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Abstract
Marine algae are instrumental in carbon cycling and atmospheric carbon dioxide (CO2) regulation. One group, coccolithophores, uses carbon to photosynthesize and to calcify, covering their cells with chalk platelets (coccoliths). How ocean acidification influences coccolithophore calcification is strongly debated, and the effects of carbonate chemistry changes in the geological past are poorly understood. This paper relates degree of coccolith calcification to cellular calcification, and presents the first records of size-normalized coccolith thickness spanning the last 14 Myr from tropical oceans. Degree of calcification was highest in the low-pH, high-CO2 Miocene ocean, but decreased significantly between 6 and 4 Myr ago. Based on this and concurrent trends in a new alkenone ɛp record, we propose that decreasing CO2 partly drove the observed trend via reduced cellular bicarbonate allocation to calcification. This trend reversed in the late Pleistocene despite low CO2, suggesting an additional regulator of calcification such as alkalinity.
Department
Earth Sciences
Publication Date
1-14-2016
Journal Title
Nature Communications
Publisher
Springer Nature
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
Bolton, C.T., Hernandez-Sanchez M.T., Fuertes, M.-A., Gonzales-Lemos, S., Abrevaya, L., Mendez-Vicente, A., Flores, J.-A., Probert, I., Giosan, L., Johnson, J.E., and Stoll, H.M., 2016. Decrease in coccolithophore calcification and CO2 since the middle Miocene. Nature Communications. 7:10284 doi: 10.1038/ncomms10284 (2016). http://www.nature.com/ncomms/2016/160114/ncomms10284/pdf/ncomms10284.pdf
Comments
This is an article published by Springer Nature in Nature Communications in 2016, available online: https://dx.doi.org/10.1038/ncomms10284