Journal article

Carbon isotope ratios of coccolith-associated polysaccharides of Emiliania huxleyi as a function of growth rate and CO2 concentration

Elise B Wilkes, Renee BY Lee, Harry LO McClelland, Rosalind EM Rickaby, Ann Pearson



The calcite plates, or coccoliths, of haptophyte algae including Emiliania huxleyi are formed in intracellular vesicles in association with water–soluble acidic polysaccharides. These coccolith–associated polysaccharides (CAPs) are involved in regulating coccolith formation and have been recovered from sediment samples dating back to ∼180 Ma. Paired measurements of the carbon isotopic compositions of CAPs and coccolith calcite have been proposed as a novel paleo–pCO2 barometer, but additional proxy validation and development are still required. Here we present culture results quantifying carbon isotopic offsets between CAPs and other cellular components: bulk organic biomass, alkenones, and ..

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Awarded by National Science Foundation Graduate Research Fellowship

Funding Acknowledgements

This work was supported by a National Science Foundation Graduate Research Fellowship [grant number DGE1144152, to EBW]; the Gordon and Betty Moore Foundation (to AP); and NASA-NAI CAN6 (to AP; PI Roger Summons, MIT). We thank Susie Carter, Katie Mabbott, and Alan Gagnon for assistance with laboratory analyses, Einat Segev for providing starter cultures and culturing advice, John Volkman and Bart van Dongen for editorial handling, and two anonymous reviewers for their thoughtful comments.