In 2011, a 15-meter tsunami disabled the power supply and cooling at Fukushima Daiichi Power Plant, damaging three nuclear reactors in the process. The accident was rated a seven, which is the highest level on the International Nuclear and Radiological Event Scale.

Now, a decade later, scientists have partnered with snakes to measure radioactive contamination in the region. A team of researchers from the University of Georgia discovered that rat snakes native to the region are an effective bioindicator of residual radioactivity, which means they can reflect the health of their local ecosystem.

“Snakes are good indicators of environmental contamination because they spend a lot of time in and on soil,” says James Beasley, an advisor for the study. “They have small home ranges and are major predators in most ecosystems, and they’re often relatively long-lived species.”

Plus, rat snakes don’t venture too far, traveling only around 65 meters at a time, and seek shelter underground during winter months which means they’re even more exposed to the heavily contaminated soils allowing them to accumulate high levels of radionuclides, which can be used to determine varying levels of contamination in their habitat.

This makes them far better indicators of local contamination than other animal species in the area such as wild boars, songbirds, or the East Asian raccoon dog.

The study’s lead author, Hannah Gerke, says that the results of their study “indicate that animal behavior has a large impact on radiation exposure and contaminant accumulation.” “Studying how specific animals use contaminated landscapes helps increase our understanding of the environmental impacts of huge nuclear accidents such as Fukushima and Chernobyl.”

Source Study: Ichthyology & Herpetology—Movement behavior and habitat selection of rat snakes (Elaphe spp.) in the Fukushima Exclusion Zone