Tuesday, June 5, 2007
435

The Effect of Agro-Urban Land-Use on Stream Retention of Dissolved Nitrogen, Carbon, and Phosphorus in SE Idaho

Heather A. Bechtold1, Amy M. Marcarelli1, Colden V. Baxter2, and Richard S. Inouye1. (1) Center for Ecological Research and Education, and Department of Biological Sciences, Idaho State University, Campus Box 8007, Pocatello, ID 83201, (2) Stream Ecology Center and Biological Sciences, Idaho State University, Campus Box 8007, Pocatello, ID 83201

Human land-use change is a primary cause of increased nutrient export and eutrophication in streams. Understanding how land-use alters a stream’s ability to retain or uptake nutrients may aid in understanding nutrient export (N, P, C) to downstream aquatic ecosystems. We examined the effect of land-use on nutrient uptake, using nutrient spiraling techniques, in two tributaries of the Portneuf River, southeast Idaho. Mink Creek is more heavily impacted by agriculture and urbanization, while Gibson Jack is protected as a former municipal water source. Multiple-concentration, short term releases of nitrogen (NaNO3), phosphorus (KH2PO4), and organic carbon (C6H12O6) were conducted in 2006 and used to estimate ambient uptake length (Sw), uptake velocity, and uptake rate. Ambient uptake lengths for both N and C in Mink Creek were considerably greater than ambient uptake lengths in Gibson Jack. Expansion of this study to include other impacted and un-impacted tributary streams is planned and will be conducted seasonally to include times of peak autotrophic activity, such as summer, when nutrient uptake rates may be more dramatically impacted by the consequences of land use.