Use of toe clips as a nonlethal index of mercury accumulation and maternal transfer in amphibians.

Nonlethal indices of contaminant exposure can facilitate research on the accumulation and effects of contaminants in wildlife. Here, we tested the efficacy of using amputated toes ("toe clips"), a common byproduct when marking amphibians in population and genetic studies, to determine mercury (Hg) concentrations in amphibians. We examined total mercury (THg) concentrations in American toads (Bufo americanus) collected along a contamination gradient at a Hg-contaminated field site. We found significant positive correlations between toe THg and blood THg concentrations in adult males and females collected in two different years. We also found that blood and toe clips could be used to predict maternal transfer of Hg, an important mechanism of reproductive toxicity in wildlife. Maternal toe THg concentrations were more highly correlated with egg THg concentrations than were maternal blood THg concentrations. Our results indicate that amputated toes are effective for identifying Hg concentrations in amphibians.