Studying radiation in the Fukushima Exclusion Zone can be a dangerous business for some – but not for slithering snakes. In a new study, scientists demonstrated how Japan’s resident rat snakes can be used to gauge levels of radiation left by the 2011 Fukushima Daiichi nuclear disaster.
As reported in the journal Ichthyology & Herpetology in July, researchers from the University of Georgia discovered that radioactive contamination may have some influence on the day-to-day movements of the snakes. Therefore, the species could be used as a tool to indicate radiation levels in an ecosystem’s soil.
Snakes are especially effective at measuring soil contamination as they slither on their bellies, making full contact with the ground below. The relatively limited movement of rat snakes, plus their long life span, also affirms their position as ideal candidates in the eyes of the research team.
"Snakes are good indicators of environmental contamination because they spend a lot of time in and on soil," James C Beasley, study author and associate professor at the University of Georgia, explains in a statement. "They have small home ranges and are major predators in most ecosystems, and they're often relatively long-lived species."
The researchers toyed with this idea of using snakes to measure radioactive soil contamination in a previous study published in 2020. Building on this, the researchers tracked nine rat snakes with GPS transmitters for over three months in the Abukuma Highlands, around 24 kilometers (15 miles) northwest of the Fukushima Daiichi Nuclear Power Plant.
Despite moving an average of just 65 meters (around 213 feet) per day, the team found the snakes were picking up subtle yet significant levels of radionuclides – clearly, the radiation wasn't killing the snakes, but further work to analyze potential risks to their health is needed.
They found the snakes avoided the interior of conifer forests, preferring to hang out along the edges of deciduous forests and inside abandoned buildings. Most snakes also spent time in abandoned barns and sheds – the researchers speculated this helped them shield themselves from contamination in the surrounding soil.
"Our results indicate that animal behavior has a large impact on radiation exposure and contaminant accumulation," explained Hanna Gerke, lead study author from the Savannah River Ecology Laboratory and Warnell School of Forestry and Natural Resources at the University of Georgia.
"Studying how specific animals use contaminated landscapes helps increase our understanding of the environmental impacts of huge nuclear accidents such as Fukushima and Chernobyl," added Gerke.