Ecological studies on sulfur bacteria in a hypoxic inner bay with special emphasis on their trophic fate

2015 Fiscal Year Final Research Report

• Project/Area Number: 25292114
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Aquatic bioproduction science
• Research Institution: Nagasaki University
• Principal Investigator: WADA Minoru 長崎大学, 水産・環境科学総合研究科(水産), 教授 (70292860)
• Co-Investigator(Kenkyū-buntansha): KONDO Ryuji 福井県立大学, 海洋生物資源学部, 教授 (30244528) ; UMEZAWA Yu 長崎大学, 水産・環境科学総合研究科(水産), 准教授 (50442538) ; NISHIHARA Gregory Naoki 長崎大学, 水産・環境科学総合研究科(環シナ), 准教授 (40508321) ; SHIMANAGA Motohiro 熊本大学, 沿岸域環境科学教育研究センター, 准教授 (70345057)
• Co-Investigator(Renkei-kenkyūsha): SUNAMURA Michinari 東京大学, 大学院理学系研究科, 助教 (90360867)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 貧酸素水塊 / 閉鎖性内湾 / 微生物群集

Outline of Final Research Achievements

During 2013 through 2015, hypoxia in the center of Omura Bay has consistently developed in summer (July through September). Although the extent to which microbial mat composed of sulfur bacteria developed on the bottom sediment varied significantly year to year, Proteobacteria contributed to the majority of the bacterial community composition in the upper surface layer of the sediment. Bacterial groups involved in sulfur cycle such as Desulfobacterales and Thiotrichales were significantly dominant throughout the hypoxic period. Changes in abundance and metabolic activities of both sulfur reducing and sulfur oxidizing bacteria seemed to be driven by the extent of bottom hypoxia. Besides, grazing on bacteria by anaerobic heterotrophic nanoflagellates as well as low-oxygen tolerant benthic nematodes may have exerted fundamental top-down control over the sediment bacterial population during the period of hypoxia in Omura Bay.

Free Research Field

海洋微生物生態学