HR: 1330h
AN: H52A-1151    [PDF]
TI: Linkages Between Hydraulics, Morphology, and Benthic Communities in High-Gradient Streams
AU: * Wilcox, A C
EM: awilcox@cnr.colostate.edu
AF: Department of Geosciences, Colorado State University, Fort Collins, CO 80523
AU: Peckarsky, B L
EM: BLP1@cornell.edu
AF: Department of Entomology, Cornell University, Ithaca, NY 14853
AB: In order to explore the effects of physical processes on benthic communities in mountain stream channels, field surveys of stream hydraulics and channel morphology were completed in fifteen stream reaches in the upper East River basin, Colorado. Biological data on macroinvertebrate abundance, life history, mortality, and drift rates have been collected in these streams as part of a multi-year study of mayfly population dynamics, grazer-algal interactions, and predator-prey interactions. The present study entailed collection of data on channel geometry and gradient, grain sizes, and flow characteristics to provide a basis for examining the role of shear stress, stream power, and other physical variables on ecological processes. The study streams had bed gradients ranging from 0.018 to 0.11 m/m and were mostly characterized by step-pool or step-riffle morphology. Seven reaches with fish and eight fishless reaches were surveyed; presence or absence of fish has been found to strongly affect benthic macroinvertebrate dynamics in the study streams. Streams lacking fish tended to have smaller drainage areas, steeper gradients, greater flow resistance (higher Darcy-Weisbach friction factors), and lower discharges than streams with fish, although boundary shear stresses did not significantly differ in fish versus fishless streams. Darcy-Weisbach friction factor showed a strong negative correlation with discharge in the study streams, reflecting a shift in the balance between driving and resisting forces as stream size decreases.
DE: 1800 HYDROLOGY
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
DE: 1851 Plant ecology
SC: Hydrology [H]
MN: 2003 Fall Meeting