Mercury Concentrations in the Two-Toed Amphiuma ( Amphiuma means ) and the Lesser Siren ( Siren intermedia ): Validating Non-lethal Sampling Methods in Southeastern Aquatic Salamanders

The global decline of amphibians is a major conservation issue. Many stressors are recognized for this decline including exposure to environmental contaminants. Mercury (Hg) is an environmental contaminant that bioaccumulates in wildlife and can cause a variety of negative impacts across taxa, including amphibians. Amphiuma and Siren spp. can comprise a large portion of biomass within their respective ecosystems, and thus, likely serve as important predators or prey in wetland communities. However, due to their cryptic nature, little is known about their ecology, diet, and accumulation potential. We sought to validate a nonlethal sampling method to quantify total mercury (THg) in two enigmatic species of aquatic salamanders: the two-toed amphiuma (Amphiuma means) and the lesser siren (Siren intermedia). We examined relationships between THg content in lethal (whole-body) and nonlethal (tail clip) samples. Tail clips were statistically significant predictors of whole-body THg (all p < 0.001), explaining 84–89% of variation in whole-body THg. Average whole-body THg (mg/kg) did not significantly differ between the two species (p = 0.97), and overall, they had similar whole-body THg content (S. intermedia = 0.330 ± 0.04, n = 18; A. means = 0.333 ± 0.07, n = 11). To our knowledge, these data represent the first reported Hg burdens in A. means and S. intermedia.