Accumulation of waterborne selenium by rainbow trout (Salmo gairdneri), eggs, fry and juveniles.

The effect of waterborne selenite levels on selenium accumulated by different developmental stages of rainbow trout (Salmo gairdneri) was studied using(75)SeO 3 (=) as a tracer. All stages readily accumulated selenium at both high and low concentrations, but the rate of accumulation increased as the trout developed from the egg to the juvenile feeding stage. The low rate of selenium accumulation by embryos seemed to be related more to a lack of gills than to the presence of a chorion. The bioconcentration factor (the ratio of tissue-to-water concentrations) declined in all groups with increased waterborne selenium levels; accumulation rates appeared limited by cell permeability. At low levels of waterborne selenium (0.4µg/l), the total accumulated was small relative to existing body burdens and unlikely to contribute significantly to the nutritional requirement for selenium. High levels (45.6µg/l), however, caused considerable selenium accumulation and may be sufficient to overcome the effects of low dietary selenium.