TSUKUBA, Ibaraki Prefecture--A type of mollusk has disappeared from an area that stretches 30 kilometers along Fukushima Prefecture and includes the site of the crippled nuclear power plant, researchers said.
But they could not confirm if radioactive substances from the nuclear disaster led to the absence of the usually ubiquitous rock shells, according to the survey led by the National Institute for Environmental Studies (NIES).
“It will be necessary to conduct culture experiments to study how radioactive materials affect the habitat of rock shells,” said Toshihiro Horiguchi, a head researcher at NIES and a specialist in ecotoxicology.
Rock shells, a univalve with a 3-centimeter-long shell, live in reefs and are generally widely distributed along Japanese coasts as far north as southern Hokkaido.
Tsukuba-based NIES, the National Institute of Radiological Sciences and others studied the habitat of rock shells at 43 locations on the Pacific coast of Honshu ranging from Kuji, Iwate Prefecture, to Tateyama, Chiba Prefecture, between April and August 2012.
According to the study, rock shells could not be found in 16 locations, including eight straight sites over 30 km from Futaba town, just north of the stricken nuclear plant, to Hirono.
Horiguchi said rock shells were found off municipalities that were hit hard by the tsunami following the Great East Japan Earthquake on March 11, 2011, such as Soma and Minami-Soma in Fukushima Prefecture.
He said it was unlikely that the rock shells’ disappearance was caused only by the tsunami.
The survey results were presented March 27 at the spring meeting of the Japanese Society of Fisheries Science in Tokyo.
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