In 1986, the Chernobyl nuclear disaster led to the largest release of radioactive materials into the environment in human history. It was a disaster for all forms of life, but the extent to which this incident affected the wildlife of Ukraine today was not entirely clear. Now, new research has shown that the levels appear to be good for the oriental tree frog (Hyla orientalis), as chronic exposure to the environment did not alter its lifespan, stress, or aging.
Given that, in the absence of humans, the area has become one of the largest nature reserves in Europe, what does this tell us about the fate of the animals that live there?
“I believe that the radiation levels currently found in the Chernobyl exclusion zone are not sufficient to cause noticeable organic damage to wildlife, at least in most of the Chernobyl zone,” said Pablo Burraco, study author and postdoctoral researcher at the Estación Biológica de Doñana, speaking to . IFLScience. “I’m not surprised by that.”
“In two weeks of working in some highly contaminated areas (for several hours every day), we accumulated the same level of radiation that a person would be exposed to in a single visit to the dentist. This is because the most dangerous radioactive isotopes released at the moment of the Chernobyl accident have a short half-life So radiation levels decrease quickly after several months or years.
Previous research has shown how frogs inside the Chernobyl exclusion zone rapidly evolved melanism to survive the historically high radiation levels in the area.
Photo credit: German Orizola
Burraco was part of a team led by German Orizola, which conducted fieldwork in Chernobyl between 2016 and 2018, examining animal populations with a particular focus on the eastern tree frog. They sampled Chernobyl’s frog populations, covering the entire gamut of radioactive contamination found in the area, and collected more than 200 male frogs.
The complete absence of humans allowed for a massive increase in the number of wild animals in present-day Chernobyl.
Pablo Burraco
In the laboratory, they assessed the frogs’ ages, the amount of radiation they absorbed, and levels of the stress hormone corticosterone, and determined the frogs’ rate of aging using telomere length as a marker.
The results showed no difference between the age, aging rate, and stress indicators of Chernobyl tree frogs compared to those living in control areas without radiation, indicating that radiation levels in the area are no longer sufficient to cause chronic damage.
The authors say the findings reinforce the role of the Chernobyl Exclusion Zone as a wildlife refuge that must be preserved, especially since the current impact of the accident appears to be manageable for frogs.
Searching for frogs in the Chernobyl Exclusion Zone, one of the largest nature reserves in Europe.
Photo credit: German Orizola
“Even if a small reduction in lifespan is observed in the wild, the ecological and evolutionary consequences may be low (something to be tested but very likely!),” Burraco said. “The complete absence of humans has allowed a massive increase in the number of wildlife in present-day Chernobyl.”
Today’s low levels of radiation are crucial, but frogs have adapted to survive at historical levels as well. A previous study Burraco was involved in revealed the amazing way melanotic species evolved, switching from green to black in a way that could protect against radiation, but we don’t yet know if this is related to how well they perform. today.
“It may be related to pigmentation in frogs, but we have not explored this possibility yet,” Burraco said. “My impression is that differences in pigmentation would have been more important when the accident occurred in order to survive the very high radiation levels of the time, but I agree that it may still play a role today.”
Dorsal skin illumination in eastern tree frogs inside (left) and outside (right) the Chernobyl exclusion zone.
Image credit: P. Burraco and G. Orizaola, Evolutionary Applications 2022 (CC BY 4.0)
The team wants to continue their work so they can best assess the current impact of the incident on wildlife, but science in the area is now under a new kind of threat.
“Unfortunately, we had to stop work at Chernobyl,” Buracko added. He added: “The (illogical) war taking place in Ukraine has destroyed bridges in that region, and forced many of our collaborators to flee to other countries or regions inside Ukraine, and it is unclear whether movement within the exclusion zone is safe due to the possible presence of counter-mines.” For individuals.”
The study was published in the journal Biology Letters.
