Birds Are Developing Resistance To Radiation Leftover From Chernobyl Disaster
It's been almost 28 years since the Chernobyl nuclear disaster in Ukraine (formerly part of the Soviet Union) and biologists are still trying to understand the effects of radiation exposure to the surrounding ecosystem. Recent research suggests, however, that the radiation may not have been as harmful to the fauna as previously thought, and that it may have even benefited the area's bird population.
The study, published in the journal Functional Ecology, provides some of the first evidence that wild animals adapt to ionizing radiation, showing that birds with less pheomelanin, a pigment in their feathers, are better able to adapt to radiation exposure.
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"Previous studies of wildlife at Chernobyl showed that chronic radiation exposure depleted antioxidants and increased oxidative damage," said lead author Dr. Ismael Galván, of the Spanish National Research Council, in a press release. "We found the opposite - that antioxidant levels increased and oxidative stress decreased with increasing background radiation."
Although the Chernobyl disaster occurred in 1986, the exclusion zone around the former power plant contains high amounts of radiation. This presents a perfect testing ground for biologists to analyze the effects of high levels of ionizing radiation on wild animals.
Experiments on humans and other animals have shown that they're able to eventually develop radiation resistance over time. The resistance develops through repeated exposure to low levels of radiation, and is supposed to help when they're exposed to larger levels. The effect, however, had never been observed in wild populations.
For their study, the researchers used mist nets to capture 152 birds comprising 16 different species - such as barn swallows, wood warblers, blackcaps, and whitethroats - from eight sites within and near the exclusion zone. They measured background radiation levels at each site, and took feather and blood samples before releasing the birds.
The blood samples were then measured for levels of the antioxidant glutathione, oxidative stress, DNA damage, and their feathers' melanin pigments - the most common animal pigments. They found that higher levels of pheomelanin, which make their feathers red, were associated with a lower tolerance for radiation exposure - as more pheomelanin is produced, more antioxidants are used up.
The team then analyzed the results by taking into account radiation levels within individual birds rather than species averages, making it a much more sensitive way to analyze biochemical responses to radiation. The results revealed that with increasing background radiation, the birds' body condition and glutathione levels increased, and oxidative stress and DNA damage decreased. These results also supported their findings that more pheomelanin meant a poorer body condition, as oxidative stress and DNA damage was more likely.
"The findings are important," Galván said, "because they tell us more about the different species' ability to adapt to environmental challenges such as Chernobyl and Fukushima."
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