A model of carbon isotopic fractionation and active carbon uptake in phytoplankton

Klaus Keller, Francois M. M. Morel

Research output: Contribution to journalArticlepeer-review

82 Scopus citations


The carbon isotopic fractionation of phytoplankton photosynthesis (ε(p)) has been interpreted by previous authors as inconsistent with active bicarbonate uptake. This interpretation contradicts the results of numerous physiological studies demonstrating significant active bicarbonate uptake in phytoplankton. Using a simple model of cellular regulation of carbon acquisition we show that an upward curvature of ε(p) as a function of the ratio of growth rate to carbon dioxide concentration does not exclude active bicarbonate uptake. Our model describes adequately published carbon isotope data for cyanobacteria, diatoms, and coccolithophores consistent with active bicarbonate uptake.

Original languageEnglish (US)
Pages (from-to)295-298
Number of pages4
JournalMarine Ecology Progress Series
StatePublished - Jun 11 1999

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology


  • Active carbon uptake
  • Bicarbonate
  • Carbon dioxide
  • Carbon isotopic fractionation
  • Model
  • Phytoplankton


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