Biogeochemical data from the Clark Fork River, Montana, provide the basis for site-specific predictions of Cu and Cd concentrations in two species of caddisflies (Fig 3).

Dissolved concentrations, [M]w, are based on seasonal (May-August) averages and coincide with the life-history of the caddisfly larvae; dietary exposure, [M]f, was determined by analyzing metal concentrations in caddisfly foreguts, a proxy for dietary exposure (see methods for more detail). Species do not always co-occur at each site (--).