Response of lower trophic organisms to nutrient input and effects on carbon budget : a mesocosm experiment

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Author(s)

Abstract

The roles of heterotrophic organisms (microzooplankton, mesozooplankton, bacteria and heterotrophic nanoflagellates) were examined during a nutrient enrichment experiment using a mesocosm in Saanich Inlet, British Columbia, Canada. Grazing rates of microzooplankton, copepods, and <i>Noctiluca scintillans</i> were respectively estimated by the dilution method, from the egg production, and the apparent growth rate. The primary production increased by about 11 times during the initial 3 days, and the grazing rate by zooplankton also increased by 7.4 times. The primary production exceeded the grazing rate during the initial 5 days, after that, almost balanced rates were observed. Biomass peaks of bacteria and HNFs (heterotrophic nanoflagellates) were observed after the decline of the phytoplankton bloom. Bacterial production and HNF bacterivory gradually increased from the beginning to the end of the experiment. Microzooplankton consistently removed about half of the primary production. The contribution of microzooplankton to grazing was largest during the initial 7 days. Heterotrophic dinoflagellates were the most dominant component of the microzooplankton, but oligotrich ciliates showed the fastest growth response to phytoplankton production. <i>Noctiluca scintillans</i> became an important grazer after the bloom. Overall, the contribution of microzooplankton grazing was the largest of the processes through which phytoplankton were lost. Cell sinking was a minor component contributing to loss of phytoplankton. Thus, oligotrich ciliates and heterotrophic dinoflagellates were the most plausible organisms contributing to the steady state of phytoplankton concentrations.

Journal

  • Plankton and Benthos Research

    Plankton and Benthos Research 5(4), 144-155, 2010-11-01

    The Plankton Society of Japan, The Japanese Association of Benthology

References:  68

Codes

  • NII Article ID (NAID)
    10027122064
  • NII NACSIS-CAT ID (NCID)
    AA12130745
  • Text Lang
    ENG
  • Article Type
    ART
  • ISSN
    18808247
  • NDL Article ID
    10899796
  • NDL Source Classification
    ZR1(科学技術--生物学)
  • NDL Call No.
    Z54-J424
  • Data Source
    CJP  NDL  J-STAGE 
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