our results suggest that catchment urbanization and associated stressors are important drivers of macroinvertebrate assemblages, and seasonal drying is not the sole factor influencing headwater streams.


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