ScholarWorks at University of Montana

Trait characteristics as determinants of metal exposure and uptake for stream invertebrates in the Clark Fork River, MT

Relations between whole-body metal concentrations and species traits were examined for 40 invertebrate taxa in the middle and upper reaches of the Clark Fork River drainage to determine 1) the extent to which trait-based characteristics accounted for species-specific differences in metal exposure and uptake, and 2) which traits were most effective in identifying exposure pathways and predicting uptake potential. Traits represent the functional attributes of a species and include morphological, physiological, behavioral, and ecological characteristics. Traits related to developmental strategies (e.g., generations per year) and habitat use (e.g., fluvial and substrate preferences) generally were poor predictors of metal bioaccumulation. In contrast, metal uptake was positively related to traits characterizing chemical and physical stressor tolerances. Comparison of feeding trait affinities and metal bioaccumulation patterns showed that feeding behavior was the strongest predictor of metal uptake among the traits examined. Metal concentrations increased in taxa relying on filtering (feeding on suspended particulate organic matter) or gathering (feeding on deposited particulate organic matter) as part (>40%) of their food acquisition strategy. In contrast, concentrations decreased as predation assumed a greater proportion of overall feeding activity. Application of trait characteristics as predictive tools may help identify taxa that may be at greatest risk in metal-disturbed environments and, accordingly, the most sensitive indicators of ecosystem recovery following remediation.