HR: 09:45h
AN: NB41C-06    [Abstracts]
TI: Nutrient Uptake in Mountain Lake Outflow Streams: Evidence for the Importance of Inflow Hydrodynamics and In-Lake Processes
AU: * Burkart, G
EM: greta@cc.usu.edu
AF: Department of Aquatic, Watershed and Earth Resources / Ecology Center, Utah State University, Logan, UT 84322 United States
AU: Wurtsbaugh, W
EM: wurts@cc.usu.edu
AF: Department of Aquatic, Watershed and Earth Resources / Ecology Center, Utah State University, Logan, UT 84322 United States
AU: Fleenor, W
EM: wefleenor@ucdavis.edu
AF: Department of Civil and Environmental Engineering, University of California-Davis, Davis, CA 95616 United States
AU: Luecke, C
EM: luecke@cc.usu.edu
AF: Department of Aquatic, Watershed and Earth Resources / Ecology Center, Utah State University, Logan, UT 84322 United States
AB: In oligotrophic, high mountain lakes, cold plunging inflows may send nutrients directly to deep chlorophyll layers in the metalimnia. Compared to surface inflows, plunging inflows create a larger mixing volume for inflowing water and may allow phytoplankton in deep chlorophyll layers to take up nutrients before they can be exported from the lake. We hypothesized that inflow hydrodynamics interact with biological processes to influence availability of nutrients to primary producers in the outflow. We added water-mass (bromide) and biologically active (¹⁵N-ammonia) tracers to two oligotrophic, high mountain lakes via either a plunging stream water inflow or a surface addition. The average hydraulic residence time was three-times higher following the plunging inflow addition, compared to the surface addition. The nutrient retention index, however, was an order of magnitude higher, suggesting the interaction between inflow hydrodynamics and biological processes leads to a greater effect on nutrient export than on hydrologic export. Thus, if inflow streams are warm and mix directly into the epilimnion (as in our surface addition) nutrients will pass through the system faster and be more readily available to primary producers in outflow streams.
DE: 9901 NABS Student Award - Basic Research
DE: 9903 NABS Student Award Methodology
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly