HR: 1330h
AN: NB33E-07    [Abstracts]
TI: Dominant Discharge Analysis of Ecological Processes in Streams
AU: * Doyle, M W
EM: mwdoyle@email.unc.edu
AF: Department of Geography University of North Carolina, CB #3220, Chapel Hill, NC 27599-3220 United States
AU: Stanley, E H
EM: ehstanley@wisc.edu
AF: Center for Limnology University of Wisconsin, 680 North Park Street, Madison, WI 53760 United States
AU: Strayer, D L
EM: strayerd@ecostudies.org
AF: Institute of Ecosystem Studies, PO Box AB (65 Sharon Turnpike), Millbrook, NY 12545 United States
AU: Jacobson, R B
EM: Robb_jacobson@usgs.gov
AF: USGS-CERC, 4200 New Haven Road, Columbia, MO 65201 United States
AU: Schmidt, J C
EM: jschmidt@cnr.usu.edu
AF: Department of Aquatic, Watershed, and Earth Resources, Utah State University, Logan, UT 84322-5210 United States
AU: Fuller, R
EM: rfuller@mail.colgate.edu
AF: Department of Biology, Colgate University, Hamilton, NY 13346 United States
AU: Manners, R
EM: manners@email.unc.edu
AF: Department of Geography University of North Carolina, CB #3220, Chapel Hill, NC 27599-3220 United States
AU: Small, M J
EM: mjsmall@email.unc.edu
AF: Department of Geography University of North Carolina, CB #3220, Chapel Hill, NC 27599-3220 United States
AB: Here we apply the concept of "dominant discharge" from fluvial geomorphology to analyze the influence of flow regime on stream ecology. Quantitative metrics of effective discharge (Qeff) and functionally-equivalent discharge (Qfed) were developed to quantify how discharge drives organic matter transport, algal growth, nutrient retention, macroinvertebrate disturbance, and habitat availability. We quantify the magnitude of discharge at which a variable of interest is maximized over the range of discharges experienced by the stream (Qeff), and the single discharge that recreates the long-term average condition of the variable (Qfed) using a meta-analysis of published studies and modeling. Results suggest that a range of discharges are important for different ecological processes in an individual stream. All discharges are not equally important; instead, clusters of dominant discharge values exist that correspond to near modal flows and moderate floods for the 5 variable sets examined. We suggest four types of ecological response to discharge variability: discharge as a transport mechanism, a regulator of habitat, a process-modulator, and as a disturbance. Dominant discharge analysis will perform well when there is a unique, essentially instantaneous relationship between discharge and an ecological process, and poorly when effects of discharge are delayed or confounded by legacy effects.
DE: 0400 Biogeosciences
DE: 1625 Geomorphology and weathering (1824, 1886)
DE: 1845 Limnology
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly