Effect of selenium pretreatment on the acute toxicity of mercury in the mussel Brachidontes variabilis

Abstract

      The interaction of selenium with mercury has been stu­died in the mussel Brachidontes variabilis. The 48 hr lethal concentrations (LC₅₀) were determined for mercury in groups subjected to different selenium pretreatments (250, 500, and 1000 µg. l^1- Se) 24 hours before exposure to various concentrations of mercuric chloride. The LC₅₀ value was also determined in the group exposed solely to mercury. Pretreatment with selenium was found to significantly de­crease mercury toxicity. Thus the protective effect of sele­nium against the toxicity of mercury was observed in mus­sels. The degree of protection increased with increasing pre­treatment concentrations. The LC₅₀ values were calculated by using the        B l i s s  method as well as a graphical method.