High resilience of harpacticoid copepods in the landward slope of the Japan Trench against disturbance of the 2011 Tohoku Earthquake

Abstract

AbstractOn 11 March 2011, an earthquake of magnitude Mw 9.0 known as “the 2011 off the Pacific coast of Tohoku Earthquake” occurred off the coast of Miyagi Prefecture. To assess the effect of the earthquake on the deep‐sea ecosystem, we compared harpacticoid assemblages at six stations (100–6000 m water depth) in the landward slope of the Japan Trench off Sanriku in northeastern Japan. We collected samples at the same locations after 4.5 months (2011) and 1.5 yr (2012) after the earthquake. There were no significant differences in depth‐related patterns of harpacticoid assemblages in terms of diversity and community composition between 2011 and 2012. Changing patterns of harpacticoid community composition along water depth in the Sanriku region after the earthquake did not significantly differ from those in the reference region (Kuril region, 500 km away from the Sanriku region, Japan). Our results suggest that the harpacticoid assemblage at the Sanriku region was not affected by the earthquake or that it quickly recovered after the event. Around our study area, large earthquakes have occurred at 500‐yr intervals on average. The observed high resilience of harpacticoid assemblages against the earthquake suggest that benthos with high resilience against disturbance are dominant under a situation in which large disturbances occur every 500 yr or more.