BEAVER-INDUCED BIOGEOCHEMICAL ALTERATIONS IN MOUNTAIN STREAMS
Beavers (Castor canadensis) are integral components of many alluvial stream ecosystems. Beavers cut wood and build dams, which decreases stream energy and causes the water column to drop fine sediment upstream of the dam. Accumulation of sediment, increased water residence time and hyporheic exchange alter stream biogeochemistry within ponds, compared to downstream reaches. This research aims to understand how maintained and unmaintained beaver dams alter the flux of nutrients in mountain stream ecosystems. Water and sediment samples were collected from a stream with beaver dams (n=4) and a stream with abandoned beaver dams (n=3) in Logan Canyon, UT. Results suggest an increase in pH (p < 0.01), dissolved oxygen, temperature, conductivity and dissolved organic carbon (p < 0.05) in maintained beaver ponds as compared to downstream reaches. The stream with maintained beaver dams differed significantly from the stream with unmaintained beaver dams with respect to longitudinal temperature, pH, dissolved oxygen and chlorophyll-a. Breached dams exhibited little effect on most biogeochemical parameters tested, and measurements at the most upstream site differed insignificantly from the furthest downstream site. Results from this study suggest that maintained beaver dams strongly influence stream biogeochemistry.
Deni Murray (Primary Presenter/Author), Utah State University, Department of Watershed Sciences and the Ecology Center, firstname.lastname@example.org;