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Marine Biology

, Volume 39, Issue 2, pp 111–120 | Cite as

Nitrogen assimilation by phytoplankton and other microorganisms in the surface waters of the central North Pacific Ocean

  • R. W. Eppley
  • J. H. Sharp
  • E. H. Renger
  • M. J. Perry
  • W. G. Harrison
Article

Abstract

Assimilation rates of 15N-labelled ammonium, urea, and nitrate by plankton in the upper euphotic zone were measured in 2 summer, 2 winter, and 1 spring cruise in the central North Pacific Ocean. Average rates of ammonium plus urea assimilation could not be determined precisely, but were estimated to be 7 to 25 μg-at. N m-3 day-1. Indirect evidence suggested that non-photosynthetic microorganisms contributed to these rates. Nitrate assimilation was negligible in the upper waters considered in this report (above the chlorophyll maximum and the nutricline). Potential, nitrate-saturated rates were in the range 1 to 8 μg-at. N m-3 day-1. Seasonal comparison showed lowest rates of both carbon and nitrogen assimilation rates per chlorophyll a in winter.

Keywords

Nitrate Chlorophyll Urea Phytoplankton Assimilation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 1977

Authors and Affiliations

  • R. W. Eppley
    • 1
  • J. H. Sharp
    • 1
  • E. H. Renger
    • 1
  • M. J. Perry
    • 1
  • W. G. Harrison
    • 1
  1. 1.Institute of Marine ResourcesUniversity of CaliforniaLa JollaUSA

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