Selenium is a trace element normally found in surface waters at concentrations of approximately 0.1-0.3 μg/L (Lemly 1985). At slightly elevated concentrations (1-5 μg/L), it can bioaccumulate in the aquatic food chain, becoming highly toxic to fish and wildlife (Lemly and Smith 1987). Sandholm et al. (1973) found that fish accumulate selenium primarily through the food chain, although uptake across gills is very efficient at low waterborne concentrations (Hodson and Hilton 1983). Selenium can also be passed to offspring from maternal transfer to the eggs where it is possible to cause complete reproductive failure (Gillespie and Baumann 1986; Coyle et al. 1993; Lemly 1993).