Energy cost and putative benefits of cellular mechanisms modulating buoyancy in aflagellate marine phytoplankton

Michel Lavoie, John A. Raven, Maurice Levasseur

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


Little information is available on the energetics of buoyancy modulation in aflagellate phytoplankton, which comprises the majority of autotrophic cells found in the ocean. Here, we computed for three aflagellate species of marine phytoplankton (Emiliania huxleyi, Thalassiosira pseudonana, and Ethmodiscus rex) the theoretical minimum energy cost as photons absorbed and nitrogen resource required of the key physiological mechanisms (i.e., replacement of quaternary ammonium by dimethyl-sulfoniopropionate, storage of polysaccharides, and cell wall biosynthesis) affecting the cell's vertical movement as a function of nitrogen (N) availability. These energy costs were also normalized to the capacity of each buoyancy mechanism to modulate sinking or rising rates based on Stokes' law. The three physiological mechanisms could act as ballast in the three species tested in conditions of low N availability at a low fraction (<12%) of the total photon energy cost for growth. Cell wall formation in E. huxleyi was the least costly ballast strategy, whereas in T. pseudonana, the photon energy cost of the three ballast strategies was similar. In E. rex, carbohydrate storage and mobilization appear to be energetically cheaper than modulations in organic solute synthesis to achieve vertical migration. This supports the carbohydrate-ballast strategy for vertical migration for this species, but argues against the theory of replacement of low- or high-density organic solutes. This study brings new insights into the energy cost and potential selective advantages of several strategies modulating the buoyancy of aflagellate marine phytoplankton.

Original languageEnglish
Pages (from-to)239-251
Number of pages13
JournalJournal of Phycology: An International Journal of Algal Research
Issue number2
Early online date26 Jan 2016
Publication statusPublished - Apr 2016


  • Aquatic organisms
  • Carbohydrates
  • Carbon
  • Energy metabolism
  • Flagella
  • Ions
  • Minerals
  • Movement
  • Nitrogen
  • Phytoplankton
  • Silicon dioxide
  • Sulfonium compounds
  • Journal article
  • Research support, Non-U.S. Gov't


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