Associations of benthic macroinvertebrate assemblages with environmental variables in the upper Clear Creek watershed, California

Western North American Naturalist
By: , and 



Benthic macroinvertebrates are integral components of stream ecosystems and are often used to assess the ecological integrity of streams. We sampled streams in the upper Clear Creek drainage in the Klamath—Siskiyou Ecoregion of northwestern California in fall 2004 (17 sites) and 2005 (original 17 plus 4 new sites) with the objectives of documenting the benthic macroinvertebrate assemblages supported by the streams in the area, determining how those assemblages respond to environmental variables, assessing the biological condition of the streams using a benthic index of biotic integrity (IBI), and understanding the assemblages in the context of biodiversity of the ecoregion. We collected both reach-wide (RW) and targeted-riffle (TR) macroinvertebrate samples at each site. The macroinvertebrate assemblages were diverse, with over 150 genera collected for each sampling protocol. The macroinvertebrate assemblages appeared to be most responsive to a general habitat gradient based on stream size, gradient, flow, and dominance of riffles. A second important habitat gradient was based on elevation and dominance of riffles. A gradient in water quality based on concentrations of dissolved ions and metals was also important. Models based on these 3 gradients had Spearman's rank correlations with macroinvertebrate taxonomic composition of 0.60 and 0.50 for the TR and RW samples, respectively. The majority (>50%) of the sites were in good or very good biological condition based on IBI scores. The diversity of macroinvertebrate assemblages is associated with the diversity of habitats available in the Klamath—Siskiyou Ecoregion. Maintaining the aquatic habitats in good condition is important in itself but is also vital to maintaining biodiversity in this diverse and unique ecoregion.

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Publication type Article
Publication Subtype Journal Article
Title Associations of benthic macroinvertebrate assemblages with environmental variables in the upper Clear Creek watershed, California
Series title Western North American Naturalist
DOI 10.3398/064.072.0406
Volume 72
Issue 4
Year Published 2012
Language English
Publisher Monte L. Bean Life Science Museum, Brigham Young University
Contributing office(s) California Water Science Center
Description 22 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Western North American Naturalist
First page 473
Last page 494
Country United States
State California
Other Geospatial Upper Clear Creek Watershed
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