Lhe Chernobyl disaster marked world nuclear history. Since the accident of 1986, the rules of safety, surveillance and transparency have changed. But this drama has also upset our knowledge of the environment. Because if the blow to animal and plant species was expected, no one expected to see nature regain its rights so quickly. In a few decades, the exclusion zone has even become a refuge for biodiversity – lynx, wolves, bears… – and a laboratory for scientists.
It was while trying to observe the influence of this extreme environment on the fauna that two Spanish researchers, Pablo Burraco and German Orizaola, made a curious discovery in 2016. In the plant’s exclusion zone, their attention fell on black frogs. Specimens not completely unknown to them: the tree frog Hyla of the east has been widely described. Its cries, audible for miles, its life in the trees, near water points, have been well studied. “Except these were blacksays Pablo Burraco, postdoctoral fellow at the Donana biological station in Seville. We wondered if it could be related to the accident. »
In an article published on August 28 in the journal Evolutionary Applications, the two scientists answer clearly in the affirmative. It is indeed the extraordinary selection pressure provoked by ionizing rays that directed the evolution of amphibians from green to black. To demonstrate this, they had to return four years in a row to the red zone. “It is forbidden to stay there for more than a fortnight 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 radiation
The comparison is instructive. The more frogs come from highly irradiated areas, the darker their skin appears. By studying the quantity of cesium recorded in the months following the disaster and the current map, they were even able to clarify their conclusion: it is indeed the ionizing rays recorded in the months following the tragedy that guide the phenomenon.
By what mechanism? Here again, their answer is clear: melanin. The pigment abounds on the skin of black frogs. “It shouldn’t surprise usindicates Pablo Burraco. We can compare our observations to the skin coloration associated with sunlight in humans. » Above all, do not conclude that Blacks can safely whistle at the heart of the reactors. Especially since the way in which melanin dissipates the energy of ionizing rays remains to be studied.
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