To gain a better understanding of the environmental impacts of the 2011 nuclear accident in Fukushima, Japan, an international research team monitored rat snakes as reptilian bioindicators of radiocontamination.

Rat snakes are abundant in Japan, travel short distances and can accumulate high levels of radionuclides. Their limited movement and close contact with contaminated soil are key factors in their ability to reflect the varying levels of contamination in the affected zone. Researchers identified 1,718 locations of these snakes while tracking them for over a month in a region approximately 15 miles northwest of the Fukushima Daiichi Nuclear Power Plant.

The mobility of nine rat snakes was monitored using a combination of GPS transmitters and manual very-high frequency tracking. Transmitters were placed on the rear back of these research assistants with tape and superglue.

Each moved an average of just 65 m per day, and most spent time in abandoned barns and sheds, which can help shield them from contamination in the surrounding soil. However, their risk of exposure increases in winter as snakes seek shelter underground, close to the more heavily contaminated soils.

The results published by scientists from the University of Georgia, Fukushima University and Norwegian University of Life Sciences in Ichthyology & Herpetology reinforce previous research, which indicated that radiocesium levels in snakes were correlated with radiation levels in the soil where the snakes were captured. Future work to clarify the link between the micro-habitat use of species like snakes and their contaminant exposure, as well as the potential health risks to snakes and other wildlife due to increased radiation exposure, will be critical to understanding the effects of the Fukushima Daiichi accident on local wildlife populations.