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Field Observations Show Decline of Japan’s Intertidal Biota Near Site of the Fukushima Disaster

By Jay T. Cullen

Shells of sea snails (Thais clavigera); one of the organisms missing from near the Fukushima Dai-ichi Nuclear Power Plant

The purpose of this post is to report on a newly published, peer-reviewed study in the open access journal Scientific Reports that uses field observations to determine how intertidal species abundance and diversity were affected by the 2011 earthquake, tsunami and Fukushima Dai-ichi Nuclear Power Plant (FDNPP) disaster.  This post is part of an ongoing series dedicated to summarizing the results of scientific studies aimed at understanding the impact of the FDNPP disaster on ecosystem and public health.  Horiguchi and colleagues surveyed intertidal marine organisms and made measurements of artificial radionuclides in specimens in 2011, 2012 and 2013.  They found that in 2012 the number of intertidal organisms was lower closer to the FDNPP than farther away and that the sea snail (Thais clavigera) was absent from sampling locations <30 km from the FDNPP.  Because sea snails were found in other rocky habitats affected by the tsunami in 2011 the absence of these organisms in 2012 near the plant might be related to the FDNPP disaster.  In 2013 both the numbers of organisms and diversity of species were found to be lower at sites within several kilometers south of the FDNPP site.  While, according to the authors, there is no clear explanation for the findings at present it is clear that the intertidal biota has been impacted close to the FDNPP since the disaster.  The authors conclude that:

  1. it is unlikely that the tsunami was solely responsible for changes in the intertidal communities given the distribution of sea snails
  2. other causes might include acute or sub-acute toxicities from the largest leaks from the FDNPP site in March-April 2011 containing artificial radionuclides, boric acid and hydrazine (and other chemicals)
  3. most significant impacts to the intertidal community occurred along the coast south and proximal to FDNPP which likely reflects predominant local water currents

The changes noted by Horiguchi and colleagues in the intertidal community contrast with the lack of significant changes in benthic organisms along the Japanese coast by Sohtome and colleagues that was summarized here.

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