A range of scientific studies at Fukushima have begun to reveal the impact on the natural world from the radiation leaks at the power station in Japan caused by an earthquake and tsunami in 2011.
Biological samples were obtained only after extensive delays following the 1986 Chernobyl nuclear power plant meltdown, limiting the information which could be gained about the impact of that disaster.
Scientists, determined not to repeat the shortcomings of the Chernobyl studies, began gathering biological information only a few months after the meltdown of the Daiichi power plant in 2011.
Results of these studies are now beginning to reveal serious biological effects of the Fukushima radiation on non-human organisms ranging from plants to butterflies to birds.
A series of articles summarising these studies has now been published in the Journal of Heredity. These describe widespread impacts, ranging from population declines to genetic damage to responses by the repair mechanisms that help organisms cope with radiation exposure.
“A growing body of empirical results from studies of birds, monkeys, butterflies, and other insects suggests that some species have been significantly impacted by the radioactive releases related to the Fukushima disaster,” says Dr Timothy Mousseau of the University of South Carolina, lead author of one of the studies.
Common to all of the published studies is the hypothesis that chronic (low-dose) exposure to ionizing radiation results in genetic damage and increased mutation rates in reproductive and non-reproductive cells.
One of the studies documented the effects of radiation on rice by exposing healthy seedlings to low-level gamma radiation at a contaminated site in Fukushima Prefecture.
After three days, a number of effects were observed, including activation of genes involved in self-defense, ranging from DNA replication and repair to stress responses to cell death.
“The experimental design employed in this work will provide a new way to test how the entire rice plant genome responds to ionizing radiation under field conditions,” says Dr Randeep Rakwal of the University of Tsukuba in Japan, one of the authors of the study.
Another team of researchers examined the response of the pale grass blue butterfly, one of the most common butterfly species in Japan, to radiation exposure at the Fukushima site.
They found size reduction, slowed growth, high mortality and morphological abnormality both at the Fukushima site and among laboratory-bred butterflies with parents collected from the contaminated site.
“Non-contaminated larvae fed leaves from contaminated host plants collected near the reactor showed high rates of abnormality and mortality,” says Dr Joji Otaki of the University of the Ryukyus in Okinawa, Japan.
Some of their results suggested the possible evolution of radiation resistance in Fukushima butterflies as well.
A review of genetic and ecological studies for a range of other species at both Chernobyl and Fukushima (Mousseau 2014) revealed significant consequences of radiation. Population censuses of birds, butterflies, and cicadas at Fukushima showed major declines attributable to radiation exposure. Morphological effects, such as aberrant feathers on barn swallows, were also observed. The authors suggest that long-term studies at Chernobyl could predict likely effects in the future at the Fukushima site.
The scientists say there is an urgent need for greater investment in basic scientific research of the wild animals and plants of Fukushima.