Aqueous exposures to selenomethionine (SeMet), the major form of selenium (Se) in the diet, represent a rapid and simplified method for determining the embryotoxic effects of SeMet. Using fathead minnows (Pimephales promelas) as a model test organism, the objective of this study was to evaluate the effects of waterborne exposure to elevated SeMet on embryos from fertilization to swim-up. Newly fertilized embryos were exposed for 6 days to 30, 90, 270, 810, 2430, 7290, 21,870, and 65,610 µg Se/L (as SeMet). Survival, hatchability, days to hatch, and the frequency and severity of deformities (total and type) were quantified. SeMet exposure reduced hatchability and days to hatch at concentrations ≥ 21870 µg/L. Significant decreases in survival and significant increases in the incidence and severity of deformities were observed at concentrations ≥ 810 µg/L. The results suggest that early life-stage fathead minnows are more tolerant to aqueous exposure to SeMet compared to medaka and zebrafish.
Keywords: Aqueous; Deformities; Embryo; Fish; Selenium; Selenomethionine.