HR: 15:30h
AN: NB14B-01    [Abstracts]
TI: The effect of land use on DOC and DON uptake in headwater streams in the Kalamazoo River basin, Michigan
AU: * Taylor, L C
EM: ltaylor4@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556 United States
AU: Tank, J L
EM: jtank@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, Notre Dame, IN 46556 United States
AB: Research on the effect of land use on stream ecosystems has largely focused on impacts of elevated inorganic nutrients such as nitrogen. However, anthropogenic activities can potentially alter the dynamics of dissolved organic carbon (DOC) and nitrogen (DON). We selected 18 streams draining 6 land-use types: forested, urban, distal urban, agriculture, distal agriculture, and buffered agriculture. We conducted seasonal short-term nutrient releases of acetate (representing labile DOC) and glycine (representing labile DON), and compared them with short-term releases of inorganic N (NH₄⁺). We predicted that the increase in inorganic nitrogen associated with land use would lead to increased DOC uptake and decreased demand for DON. Preliminary results indicate that demand for DOC (as uptake velocity) was highest in the urban stream during both autumn and spring. Uptake velocity of NH₄⁺ was variable in all streams in autumn and highest in the agricultural stream in spring. In fall, DOC uptake velocity was generally higher than for NH₄⁺, but this pattern was not seen in spring. DOC uptake velocity increased with an increase in water-column NH₄⁺ (r²=0.387, p=0.041) indicating that elevated inorganic N concentrations associated with land use can potentially increase DOC uptake, further altering stream nutrient processing and export.
DE: 1803 Anthropogenic effects
DE: 1806 Chemistry of fresh water
DE: 1899 General or miscellaneous
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly