Effects of diurnal vertical migration and turbulent mixing on formation of harmful flagellate blooms

2015 Fiscal Year Final Research Report

• Project/Area Number: 25340024
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Environmental dynamic analysis
• Research Institution: Japan Fisheries Research and Education Agency
• Principal Investigator: ONITSUKA Goh 国立研究開発法人水産総合研究センター, 瀬戸内海区水産研究所, グループ長 (40399647)
• Co-Investigator(Kenkyū-buntansha): YOSHIKAWA Yutaka 京都大学, 理学研究科, 准教授 (40346854) ; SHIKATA Tomoyuki 国立研究開発法人・水産総合研究センター, 瀬戸内海区水産研究所, 研究員 (40603048)
• Research Collaborator: YUFU Kei 九州大学, 応用力学研究所, 技術職員
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 有害鞭毛藻 / 極大層 / 鉛直移動 / 混合 / LES

Outline of Final Research Achievements

Laboratory experiments, field observations and numerical experiments were conducted to investigate the effects of diurnal vertical migration and turbulent mixing on formation of harmful flagellate blooms. The effects of salinity on diurnal vertical migration behavior of flagellate were examined in the laboratory experiments. The results suggest that halocline could change the accumulation depth. In the continuous day and night field observations, diurnal vertical migration of flagellates, which attains to nutrient replete subsurface layer, is important for maintenance of their populations in condition with low turbulence relative to their swimming speeds. Experiments using numerical model with turbulent mixing were conducted to investigate behavior of particles simulating flagellate. The results indicated that the balance between swimming speed and oceanographic conditions influence duration of surface accumulation of particles.

Free Research Field

沿岸海洋学