Effects of chronic γ-irradiation on growth and sexual maturation of the Tohoku hynobiid salamander, Hynobius lichenatus

Environmental radiobiology of amphibians - knowledge gaps to be filled using cell lines

Amphibians are facing an unprecedented level of population declines worldwide. The causes run the gamut from habitat loss and succumbing to opportunistic pathogen infections to vulnerability to toxic pollutants and ultraviolet (UV)-B radiation exposure. Anthropogenic activities including Chernobyl and Fukushima nuclear disasters and radioactive waste leakage into the environment raise the background radiation levels. Their immediate and chronic effects on amphibian populations are still being studied. However, the literature on environmental radiation effects on amphibian health still requires a lot more work. Laboratory and field works need to be conducted hand in hand in order to make informative and conclusive analyses to distinguish bad from good and harm from risk or to argue for or against the linear no-threshold model in radioprotection programs. Amphibian cell lines can help seek answers to important questions pertaining environmental radiobiology and amphibian health wherever they can suitably and effectively. The purpose of this work is to show that amphibian cell lines can 'rescue' important knowledge gaps in the literature, especially in the low-dose radiation mechanisms. Presently, there are 142 amphibian cell lines developed from six urodelans and 17 anurans. Amphibian cell lines can help expand and enrich the limited literature on environmental radiation effects on amphibians. They can be used to study mechanisms of radiation actions and discover reliable biomarkers for low-dose exposure. They can be used in environmental radiation monitoring and radioprotection programs. They can be used to determine the effects of co-exposure of IR and other stressors in the environment on amphibian health. They represent an ethical choice for amphibian conservation efforts in the current global amphibian declines. Lessons learned from cellular data can be useful guides to gain a better picture of effects occurring at the amphibian population and ecosystem levels.

Radiocesium (137Cs) concentrations in the two-toed amphiuma (Amphiuma means) and the lesser siren (Siren intermedia)

This study sought to determine radiocesium (¹³⁷Cs) concentrations in two species of aquatic salamanders - the two-toed amphiuma (Amphiuma means) and the lesser siren (Siren intermedia) on the Savannah River Site. Concentrations (¹³⁷Cs Bq/g, dry wt) of the two species were similar at both ¹³⁷Cs-contaminated (A. means = 0.733 ± 0.242, n = 5; S. intermedia = 0.839 ± 0.722, n = 5) and reference sites (A. means = 0.028 ± 0.020, n = 5; S. intermedia = 0.042 ± 0.027, n = 11). Salamanders captured in areas impacted by ¹³⁷Cs contamination exhibited significantly higher ¹³⁷Cs concentrations than individuals captured at reference sites (U = 146, p < 0.001). Salamander size (snout-vent length) was not correlated with whole-body ¹³⁷Cs. An analysis of our data using the ERICA tool suggests that negative impacts due to ¹³⁷Cs exposure are unlikely in these species. Overall, these data indicate that A. means and S. intermedia inhabiting contaminated sites bioaccumulate but do not biomagnify ¹³⁷Cs.