The Chernobyl disaster has marked global nuclear history. Since the 1986 accident, safety, surveillance, transparency rules have evolved. But this drama has also changed our knowledge of the environment. Because if the blow to animal and plant species was expected, no one thought of seeing nature so quickly resume their rights. In a few decades, the exclusion zone has even become a refuge for biodiversity – lynx, wolves, bears … – and a laboratory for scientists.
It is moreover by trying to observe the influence of this extreme environment on fauna that two Spanish researchers, Pablo Burraco and German Orizaola, made, in 2016, a curious discovery. In the exclusion area of the power plant, their attention was paid to black frogs. Specimens not quite unknown for them: the Hyla Orientalis arboreal frog has been widely described. His cries, audibles for miles, his life in the trees, near water points, have been well studied. “Except that these were black,” says Pablo Burraco, postdoctoralizing at the biological station Donana de Seville. We wondered if it could be linked to the accident. “
In an article published on August 28 in the journal Evolutionary Applications, the two scientists clearly respond in the affirmative. It is the extraordinary selection pressure caused by the ionizing rays that led the evolution of amphibians from green to black. To demonstrate it, they had to return four years in the red zone. “It is forbidden to stay there for more than fifteen days a year, and we wanted to collect enough samples to carry out physiological, genetic and morphological approaches,” continues the researcher. They were thus able to collect 189 individuals from 12 localities, inside and outside the exclusion perimeter.
Exposure to ionizing rays
The comparison is edifying. The more the frogs come from highly irradiated areas, the more dark their skin. By studying the amount of cesium noted in the months following the disaster and the current card, they were even able to specify their conclusion: it is indeed the ionizing shelves recorded in the months that followed the drama that guide the phenomenon.
by which mechanism? Again, their answer is final: melanin. The pigment abounds on the skin of black frogs. “It should not surprise us,” says Pablo Burraco. We can compare our observations to the coloring of the skin associated with the sun’s rays in humans. “Above all, the blacks can sink down to the heart of the reactors. Especially since the way melanin dissipates the energy from ionizing rays remains to be studied.
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