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Research about Clark Fork River

Source-linked reports with geographic coverage including Clark Fork River.

4 recordsLinked to original sources
USGS2019

Application of multistate modeling to estimate salmonid survival and movement in relation to spatial and temporal variation in metal exposure in a large mining-impacted river

We used telemetry and multistate modeling to estimate survival and movement of brown trout Salmo trutta and westslope cutthroat trout Oncorhynchus clarkii lewisi in relation to dissolved copper concentrations in 189 km of the upper Clark Fork River, Montana, a mining-impacted river in western Montana. Annual survival estimates for both brown trout (range, 0.27-0.53) and westslope cutthroat trout (range, 0.001-0.34) over the three-year study were low and variable within the study area, with survival negatively related to level of copper exposure. Survival probability for brown trout and westslope cutthroat trout in the uppermost river segment, where dissolved copper concentrations frequently exceeded acute criteria for aquatic life (range, 31-60 d >13.4 µg·L-1), was 2.1 times and 122 times lower, respectively, compared to survival rates in the lowermost segment that had relatively low dissolved copper (0 d exceedance of acute concentration). Seasonal differences in survival also appeared to be related to copper exposure level. Lowest survival for both species occurred in the spring-summer period when dissolved copper concentrations were elevated coincident with higher discharge. Movement among study segments was generally low, and cutthroat trout in particular showed low movement into the uppermost river segment with the most elevated copper levels. Both species showed high rates of movement into tributaries, which coincided with their respective spawning migrations rather than as an apparent avoidance of elevated copper levels. Our research design provided an uncommon opportunity to directly relate the degree of contaminant exposure to estimates of fish survival and movement at a population-level over a large spatial scale. This linkage between survival rate and level of copper exposure for both brown trout and cutthroat trout in the upper Clark Fork River suggests that additional removal of tailings deposits could improve survival rates.

Montana↗
USGS1994

Toxicity of metal-contaminated sediments from the upper Clark Fork River, Montana, to aquatic invertebrates and fish in laboratory exposures

Sediments of the upper Clark Fork River, from the Butte and Anaconda area to Milltown Reservoir (230 km downstream), are contaminated with As, Cd, Cu, Pb, Mn, and Zn primarily from mining activities. The toxicity of pore water from these sediments was determined using Daphnia magna (48-h exposure), rainbow trout (96-h exposure), and Microtox®. However, pore-water data from these exposures were questionable because of changes in the toxicity of pore-water samples after 5 to 7 d of storage. Whole-sediment tests were conducted with Hyalella azteca (28-d exposure), Chironomus riparius (14-d exposure), rainbow trout ( Oncorhynchus mykiss ) 21- to 28-d exposure and Daphnia magna (2- to 22-d exposure). Sediment samples from Milltown Reservoir and the Clark Fork River were not generally lethal to test organisms. However, both reduced growth and delayed sexual maturation of amphipods were associated with exposure to elevated concentrations of metals in sediments from the reservoir and river. Relative sensitivity (most sensitive to least sensitive) of organisms in whole-sediment toxicity tests was: Hyalella azteca > Chironomus riparius > rainbow trout > Daphnia magna . Relative sensitivity (most sensitive to least sensitive) of the three end points evaluated with Hyalella azteca was: length > sexual maturation > survival. The lack of lethal effects on organisms may be related to temporal differences in sediment, acid-volatile sulfide, or organic carbon.

Montana↗
USGS1994

Physiological changes and tissue metal accumulation in rainbow trout exposed to foodborne and waterborne metals

Sublethal physiological effects and metal residue accumulation in tissues were measured in adult and juvenile rainbow trout fed a metal-contaminated diet and/or exposed to waterborne metals for 21 d. The consumption of metal-contaminated invertebrates from the Clark Fork River, Montana, significantly affected scale loss and metal accumulation in gut tissue of adult trout. Survival, scale loss, and metal accumulation in gill and kidney tissue were affected by exposure to a waterborne mixture of Cd, Cu, and Pb at twice the acceptable levels and Zn at the maximum acceptable level established by the U.S. Environmental Protection Agency for protection of aquatic wildlife. A combination of dietary and waterborne metals also caused lipid peroxidation in the kidney of adult fish and decreased whole-body potassium of juvenile trout. In general, metal accumulation in tissues was higher in gill and kidney with waterborne exposures and was higher in stomach and pyloric caeca with dietary exposure. And metal concentrations in juvenile whole-body tissues accumulated significantly with a combination of waterborne and dietary metals. Although some physiological changes were noted (scale loss, lipid peroxidation of kidney), an exposure time longer than 21 d is probably needed to observe more extensive physiological changes. Regardless, results from this study suggest that a full assessment of metal exposure to fish populations in natural systems must include evaluation of dietary as well as waterborne metal contamination.

Montana↗