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

Journal article

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.

Authors: McClelland, HLO; Barbarin, N; Beaufort, L; Hermoso, M; Ferretti, P

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Springer Nature
• Journal: Scientific Reports
• Volume: 6
• Issue: 1
• Article number: 34263
• Publication date: 2016-09-28
• Acceptance date: 2016-08-31
• DOI: 10.1038/srep34263
• EISSN: 2045-2322
• Language: English