Some effects of Selenium on the growth and survival of larval stages of the American oyster, Crassostrea virginica.
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Acute bioassays on early life stages of Crassostrea virginica indicate that selenium was toxic at all concentrations tested. Toxic effects are most significant at 10 ppm, particularly in continuous exposures. When initiation of exposure was delayed until the 48-hour straight hinge stage, veliger larvae were highly resistant to selenium, showing only a 16% mortality differential between 10 ppm and controls at the termination (120 hours) of the experiment. Some toxicity however, was apparent. In continuous exposures, selenium proved to be highly toxic, with effects compounded over time. Survival in 10 ppm was less than 1% after 48 hours and decreased to 0.14% after 72 hours. In all concentrations, survival was less than that in controls. The estimated 72 hr LC50 was 0.12 ppm. 0.001 selenium was slightly toxic and mortalities at this concentration were within 15% of control values in all experiments. Growth rates were largely unaffected by selenium exposure. Mean larval lengths were not significantly different among concentrations in both short-term (3 days) and long-term (10 days) experiments.