Trophic strategies of unicellular plankton

Subhendu Chakraborty, Lasse Tor Nielsen, Ken Haste Andersen

Research output: Contribution to journalJournal articleResearchpeer-review

358 Downloads (Pure)

Abstract

Unicellular plankton employ trophic strategies ranging from pure photoautotrophs over mixotrophy to obligate heterotrophs (phagotrophs), with cell sizes from 10-8 to 1 μg C. A full understanding of how trophic strategy and cell size depend on resource environment and predation is lacking. To this end, we develop and calibrate a trait-based model for unicellular planktonic organisms characterized by four traits: cell size and investments in phototrophy, nutrient uptake, and phagotrophy. We use the model to predict how optimal trophic strategies depend on cell size under various environmental conditions, including seasonal succession. We identify two mixotrophic strategies: generalist mixotrophs investing in all three investment traits and obligate mixotrophs investing only in phototrophy and phagotrophy. We formulate two conjectures: (1) most cells are limited by organic carbon; however, small unicellulars are colimited by organic carbon and nutrients, and only large photoautotrophs and smaller mixotrophs are nutrient limited; (2) trophic strategy is bottom-up selected by the environment, while optimal size is top-down selected by predation. The focus on cell size and trophic strategies facilitates general insights into the strategies of a broad class of organisms in the size range from micrometers to millimeters that dominate the primary and secondary production of the world's oceans.
Original languageEnglish
JournalAmerican Naturalist
Volume189
Issue number4
Pages (from-to)E77-E90
ISSN0003-0147
DOIs
Publication statusPublished - 2017

Keywords

  • mixotrophy
  • plankton size
  • seasonal succession
  • trait-based model

Fingerprint Dive into the research topics of 'Trophic strategies of unicellular plankton'. Together they form a unique fingerprint.

Cite this