HR: 17:40h
AN: H34A-07    [Abstracts]
TI: Limits on characteristics of invertebrate assemblages associated with streamflow patterns in the western United States
AU: * Konrad, C
EM: ckonrad@tnc.org
AF: US Geological Survey, 934 Broadway, Tacoma, WA 984302, United States
AU: * Konrad, C
EM: ckonrad@tnc.org
AF: The Nature Conservancy, 1917 1st Ave, Seattle, WA 98101, United States
AU: Brasher, A
EM: abrasher@usgs.gov
AF: US Geological Survey, 121 West 200 South, Moab, UT 84532, United States
AU: May, J
EM: jasonmay@usgs.gov
AF: US Geological Survey, Placer Hall 6000 J Street, Sacramento, CA 95819,
AB: River restoration depends on re-establishment of the range of physical and biological processes that comprise the river ecosystem. Streamflow is the definitive physical processes for river ecosystems, so hydrologic alteration represents a potentially significant issue to be addressed by restoration efforts. Given adaptation of lotic species to naturally variable streamflow patterns over evolutionary time scales, however, lotic communities are resilient to at least some forms of hydrologic variability. As a result, river restoration may be successful despite limited but biologically insignificant hydrologic alteration. The responses of benthic invertebrate assemblages to variation in streamflow patterns across the western United States were investigated to identify biologically important forms and magnitudes of hydrologic variability. Biological responses to streamflow patterns were analyzed in terms of ceilings and floors on invertebrate assemblage diversity and structure using a non-parametric screening procedure and quantile regression. Variability at daily and monthly time scales was the most common streamflow pattern associated with broad metrics of invertebrate assemblages including abundance; richness and relative abundance of Ephemeroptera, Plecoptera, Trichoptera and non-insects; dominance; and diversity. Low flow magnitude and annual variability were associated with richness and trophic structure. The frequency, magnitude, and duration of high flows were associated with abundance and richness. Longer term streamflow metrics (calculated over at least 5 years) were more important than recent flows (30 and 100 days prior to invertebrate sampling). The results can be used as general guidance about when hydrologic alteration is likely to be an important factor and what streamflow patterns may need to be re-established for successful river restoration.
DE: 1813 Eco-hydrology
DE: 1860 Streamflow
SC: Hydrology [H]
MN: 2007 Fall Meeting