Butterflies in the area are showing signs of severe mutations, signaling that the disaster is affecting the ecosystem. (Photo: Joji Otaki)

Researchers from Japan found the first evidence of long-term repercussions from the Fukushima nuclear power plant disaster. Butterflies in the area are showing signs of severe mutations, signaling that the disaster is affecting the ecosystem.        

The Fukushima Daiichi nuclear power plant melted down after an 8.9 magnitude earthquake and following tsunami hit Japan in March. The tsunami flooded the facility's generators and destroyed the plants cooling system, which caused radiation to be released into the surrounding areas.

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Researchers collected 144 specimens of the pale grass blue butterfly, a species commonly seen in Japan, two months after the disaster and found that 12 percent showed signs of mutation and abnormalities, including antennae disfigurement, small wings and a change in color patterns.

When the researchers collected more than 200 more specimens 6 months later, they found that ballooned to 28 percent, with 52 percent of their offspring affected.

"Our results are consistent with the previous field studies that showed that butterfly populations are highly sensitive to artificial radionuclide contamination in Chernobyl and Fukushima," researchers wrote in the study. "Together, the present study indicates that the pale grass blue butterfly is probably one of the best indicator species for radionuclide contamination in Japan."

Researchers said that the mutated butterflies could be the tip of the iceberg.

"Since we've seen these effects on butterflies, it's easy to imagine that it would also have affected other species as well," Joji Otaki, study author and researcher from the University of the Ryukyus in Okinawa, told NBC News.  "It's pretty clear that something has gone wrong with the ecosystem."

Otaki told the Japan Times that more research needs to be conducted.

"Sensitivity (to irradiation) varies between species, so research should be conducted on other animals," he said.

As the butterflies and other animals continue to breed, the mutations will become more visible.

"Effects of low level radiation is genetically transferred through generation, which suggests genetic damage. I think it's clear that we see the effects passed on through generations," Otaki told NBC News.

However, he stressed that people do not need to worry.

"Humans are totally different from butterflies and they should be far more resistant [to the radiation]," Otaki said.