日本科学家研究发现，福岛核事故之后，由于受到放射性物质的影响，日本的蝴蝶品种出现了翅膀变小、眼睛发育不规则等明显的变异现象。2011年3月福岛核事故后两个月后，研究人员从日本10个不同地区采集了144只成年酢漿灰蝶样本进行研究。研究发现，核辐射越严重地区的蝴蝶，其翅膀和眼睛的变异现象越明显。
研究组的一位研究人员表示，之前一直都认为昆虫的抗辐射能力很强，因此该研究得出的结论有些出人意料。6个月之后，研究人员再次从上述10个地区采集蝴蝶样本，结果发现福岛地区的蝴蝶变异几率变成了原来的两倍。研究人员指出，变异几率上升的原因一部分是因为摄入受辐射的食物，另一个原因就是基因遗传。受到辐射初期没有表现出变异症状的蝴蝶，它们的下一代可能就会表现出明显的变异症状了。该研究结果表明，虽然福岛地区的辐射残留物质已经明显减少，但对动物和环境的辐射影响仍然存在。
Exposure to radioactive material released into the environment has caused mutations in butterflies found in Japan, a study suggests.
Scientists found an increase in leg, antennae and wing shape mutations among butterflies collected following the 2011 Fukushima accident.
The link between the mutations and the radioactive material was shown by laboratory experiments, they report.
The work has been published in the journal Scientific Reports.
Two months after the Fukushima Daiichi nuclear power plant accident in March 2011, a team of Japanese researchers collected 144 adult pale grass blue (Zizeeria maha) butterflies from 10 locations in Japan, including the Fukushima area.
When the accident occurred, the adult butterflies would have been overwintering as larvae.
Unexpected results
By comparing mutations found on the butterflies collected from the different sites, the team found that areas with greater amounts of radiation in the environment were home to butterflies with much smaller wings and irregularly developed eyes.
"It has been believed that insects are very resistant to radiation," said lead researcher Joji Otaki from the University of the Ryukyus, Okinawa.
"In that sense, our results were unexpected," he told BBC News.
The Japanese researchers have been studying the species for more than a decade Prof Otaki's team then bred these butterflies within labs 1,750km (1,090 miles) away from the accident, where artificial radiation could hardly be detected.
It was by breeding these butterflies that they began noticing a suite of abnormalities that hadn't been seen in the previous generation - that collected from Fukushima - such as malformed antennae, which the insects use to explore their environment and seek out mates.
Six months later, they again collected adults from the 10 sites and found that butterflies from the Fukushima area showed a mutation rate more than double that of those found sooner after the accident.
The team concluded that this higher rate of mutation came from eating contaminated food, but also from mutations of the parents' genetic material that was passed on to the next generation, even though these mutations were not evident in the previous generations' adult butterflies.
The team of researchers have been studying that particular species butterfly for more than 10 years.
They were considering using the species as an "environmental indicator" before the Fukushima accident, as previous work had shown it is very sensitive to environmental changes.
"We had reported the real-time field evolution of colour patterns of this butterfly in response to global warming before, and [because] this butterfly is found in artificial environments - such as gardens and public parks - this butterfly can monitor human environments," Prof Otaki said.
But the findings from their new research show that the radionuclides released from the accident were still affecting the development of the animals, even after the residual radiation in the environment had decayed.
"This study is important and overwhelming in its implications for both the human and biological communities living in Fukushima," explained University of South Carolina biologist Tim Mousseau, who studies the impacts of radiation on animals and plants in Chernobyl and Fukushima, but was not involved in this research.
"These observations of mutations and morphological abnormalities can only be explained as having resulted from exposure to radioactive contaminants," Dr Mousseau told BBC News.
The findings from the Japanese team are consistent with previous studies that have indicated birds and butterflies are important tools to investigate the long-term impacts of radioactive contaminants in the environment.
