August 14, 2012
Radiation Has Caused Abnormalities In Butterflies Near Fukushima
April Flowers for redOrbit.com - Your Universe Online
Exposure to radioactive material released into the environment has caused mutations in butterflies found in Japan, according to a new study out of the University of the Ryukyus in Okinawa.
An increase in leg, antennae and wing shape mutations among butterflies collected following the 2011 Fukushima accident were found by the study, published in the journal Scientific Reports. Laboratory experiments exposed the link between these mutations and radioactive material.
The Fukushima Daiichi accident was the largest nuclear disaster since the Chernobyl incident in 1986. The Fukushima disaster was the result of equipment failures, meltdowns, and radioactive materials released after the Tohoku earthquake and tsunami that hit Japan on March 11, 2011.
Two months after the Fukushima accident, a team of Japanese researchers collected 144 adult pale grass blue (Zizeeria maha) butterflies from 10 locations in Japan, including the Fukushima area. These adult butterflies would have been larvae during the accident.
By comparing mutations found on the butterflies collected from different sites, the team found that areas with higher levels 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," lead researcher Joji Otaki told BBC News reporter Nick Crumpton. "In that sense, our results were unexpected."
By breeding these captured butterflies in laboratories 1,750 km away from Fukushima, the team noticed a suite of abnormalities that had not been seen in the previous generation such as malformed antennae, which the insects use to explore their environment and seek out mates.
Six months later, the team again collected butterflies from all ten sites. The Fukushima butterflies showed a mutation rate more than double that of those found immediately after the accident.
This higher rate of mutation comes from eating contaminated food and from mutation of the parent's genetic material being passed on to the next generation, even though the specific mutations were not evident in the previous generations' adult butterflies.
The team has been studying this particular species of butterfly for more than ten years and was considering the species as an "environmental indicator" before the accident, as previous work had shown it is very sensitive to environmental changes.
"We had reported the real-time field evolution of color 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.
The team found, however, that the radionuclides released from the accident were still affecting the development of the butterflies, 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. "These observations of mutations and morphological abnormalities can only be explained as having resulted from exposure to radioactive contaminants."
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.