标题：Changes in Abalone and Sea Urchin Populations in Rocky Reef Ecosystems on the Sanriku Coast Damaged by the Massive Tsunami and Other Environmental Changes Associated with the Great East Japan Earthquake in 2011
摘要：Changes in populations of the abalone Haliotis discus hannai and sea urchin Strongylocentrotus nudus following the tsunami and other events associated with the Great East Japan Earthquake which occurred on March 11, 2011, are compared between two sites, Tomarihama on the Oshika Peninsula and Nagane in Otsuchi Bay on the Sanriku Coast in northeastern Japan. As Tomarihama faces directly onto the Pacific Ocean, effects of the tsunami are likely to be heavier than at Nagane located near the mouth of Otsuchi Bay. At Tomarihama, both adult and juvenile abalone were apparently affected by the tsunami disturbance, while at Nagane in Otsuchi Bay, juvenile abalone <4 cm SL appeared to be more seriously affected by the tsunami than adults. Sea urchin densities decreased considerably at both Tomarihama and Nagane, indicating that sea urchins were more severely impacted by the event compared with abalone. The sea urchin density remained low for two years after the event at Tomarihama, but recovered to almost the same level as before the tsunami within six months from the event at Nagane. The results of the present study suggest that benthic organisms which attach weakly to bottom substrates were more seriously impacted than strongly attached organisms. Organisms inhabiting exposed areas suffer more effects than those inhabiting perennial kelp forests, where the current velocity of the tsunami may be attenuated by the presence of the algal canopy. Although the damaged populations have started recovering and/or adapting to the new environment, the speed and process of change differ between the organisms and areas.
