The pale grass blue butterfly: Impacts of a radioactive disaster

Photo Courtesy of CharlesLam

A publication in the Journal of Scientific Reports this week has produced some prominent data for the understanding of the potential ecological and biological impacts of the Fukushima Dai-ichi Nuclear Power Plant disaster.  The study has demonstrated the devastating impacts radioactivity has had upon one species of butterfly (Zizeeria maha), and it is suggested that the effects on this particular organism is an indicator of the impacts upon many other taxa.  

Butterflies belonging to the order Lepidoptera play an integral role in the world’s biological ecosystems. As vital pollinators, and prey for many other species within ecosystem networks, butterflies are highly reliable indicators of biodiversity. Species are highly adaptable at thriving and flourishing in diverse climates and a range of environments, however the release of radioactivity into the environment as a result of the Fukushima Dai-ichi Nuclear Power Plant disaster has had devastating impacts on regional butterfly populations.

The pale grass blue butterfly (Zizeeria maha) is a common species found throughout Japan; however mutational abnormalities have been discovered since the nuclear disaster in May 2011 caused by the Tōhoku earthquake and tsunami. Two months after the accident, a team of research scientists visited 10 locations throughout the region, collecting 144 adult pale grass blue butterfly specimens.  Mild abnormalities in antennae length and eye formation were initially evident; however the true extent of physiological damage did not become apparent until the F₁ offspring generation, which demonstrated even more extensive mutational defects. Rates of abnormalities rose further to 33.5% in the F₂ generation offspring, indicating that the radioactivity had not only caused physiological abnormalities but had caused damaging genetic mutations. 

These abnormalities were reproduced artificially and experimentally through low dose exposures to radioactivity, reaffirming the effects of the Fukushima disaster upon butterfly populations. Survival curves within the lab indicated dose dependency of radiation, with mortality rates of larvae, pre-pupae, and pupae and the abnormality rate of adults correlating with higher levels of radiation. These findings are extremely worrying for the long term impacts on the fragile ecosystems of Japans radioactive region. It is evident that as these indicator species have been heavily affected, so too will the entire biological networks within the region, resulting in long term implications for the future of many species.

Volunteers interested in the conservation and ecology of butterflies can help make a contribution to scientific studies by participating in butterfly projects in both Cambodia and Costa Rica with Frontier.

By Laura Burton