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Studies on environmental regulation mechanisms of picophytoplankton growth in the aquatic ecosystem

Research Project

Project/Area Number 61440001
Research Category

Grant-in-Aid for General Scientific Research (A)

Allocation TypeSingle-year Grants
Research Field 生態学
Research InstitutionThe University of Tokyo

Principal Investigator

TAKAHASHI Masayuki  Botany Dept. Univ. Tokyo Ass. Prof., 理学部, 助教授 (50111357)

Project Period (FY) 1986 – 1989
Project Status Completed (Fiscal Year 1989)
Budget Amount *help
¥21,000,000 (Direct Cost: ¥21,000,000)
Fiscal Year 1989: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1988: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1987: ¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 1986: ¥11,000,000 (Direct Cost: ¥11,000,000)
Keywordsaquatic ecosystem / picophytoplankton / cyanobacteria / grazing pressure / growth rate / environmental regulation / 藍藻 / 捕食作用 / 諏訪湖 / 模相湾
Research Abstract

Details of picophytoplankton were not clear other than their cell sizes of less than 2um at the start of this research. Then unicellular cyanobacteria, being known to be one of abundant picophytoplankton in the sea and being recognized easily under a fluorescent microscope, were focused attention. The unicellular cyanobacteria were observed their wide distributions covering from pelagic to neritic ocean and lakes, and showed a rather small spatial and temporal variations in biomass such as about 2 orders of magnitudes compared to a large variation range of such as 5 orders of magnitudes in chlorophyll a__- (total phytoplankton biomass). The cyanobacteria become an exclusive dominant group in pelagic waters where phytoplankton population is small in size.
In situ growth rates of the cyanobacteria determined by three different methods in oligotrophic pelagic ocean equally gave about one division per day, which was equivalent to the rate obtained by unicellular cultures of cyanobacteria un … More der suitable growth conditions in the laboratory. This high in situ rate was also supported by active in situ photosynthetic rates determined by ^<14>C and ^<13>C tracer techniques. From time series experiments of division frequency of the cyanobacterial cells under natural conditions, cell division occurred throughout a day with showing extensive cell division during a few hours around dusk.
Actual biomass changes of the cyanobacteria in the water were observed a rapid increase between dusk and dawn, and a decrease between dawn and dusk. The decrease was evaluated mainly due to grazing by protozoa of flagellates and ciliates.
From the present study it has become clear that increased biomass of the cyanobacteria by active growth has utilized by grazing of protozoa. The biomass of the cyanobacteria was then maintained at a constant steady level which seem to be mainly regulated by grazing pressure. The unicellular cyanobacteria are considered be one of active metabolid agents in pelagic ecosystems. Less

Report

(5 results)
  • 1989 Annual Research Report   Final Research Report Summary
  • 1988 Annual Research Report
  • 1987 Annual Research Report
  • 1986 Annual Research Report
  • Research Products

    (16 results)

All Other

All Publications (16 results)

  • [Publications] 高橋正征: "低次生産過程と生産力" 21世紀の漁業と水産海洋研究(水産海洋研究会編). 51-58 (1988)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Takahashi,M.,S.Ichimura,M.Kishino and Nokami: "Shade and chromatic adaptation of phytoplankton photosynthesis in a thermally stratified sea" Marine Biology. 100. 401-409 (1989)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Kudoh,S.,J.Kanda and M.Takahashi,: "Specific growth rates and grazing mortality of chroococcoid cyanobacteria(Synechococcus spp.)in pelagic surface waters in the sea" Limnolgy and Oceanography(投稿中).

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Ikeya,T.,K.Ohki,M.Takahashi and Y.Fujita: "Photosynthetic characteristics of a pecoplanktonic alga,Synechococcus sp.,in the sea" (投稿準備中).

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Takahashi,M.and H.Toda: "Zooplankton feeding on picophytoplankton in pelagic ocean" (投稿準備中).

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Takahashi, M.: "Production processes and productivity of primary production" Studies on Fisheries Oceanography (ed. Japanese Society of Fisheries Oceanography). 51-58 (1988)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Takahashi, M., S. Ichimura, M. Kishino and N. Okami: "Shade and chromatic adaptation of phytoplankton photosynthesis in a thermally stratified sea" Marine Biology. 100. 401-409 (1989)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Kudoh, S., J. Kanda and M. Takahashi: "Specific growth rates and grazing mortality of chroococcoid syanobacteria (Synechococcus spp.) in pelagic surface waters in the sea" Journal of the Experimental Marine Biology and Ecology.

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Ikeya, T., K. Ohki, M. Takahashi and Y. Fujita: "Photosynthetic characteristics of a picoplanktonic alga, Synechococcus sp., in the sea"

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Takahashi, M. and H. Toda: "Zooplankton feeding on picophytoplankton in pelagic ocean"

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1989 Final Research Report Summary
  • [Publications] Kudoh,S.,J.Kanda and M.Takahashi: "Specific growth rates and grazing mortality of chroococcoid cyanobacteria(Synechococcus spp.)in pelagic surface waters in the sea" Limnology and Oceanography.

    • Related Report
      1989 Annual Research Report
  • [Publications] Ikeya,T.,K.Ohki,M,Takahashi and Y.Fujita: "Photosynthetic characteristics of a picoplanktonic alga,Synechococcus sp.in the sea"

    • Related Report
      1989 Annual Research Report
  • [Publications] Takahashi,M.and H.Toda: "Zooplankton feeding on picophytoplankton in pelagic ocean"

    • Related Report
      1989 Annual Research Report
  • [Publications] 高橋正征: 21世紀の漁業と水産海洋研究 水産海洋研究会 編. 51-58 (1988)

    • Related Report
      1988 Annual Research Report
  • [Publications] M.Takahashi;S.Ichimura;M.Kishino;N.Okami: Marine Biology.

    • Related Report
      1988 Annual Research Report
  • [Publications] M. Takahashi; S. Ichimura; M. Kishino; N. Okami: Limnology and Oceanography. (1988)

    • Related Report
      1987 Annual Research Report

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Published: 1987-03-31   Modified: 2016-04-21  

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