日本地球惑星科学連合2015年大会

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セッション記号 M (領域外・複数領域) » M-IS ジョイント

[M-IS33] 2011年巨大地震・津波以後の東北沖海洋科学

2015年5月26日(火) 11:00 〜 12:45 102B (1F)

コンビーナ:*宇佐見 和子(産業技術総合研究所地質情報研究部門)、池原 研(産業技術総合研究所地質情報研究部門)、伊藤 喜宏(京都大学防災研究所)、豊福 高志(独立行政法人海洋研究開発機構)、座長:池原 研(産業技術総合研究所地質情報研究部門)

12:33 〜 12:36

[MIS33-P07] 2011年東北地方太平洋沖地震後の上部漸深海帯底生生物群集

ポスター講演3分口頭発表枠

*野牧 秀隆1望月 智弘2北橋 倫3布浦 拓郎1新井 和乃4豊福 高志1菅 寿美1脇田 昌英1田中 源吾5滋野 修一1田角 栄二1藤倉 克則1渡邉 修一1 (1.海洋研究開発機構、2.東京工業大学、3.東京大学、4.埼玉大学、5.熊本大学)

キーワード:メイオベントス, 底生微生物, 2011年東北地方太平洋沖地震, 堆積物

We examined the effects of mass sedimentation events caused by the 2011 off the Pacific coast of Tohoku earthquake on abundances and vertical distributions of prokaryotes and metazoan meiofauna in sediments, using sediment cores collected from eight bathyal stations off Tohoku 1 and 2.5 years after the M9.0 earthquake. Event deposits of 1 to 7 cm thick were observed at the topmost part of the sediment cores at all sampling stations. At some stations, prokaryotic cell abundances were lower in the surface event-deposit layers compared to those in deeper sediments. These variations were explained by environmental parameters such as a sorting factor and mean grain size, suggesting that turbidite sedimentation affected prokaryotic cell abundances. Nematodes had anomalously higher subsurface abundances at the stations where subsurface peak prokaryotic cell numbers were observed. Although there are no corresponding data before the earthquake from the same sites, it is likely that the subsurface peaks in prokaryotic cell numbers and meiofaunal density resulted from the sedimentation events. The effects of sedimentation events on the organisms were observed 2.5 years after the earthquake, indicating that episodic sedimentation events on scales of several centimeters have a large effect on small organisms inhabiting sediments.