Pale grass blue butterflies are very sensitive to environmental changes; therefore, scientists use them to test the effects of global warming on animals. This is why a team of Japanese researchers chose this species to check the biological impact of the 2011 Fukushima nuclear disaster, with disturbing results: a small percentage of the butterflies that were in Fukushima during the accident show mild abnormalities, but these are bigger and more common among their offspring, even if they are taken away from the irradiated zone.
The scientists first took a number of butterflies in May 2011 (two months after the accident), noticing smaller wings and damaged eyes in some cases. Then, they bred these butterflies in a place were no radiation was detected; their offspring showed more sever malformations, including damaged antennae. Around four months later, in September and October 2011, they again collected pale blue butterflies from different locations. Now the rate of malformations was double than the first time.
It remains to be seen how radiation may have affected humans, though it may take decades before we know the true extent of the damage.
Atsuki Hiyama, Chiyo Nohara, Seira Kinjo, Wataru Taira, Shinichi Gima, Akira Tanahara, & Joji M. Otaki (2012). The biological impacts of the Fukushima nuclear accident on the pale grass blue butterfly Scientific Reports DOI: 10.1038/srep00570
Natural Disaster and Nuclear Crisis in Japan