Frontiers in Marine Science (Dec 2020)

The Possession of Coccoliths Fails to Deter Microzooplankton Grazers

  • Kyle M. J. Mayers,
  • Kyle M. J. Mayers,
  • Alex J. Poulton,
  • Kay Bidle,
  • Kimberlee Thamatrakoln,
  • Brittany Schieler,
  • Sarah L. C. Giering,
  • Seona R. Wells,
  • Glen A. Tarran,
  • Dan Mayor,
  • Matthew Johnson,
  • Ulf Riebesell,
  • Aud Larsen,
  • Assaf Vardi,
  • Elizabeth L. Harvey

DOI
https://doi.org/10.3389/fmars.2020.569896
Journal volume & issue
Vol. 7

Abstract

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Phytoplankton play a central role in the regulation of global carbon and nutrient cycles, forming the basis of the marine food webs. A group of biogeochemically important phytoplankton, the coccolithophores, produce calcium carbonate scales that have been hypothesized to deter or reduce grazing by microzooplankton. Here, a meta-analysis of mesocosm-based experiments demonstrates that calcification of the cosmopolitan coccolithophore, Emiliania huxleyi, fails to deter microzooplankton grazing. The median grazing to growth ratio for E. huxleyi (0.56 ± 0.40) was not significantly different among non-calcified nano- or picoeukaryotes (0.71 ± 0.31 and 0.55 ± 0.34, respectively). Additionally, the environmental concentration of E. huxleyi did not drive preferential grazing of non-calcified groups. These results strongly suggest that the possession of coccoliths does not provide E. huxleyi effective protection from microzooplankton grazing. Such indiscriminate consumption has implications for the dissolution and fate of CaCO3 in the ocean, and the evolution of coccoliths.

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