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Distinguishing between the effects of ocean acidification and ocean carbonation in the coccolithophore Emiliania huxleyi


Bach, LT and Riebesell, U and Schulz, KG, Distinguishing between the effects of ocean acidification and ocean carbonation in the coccolithophore Emiliania huxleyi, Limnology and Oceanography, 56, (6) pp. 2040-2050. ISSN 0024-3590 (2011) [Refereed Article]

Copyright Statement

Copyright 2011, by the Association for the Sciences of Limnology and Oceanography, Inc.

DOI: doi:10.4319/lo.2011.56.6.2040


The coccolithophore Emiliania huxleyi was cultured under a broad range of carbonate chemistry conditions to distinguish the effects of individual carbonate system parameters on growth, primary production, and calcification. In the first experiment, alkalinity was kept constant and the fugacity of CO2 (fCO2) varied from 2 to 600 Pa (1 Pa ≈ 10 ľatm). In the second experiment, pH was kept constant (pHfree = 8) with fCO2 varying from 4 to 370 Pa. Results of the constant‐alkalinity approach revealed physiological optima for growth, calcification, and organic carbon production at fCO2 values of ~ 20 Pa, ~ 40 Pa, and ~ 80 Pa, respectively. Comparing this with the constant‐pH approach showed that growth and organic carbon production increased similarly from low to intermediate CO2 levels but started to diverge towards higher CO2 levels. In the high CO2 range, growth rates and organic carbon production decreased steadily with declining pH at constant alkalinity while remaining consistently higher at constant pH. This suggests that growth and organic carbon production rates are directly related to CO2 at low (sub‐saturating) concentrations, whereas towards higher CO2 levels they are adversely affected by the associated decrease in pH. A pH dependence at high fCO2 is also indicated for calcification rates, while the key carbonate system parameter determining calcification at low fCO2 remains unclear. These results imply that key metabolic processes in coccolithophores have their optima at different carbonate chemistry conditions and are influenced by different parameters of the carbonate system at both sides of the optimum.

Item Details

Item Type:Refereed Article
Keywords:phytoplankton, ocean acidification, coccolithophore, calcification, carbonate chemistry
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical oceanography
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Bach, LT (Dr Lennart Bach)
ID Code:134499
Year Published:2011
Web of Science® Times Cited:77
Deposited By:Ecology and Biodiversity
Deposited On:2019-08-15
Last Modified:2019-09-13

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