December, 1992.Includes bibliographical references (pages 13-14).This study examined uptake and transfer of heavy metals form benthic invertebrates to brown trout in the Arkansas River. Metals in water, aufwuchs, benthic invertebrates, and fish were measured at stations upstream and downstream from California Gulch (GC). Aufwuchs and benthic invertebrates were highly contaminated by heavy metals downstream from California Gulch. The diet of brown trout at the Arkansas River was dominated by benthic invertebrates. These accounted for 40 to 95 percent of the diet of the brown trout. Differences in prey availability between upstream and downstream resulted in the differences. Ephemeroptera comprised a greater portion of the diet of the fish collected upstream from GC, whereas metal-tolerant organisms were more common in the diet of fish from downstream. Elevated metal levels in water and invertebrates downstream resulted in increased metals in gill and gut tissue; however, metal concentrations in brown trout liver and kidney tissue were generally similar both upstream and downstream. The data suggest that fish regulated metal accumulation. The implications of these findings for the recovery of brown trout populations at the Arkansas River are discussed.Grant no. 14-08-0001-2008, Project no. 10; financed in part by the U.S. Dept. of the Interior, Geological Survey, through the Colorado Water Resources Research Institute
