Thursday, May 29, 2008 - 10:45 AM
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Use of bioaccumulated metal in tolerant, resident taxa to indicate ecotoxicological effects on stream macroinvertebrate assemblages

Daniel Cain1, Samuel Luoma2, and Philip Rainbow2. (1) U.S. Geological Survey, 345 Middlefield Road, MS 465, Menlo Park, CA 94025, (2) Department of Zoology, The Natural History Museum, London, United Kingdom

Ecological risk assessments for metals can use tissue concentrations in resident taxa to assess bioavailable metal exposures and assemblage structural metrics to assess community-level effects.  However, if sensitive taxa are absent where contamination is greatest, consistent determination of exposure is problematic.  Therefore, use of widespread and metal tolerant taxa is necessary for consistent monitoring of exposure. These taxa are most useful if bioaccumulated metal concentrations are “calibrated” against changes in relevant community metrics.  We analyzed copper (Cu) bioaccumulation in the tolerant caddisfly, Hydropsyche, in relation to community-level effects indicators (richness, EPT richness, mayfly richness and abundance) in the Clark Fork River, USA where Cu contamination has impaired aquatic communities.  Dissolved Cu and bioaccumulated Cu (in Hydropsyche) correlated negatively with metal-sensitive metrics (mayfly richness and abundance of heptageniid mayflies).  The distribution in metrics values decreased with increasing bioaccumulated Cu, indicating the increasing influence of Cu relative to other potential limiting factors.  Least squares and quantile regressions described the responses of metrics to bioaccumulated Cu, suggesting the feasibility of using bioaccumulated metal in tolerant taxa for detecting the ecological effects of metal contamination.


Web Page: metals, bioaccumulation, biomonitor