| Co-Investigator(Kenkyū-buntansha) |
ISODA Yutaka Hokkaido University, Graduate School of Fisheries Science, Associate Professor, 大学院・水産科学研究科, 助教授 (10193393)
KUDO Isao Hokkaido University, Graduate School of Fisheries Science, Associate Professor, 大学院・水産科学研究科, 助教授 (00195455)
MARUO Masahiro University of Shiga Prefecture, School of Environmental Science, Assistant Professor, 環境科学部, 助手 (80275156)
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| Budget Amount *help |
¥13,900,000 (Direct Cost: ¥13,900,000)
Fiscal Year 2001: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2000: ¥11,000,000 (Direct Cost: ¥11,000,000)
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| Research Abstract |
We examied zoo-and phytoplankton biomass, bacterial biomass, primary production, bacterial production, meso- and microzooplankton grazing during the period from pre- to post-spring-diatom bloom in Funka Bay, Hokkaido, Japan, to clarify the fate of spring diatom bloom. Diatom bloom started in February at 3 - ℃, lasted by mid-March. During the blooming period, mesozooplankton biomass was alyways low, and consequently its grazing was also quite low level. Microzooplankton increased during the blooming period, but did not graze diatoms Whereas, bacterial production increased during the bloomin period, but its biomass was constant. Using these results, we estimated the carbon budget through food web in the bay. During the blooming period, carbon produced by diatoms was carcely transported to mesozooplankton through grazing food chain due to low mesozooplankton biomass, while microbial loop dominated through bacterial production usingdissolved organic carbon (DOC) from diatoms. On the contrary, after the bloom, two distinct loops existed, i. e. one is dinofragellates to mesozooplankton though regenerated inorganic nutrients by mesozooplankton, while another one is bacteria to protists to mesozooplankton through DOC excreted by mesozooplankton. These results suggest that spring diatom bloom supports indirectly mesozooplankton production through DOC excreted by diatoms, while after the bloom nutrients and DOC regenerated by mesozooplankton supported dinofragellate production and subsequently mesozooplankton themselves.
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