The ecological impacts of the 2011 Great East Japan Earthquake and tsunami and the following recolonization
of the subtidal benthic polychaete community were examined by monthly pre- and post-quake
field surveys that were conducted in Onagawa Bay from 2007 to 2013. Before the tsunami, the species
composition in this benthic community was constant and was dominated by cirratulid and magelonid
polychaetes. The density and biomass of benthic polychaetes drastically decreased after the tsunami, and
the polychaete community fluctuated during the 2 years after the natural disaster. Spionid and capitellid
polychaetes were dominant at this period. In June 2013, the community entered a new constant stage
dominated by maldanids, which is different from the pre-quake community. Ecological impacts due to
chemical pollution were suggested in addition to the tsunami disturbance. These overlapping effects and
physical, chemical and biological factors affected the recovery and recolonization of the polychaete
community after the natural disaster.
© 2015 Elsevier Ltd. All rights reserved.