HR: 09:00h
AN: B51A-03    [Abstracts]
TI: Effects of Spatial Variability in Flow and Sediment Transport on Benthic Invertebrates During Runoff Events: Patch and Reach-Scale Challenges
AU: * Kenworthy, S
EM: stephen.kenworthy@wku.edu
AF: Department of Geography and Geology, Western Kentucky University, 1 Big Red Way, Bowling Green, KY 42101 United States
AB: The short-term impact of streamflow increases on benthic populations depends on spatial patterns of organism dispersal and mortality that are difficult to observe and quantify in the field. Laboratory and field experiments suggest that the size distribution, structure, and stability of streambed sediment play critical roles in mediating the effects of flow increases on dispersal and mortality of organisms. I present the results of laboratory flume experiments in which flow and sediment transport were progressively increased and the resulting displacement of aquatic insect larvae was quantified. These and other experiments demonstrate that the displacement and mortality of benthic organisms scales with streambed entrainment and sediment transport, but that bed structure and the physical and behavioral traits of the biota can strongly influence this relationship. Application of these patch-scale experimental results to understanding the hydrogeomorphic determinants of reach-scale flood impacts involves important scientific challenges and uncertainties. Reliable estimation of the spatial variability of streambed mobilization and sediment transport as a function of channel and substrate characteristics, flow history and sediment supply is necessary to compare the effects of different events or among different stream reaches. Also needed is a better appreciation of the spatial scales of organism dispersal during flow events and the physical and biological controls on patterns of dispersal at various scales.
DE: 1815 Erosion and sedimentation
DE: 1821 Floods
DE: 1824 Geomorphology (1625)
DE: 1845 Limnology
SC: Biogeosciences [B]
MN: 2005 Joint Assembly