HR: 15:45h
AN: NB14B-02    [Abstracts]
TI: Do Upstream Lakes Affect the Quantity and Absorbance of Dissolved Organic Matter in Streams?
AU: * Larson, J H
EM: jlarson1@nd.edu
AF: Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556 United States
AU: Frost, P C
EM: pfrost@nd.edu
AF: Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556 United States
AU: Zheng, Z
EM: Zhiyu.Zheng@sdstate.edu
AF: Center for Biocomplexity Studies, South Dakota State University, Brookings, SD 57007 United States
AU: Johnston, C
EM: Carol.Johnston@sdstate.edu
AF: Center for Biocomplexity Studies, South Dakota State University, Brookings, SD 57007 United States
AU: Lamberti, G A
EM: Gary.A.Lamberti.1@nd.edu
AF: Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556 United States
AU: Lodge, D M
EM: David.M.Lodge.1@nd.edu
AF: Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556 United States
AU: Bridgham, S D
EM: bridgham@uoregon.edu
AF: Center for Ecology and Evolutionary Biology and Environmental Studies Program, University of Oregon, Eugene, OR 97403 United States
AB: We hypothesized that the presence of upstream lakes would affect dissolved organic matter (DOM) quantity and absorbance in streams from northern Michigan (USA). We sampled DOM concentration and UV absorbance in 21 streams flowing out of lakes and in 19 streams without upstream lakes during May and August, 2004. We also determined watershed land cover and morphology to assess whether other landscape variables accounted for DOM differences between the two stream types. The concentration of DOM, its UVB absorbance (280-330 nm), and its UVB molar absorbtivity were all significantly lower in lake-outflow streams than in streams without upstream lakes. From the landscape characterization, we found that stream DOM concentration and chemistry were also strongly related to the proportion of wetlands among watershed. However, the strength of the relationships between DOM properties and wetlands differed between stream categories and sampling dates. Long water residence times of lakes appears to lead to lower quantity and greater transparency of DOM moving into streams of this region. The presence of upstream lakes thus represents an additional landscape factor that warrants consideration in future studies of the control of DOM concentration and chemistry in stream ecosystems.
DE: 0400 Biogeosciences
DE: 1806 Chemistry of fresh water
DE: 1845 Limnology
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly