Increasing importance of small phytoplankton in a warmer ocean

Xose Anxelu G. Moran*, Ángel López-Urrutia, Alejandra Calvo-Díaz, William K.W. LI

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

376 Scopus citations


The macroecological relationships among marine phytoplankton total cell density, community size structure and temperature have lacked a theoretical explanation. The tiniest members of this planktonic group comprise cyanobacteria and eukaryotic algae smaller than 2 μm in diameter, collectively known as picophytoplankton. We combine here two ecological rules, the temperature-size relationship with the allometric size-scaling of population abundance to explain a remarkably consistent pattern of increasing picophytoplankton biomass with temperature over the -0.6 to 22 °C range in a merged dataset obtained in the eastern and western temperate North Atlantic Ocean across a diverse range of environmental conditions. Our results show that temperature alone was able to explain 73% of the variance in the relative contribution of small cells to total phytoplankton biomass regardless of differences in trophic status or inorganic nutrient loading. Our analysis predicts a gradual shift toward smaller primary producers in a warmer ocean. Because the fate of photosynthesized organic carbon largely depends on phytoplankton size, we anticipate future alterations in the functioning of oceanic ecosystems.

Original languageEnglish (US)
Pages (from-to)1137-1144
Number of pages8
JournalGlobal Change Biology
Issue number3
StatePublished - Jan 1 2010


  • Allometric relationships
  • Cell abundance
  • Cell size
  • North Atlantic
  • Ocean warming
  • Phytoplankton
  • Picophytoplankton
  • Temperature

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • Environmental Science(all)


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