Evaluation of dinoflagellate grazing on diatom bloom

Research Project

Project/Area Number	23510012
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Environmental dynamic analysis
Research Institution	Ishinomaki Senshu University
Principal Investigator	OTA Takashi 石巻専修大学, 理工学部, 教授 (20364416)
Project Period (FY)	2011-04-28 – 2015-03-31
Project Status	Completed (Fiscal Year 2014)
Budget Amount *help	¥5,850,000 (Direct Cost: ¥4,500,000、Indirect Cost: ¥1,350,000) Fiscal Year 2013: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2012: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2011: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Keywords	珪藻食渦鞭毛虫 / 摂食速度 / 増殖速度 / 食物連鎖 / 群集組成 / スペイン
Outline of Final Research Achievements	The quantitative importance and trophic role of heterotrophic dinoflagellates during spring diatom bloom was studies at a coastal site in Sanriku, Japan. Hetrotrophic dinoflagellates including both thecate and athecate gymnodinoid species often occurred at high abundance composing from 42 to 81% (average 67%) of total microzooplankton biomass and diatom feeders (the species which able to feed on diatom) were dominated heterotrophic dinoflagellate assemblages accounting for 11 to 77%. Daily losses of phytoplankton (mainly diatom) by hetrotrophic dinoflagellate grazing based on in situ experiments were mostly around 5 to 15% of the initial standing stock, or between 10 and 45% of the potential primary production. These estimations partially explained the decrease of diatom standing crops during late bloom stage. This indicates that dinoflagellate herbivory on diatom was highly active and substantial energy was transferred from diatom during bloom.