Adverse effects of ecologically relevant dietary mercury exposure in southern leopard frog (Rana sphenocephala) larvae

Southern leopard frog (Rana sphenocephala) larvae were exposed to experimental diets supplemented with aufwuchs from control and mercury-enriched mesocosms combined in proportions intended to mimic mercury concentrations and speciation in aufwuchs observed from aquatic systems contaminated by atmospheric deposition. Observations on rates of mortality, malformation, and larval growth and development were made for 254 d. Increased incidence of mortality, malformation, and changes in growth and development were observed at concentrations that reflect the highest concentrations expected in the amphibian diet from atmospheric deposition (1,500-3,300 ng Hg/g dry wt). The results of this study are probably more ecologically realistic than results obtained from previous studies of aqueous mercury toxicity and suggest that dietary mercury exposure in habitats contaminated primarily by atmospheric deposition has the potential to cause adverse effects in amphibian larvae.