Selenium Exposure Downstream of Surface Coal Mines: Toxicity and Effects on Fish Community Composition

Selenium (Se) is an essential micronutrient that can produce toxic effects in some fish and other aquatic organisms when present in amounts only slightly above the nutritional requirement. Se is released into aquatic systems at coal surface mines due to high weathering rates of disturbed bedrock and soil. Toxic Se effects (mainly developmental abnormalities) in wild fish populations have been confirmed downstream of mine sites, and coldwater fish species show variation in Se sensitivity. The long-term impacts of Se in heavily mined systems are largely unknown and there is concern over changes in fish community composition due to the differential Se sensitivity of coldwater fish species present in these streams. In this study, we investigated the extent of Se inputs and the effects of long-term Se exposure on fish community composition in current and historical coal mining areas of Alberta and British Columbia, Canada. We contrasted Se concentrations in water, sediments, primary producers, invertebrates, and fish, and compared fish community composition (relative species abundance) among reference streams, and streams with long-term impacts from reclaimed and active mines. We will discuss how species differences in Se sensitivity may lead to fish community-level effects where Se-tolerant species become relatively more abundant when Se concentrations are greater. This research contributes to the evaluation of current mine management and reclamation practices and aids in assessing Se risks for fish caused by expanding mining industry.