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| The study found that mutation rates were much higher among butterfly collected near Fukushima |
Exposure to
radioactive material released into the environment have 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.
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