Ecological Considerations for Planning and Designing Bridges ROAD INFRASTRUCTURE AND STREAM HABITAT CONNECTIVITY: RESEARCH TO AID MANAGEMENT AND CONSERVATION PLANS IN A CHANGING ENVIRONMENT

Poorly-designed road-stream crossings can put both ecosystems and transportation infrastructure at risk. In response to these threats, an interdisciplinary team, using the Connecticut River basin in the northeastern US as a focus area, but extending throughout the northeast and north-central US, is currently investigating two major research questions: 1) What are the demographic and genetic consequences of road-associated fragmentation for stream fish populations, and can genetic surveys and population models be used to assess fragmentation and connectivity? 2) Are crossings that are likely to be barriers to fish passage have a higher probability of structural failure under current and predicted future climate conditions? Our results to date indicate that fragmentation associated with barriers can strongly influence both local and watershed-scale probabilities of extinction for wild brook trout populations, and have potential impacts on the value of recreational fisheries via changes in population size structure. In addition preliminary results indicate that undersized culverts are more likely to be barriers to passage. The results of our current and future work will be used to inform conservation planning and culvert replacement strategies on both federal and non-federal lands, and to assess the success of these efforts in restoring population connectivity and contribute to sustainability of key species and ecosystem services.