HR: 1340h
AN: H43C-0515    [Abstracts]
TI: Assessing the Effects of High Streamflow on the New Zealand Mudsnail, Boulder Creek, Colorado
AU: * Wynne, K K
EM: kristina.wynne@colorado.edu
AF: Department of Geography, University of Colorado, UCB 260, Boulder, CO 80309 United States
AU: Pitlick, J
EM: pitlick@colorado.edu
AF: Department of Geography, University of Colorado, UCB 260, Boulder, CO 80309 United States
AU: Lewis, W M
EM: william.lewis@colorado.edu
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, UCB 216, Boulder, CO 80309 United States
AU: Anderson, S
EM: suzanne.anderson@colorado.edu
AF: Institute for Arctic and Alpine Research, University of Colorado, UCB 450, Boulder, CO 80309 United States
AB: The effects of hydrologic and geomorphic perturbations on aquatic ecosystems are of great concern as questions pertaining to ecosystem health and invasive species remain unanswered. Of particular interest in the American West is the introduction and spread of the New Zealand Mudsnail, an invasive organism that was confirmed in Colorado in November of 2004. Previous studies of the New Zealand Mudsnail, in streams in the northern Rocky Mountains have provided some insight to their distribution and habitat preferences, yet the link to geomorphology has remained largely unstudied. This study investigates the relationship between high streamflows and the density of the New Zealand Mudsnail in Boulder Creek, CO. Five study sites representing areas both with and without snails were selected in an approximately 10 kilometer reach of Boulder Creek. Field measurements were conducted in the summer of 2005 to gain information pertaining to sediment size, channel geometry and discharge and are used to assess spatial differences in flow. Flow modeling will also be conducted to obtain a high resolution view of bed topography, boundary shear stress and sediment transport. The modeled flow velocities will be used to determine whether New Zealand Mudsnail population densities are significantly affected by variations in sediment transport, intensity and substrate disturbance. Additionally, snail collections were done prior to, during and following peak flow in order to assess longitudinal changes in population densities as well as habitat preferences within study reaches. Preliminary results indicate that the New Zealand Mudsnail population in the selected study reaches of Boulder Creek display habitat preferences, both for the size of sediment to which they attach and for the location of that sediment within the channel. These habitat preferences are hypothesized to be correlated with lateral shear stress variations in the channel. Before peak flows, the snails were found throughout the width of the channel. Following extended near-bankful flows which moved the majority of the sediment on the bed, snails displayed preference for more stable habitat, particularly that sediment located on the sides of the channel. The preliminary examination of the data suggests that the channel forming flows did not, however, contribute significantly to the downstream movement of the snails in the study reach.
DE: 1813 Eco-hydrology
DE: 1825 Geomorphology: fluvial (1625)
DE: 1860 Streamflow
DE: 1862 Sediment transport (4558)
SC: Hydrology [H]
MN: Fall Meeting 2005