One key change that may have had an important effect on wildlife near Chernobyl is the sudden withdrawal of humans.
In areas once frequented by people, wolves, bears and bison now roam. Populations of deer, wild boar and elk have flourished. The number of wolves has even been estimated to be seven times higher in the exclusion zone compared to surrounding nature reserves, perhaps thanks to the abundant prey. Species including the Eurasian lynx have also returned to the area after vanishing long before the accident.
Brown bears, in particular, had not been sighted in this part of the world for more than 100 years until a camera trap caught one inside the exclusion zone in 2014. And, famously, groups of dogs apparently descended from pets abandoned after the 1986 disaster, are also plentiful in this area. Guards paid to prevent people illegally entering the exclusion zone are known to take care of these wandering canines. (Read more about the guards caring for Chernobyl’s abandoned dogs.)
Adapting to survive?
Leaving the other factors aside, is it possible that plants and animals near Chernobyl have actually evolved to cope with radiation? This is one of the most controversial claims of all. Some of the unusual characteristics of these organisms could be described as true adaptations in the evolutionary sense – that is, things they have inherited and give them an edge in their environment.
There are some hints that this has happened. A 2012 study, for example, found evidence that soybeans grown in the Chernobyl area had adapted to better cope with both radioactivity and heavy metal stress. Those bank voles inhabiting Chernobyl have also been found to have greater resistance to DNA damage.
Mousseau says that the black fungus growing within the stricken reactor building, where radiation levels remain very high, seems to be benefitting from that darker colour. “That’s significant, that’s positive evidence supporting the hypothesis that melanin provides some level of resistance to the effects of ionising radiation,” he says.
There’s still no answer to the question about whether darker frogs evolved their colour as an adaptation to protect them from radiation.
But various studies have suggested that some fungi become darker as an adaptive response to radiation. Experiments carried out on the International Space Station, for example, have shown fungi do this. But Mousseau adds that, in his opinion, there is zero evidence to support the idea suggested by some researchers that the fungus has evolved to harness the energy emitted by radiation to help it grow.
For Mothersill, it’s important to tease out whether mutations that emerged in plants and animals immediately after the accident have been passed down to successive generations of those organisms, even while radiation levels have fallen in the environment over time. Transgenerational mutations, if you like.
There is a hint of this in those bank voles again. Research from 2006 found that aberrations in the animals’ chromosomes persisted over successive generations even when voles were taken away from Chernobyl and allowed to reproduce in a contamination-free laboratory.
Elk have been documented in growing numbers following the evacuation of humans from the exclusion zone around Chernobyl.
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