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A Comparison of the Impacts of Culverts Versus Bridges on Stream Habitat and Aquatic Fauna (2004-08)

Principal Investigator(s): Dr. Jay F. Levine, Associate Professor
    Department of Epidemiology and Public Health, NCSU College of Veterinary Medicine
Dr. W. Gregory Cope, Associate Professor
    Department of Environmental & Molecular Toxicology, North Carolina State University
Dr. Arthur E. Bogan, Curator of Aquatic Invertebrates
    Research Laboratory, North Carolina Museum of Natural Sciences
Dr. Damian Shea, Professor
    Department of Environmental & Molecular Toxicology, North Carolina State University
Dr. Dave Eggleston,
    Department of Atmospheric Sciences, North Carolina State University
Dr. James Gregory,
    Department of Forestry, North Carolina State University
Project Period & Status: July, 2003  to  June, 2005   Complete
Topic(s): Wildlife/Terrestrial Ecosystems    
Total Funding:
Abstract: This project was an interdisciplinary look at the differences in impacts between culverts and bridges on stream habitat and stream fauna. There were four essential components:

1. Freshwater mussels: We took habitat measurements and conducted mussel surveys at 43 culverts across the piedmont in NC. Overall, habitat downstream of culverts was much more impacted than downstream of bridges. The reduction in mussel populations downstream of culverts was also more pronounced than at bridge sites. These effects were magnified in certain soil types that were more erodable.

2. Geomorphology: Detailed stream morphology and substrate measurements were taken at arch, pipe and box culverts and bridges. All crossing types were shown to increase stream cross-sectional area downstream by constricting flow at the crossing.

3. Toxicology: We conducted toxicity tests with polycyclic aromatic hydrocarbons (PAHs) on all life stages of freshwater mussels. We also assessed genetic damage due to PAH exposure. We found that PAHs are not acutely toxic to mussels but may possibly be contributing to long-term genetic damage.

4. Fish Passage: Fish community structure and passage was assessed at different crossing designs in the piedmont. There were no significant differences detected in community structure between crossing types. Though not statistically significant, data suggest a trend toward greater fish movement through bridges than culverts.

For more information, visit the NCDOT Research Project 2004-08 website.

Publications & Presentations: 2004-08 Final Report (PDF 10.27 MB)
For More Information:
NC State University - link opens in new window
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