POSTER PRESENTER: http://tinyurl.com/2024WSC-Dean CO-AUTHOR: Julie Beston, UW-Stout TITLE: Beaver dam impacts on water quality, trout populations, and biodiversity: Challenges and early evidence ABSTRACT: As ecosystem engineers, North American beavers (Castor canadensis) have the capacity to affect both abiotic and biotic characteristics of stream and riparian habitats. In western Wisconsin, beavers are often assumed to be pests that negatively affect trout populations. However, there is little direct evidence supporting this position, and blanket beaver removal policies ignore the potential benefits of beavers, both for trout and for the riparian systems in which they live. We are investigating beaver impacts on Class II and III trout streams in western Wisconsin to better elucidate the actual costs and benefits of beaver activity. Preliminary data indicate that water downstream of beaver complexes had lower total inorganic nitrogen and lower chloride than control sites, but the total phosphorus and total suspended sediment were higher. The average water temperature at beaver-impounded sites was also higher than at control sites. Avian species richness observed during brief recording windows was 160% higher at beaver impounded sites on average. Our pilot work also illustrated the technical and logistical limitations to traditional in-stream trout sampling techniques in beaver-impounded locations. We have identified several goals for the next field season: use noninvasive DNA sampling for trout; expand biodiversity sampling using remote recording units calibrated for avian, amphibian, and bat vocalizations and additional in-person surveys; conduct formal wetland plant surveys; and monitor riparian habitat use by mammals. In the second year, we will expand our study to additional beaver-impounded trout streams on private land identified through community outreach. BIO: Cortney Dean is a conservation biology graduate student. She obtained her bachelor’s degree in ecology, evolution, and behavioral biology from Beloit College in 2001. Her prior career was clinical cancer diagnostics, but her current focus is process-based wetland-floodplain restoration and how beavers impact biodiversity and ecosystem services. She is also a gardener, winemaker, and avid maker.