HR: 1330h
AN: B33E-09 [Abstracts]
TI: Abiotic Factors Affecting Benthic Invertebrate Biomass and Community Structure in a Fourth-Order Rocky Mountain Watershed
AU: * Chanat, J G
EM: jgc3n@virginia.edu
AF: Department of Environmental Sciences, University of Virginia, P.O. Box 400123, Charlottesville, VA
22903 United States
AU: Clements, W H
EM: willc@cnr.colostate.edu
AF: Department of Fishery and Wildlife Biology, College of Natural Resources, Colorado State University,
Fort Collins, CO 80523 United States
AU: MacDonald, L H
EM: leemac@cnr.colostate.edu
AF: Department of Forest, Rangeland, and Watershed Stewardship, College of Natural Resources, Colorado State University, Fort Collins, CO 80523 United States
AB:
The potential ecological impact of excess streambed sediment resulting from forest management activities is a persistent
concern for land managers. This study examined the relationship between streambed sediment, along with other site- and
reach-scale abiotic factors, and benthic macroinvertebrate community structure in a 272 km2 basin in the Colorado Front
Range. Physical habitat parameters and invertebrates were sampled in late summer at 68 sites located in sixteen stream
reaches. Invertebrate data were used to formulate twenty indices of community structure. Multiple regression identified
site-level substrate particle size as the most important predictor of six indices, including total density (R2 = 0.22),
biomass (R2 = 0.17), and taxa richness (R2 = 0.32). All of the remaining fourteen indices were most strongly
predicted by reach-level variables, including discharge (percent shredders, R2 = 0.24; Plecoptera density, R2 =
0.29), and elevation (percent collector-filterers, R2 = 0.28; Trichoptera density, R2 = 0.37). Although the sites
represented a wide range of substrate composition and embeddedness, no physical variable associated with fine sediment
appeared as a strong predictor of any of the twenty indices. Thus, sediment is not among the most important factors
associated with site-to-site variability of benthic community structure in this relatively pristine watershed.
DE: 1803 Anthropogenic effects
DE: 1845 Limnology
SC: Biogeosciences [B]
MN: 2005 Joint Assembly