British Columbia Mine Reclamation Symposium

Selenium in the Elk River Basin, British Columbia : a review of findings and discussion of implications for assessment and management McDonald, Leslie E.; Strosher, Mark M.


Despite 100 to 200 fold increases in waterborne selenium below coal mine operations in the Elk River basin, concentrations in sediments, attached algae, aquatic insects and fish tissues were only 2 to 5 times greater than reference sites. Selenium concentrations in Westslope cutthroat trout skeletal muscle and liver were higher in the near field populations and exceeded published toxic effects thresholds for fish tissue. Further study in 1998 compared the frequency of embryonic deformities and mortalities with the; Se concentration in the eggs of individual female cutthroat trout in an exposed and a reference population. Egg selenium concentrations ranged from 2.0 to 8.8 μg/g dry wt. in reference fish, and 8.7 to 81.3 μg/g dry wt. in exposed fish. Both reference and exposed populations showed low frequencies of deformities (<2.5%) and occasional high frequencies of mortalities (up to 100%) but no correlation with egg selenium. The lack of response in this population of cutthroat trout suggests an evolved tolerance to selenium at levels reported elsewhere to cause significant toxic effects. The findings of the Elk River studies provide evidence that development and application of universal criteria must be done with great caution. Management decisions made on residue data alone may be unnecessarily under or over protective. At this state it appears necessary that site specific studies must be carried out to verify the absence: or presence of effects.

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