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Calcification response of a key phytoplankton family to millennial-scale environmental change

Published version
Peer-reviewed

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Authors

McClelland, HLO 
Barbarin, N 
Beaufort, L 
Hermoso, M 
Ferretti, P 

Abstract

Coccolithophores are single-celled photosynthesizing marine algae, responsible for half of the calcification in the surface ocean, and exert a strong influence on the distribution of carbon among global reservoirs, and thus Earth’s climate. Calcification in the surface ocean decreases the buffering capacity of seawater for CO2, whilst photosynthetic carbon fixation has the opposite effect. Experiments in culture have suggested that coccolithophore calcification decreases under high CO2 concentrations ([CO2(aq)]) constituting a negative feedback. However, the extent to which these results are representative of natural populations, and of the response over more than a few hundred generations is unclear. Here we describe and apply a novel rationale for size-normalizing the mass of the calcite plates produced by the most abundant family of coccolithophores, the Noëlaerhabdaceae. On average, ancient populations subjected to coupled gradual increases in [CO2(aq)] and temperature over a few million generations in a natural environment become relatively more highly calcified, implying a positive climatic feedback. We hypothesize that this is the result of selection manifest in natural populations over millennial timescales, so has necessarily eluded laboratory experiments.

Description

Keywords

37 Earth Sciences, 31 Biological Sciences, 3103 Ecology, 14 Life Below Water

Journal Title

Scientific Reports

Conference Name

Journal ISSN

2045-2322
2045-2322

Volume Title

6

Publisher

Nature Publishing Group
Sponsorship
European Research Council (267931)
HLOM was funded by PhD studentship NE/I019522/1 in association with UKOARP. REMR acknowledges NERC grant NE/H017119/1 and ERC grant SP2-GA-2008-200915. LB is grateful for financial support from EU Seventh Framework program Past4Future and from the Agence Nationale de la Recherche under project ANR-12-B06-0007 (CALHIS). PF was funded by Marie-Curie Reintegration grant (PERG-GA-2010-272134 - MILLEVARIABILI), funded by the EU PNRA 2013/AZ2.06 and GEOSMART, funded by the Italian National Antarctic Research Programme.