Calcium isotope fractionation during coccolith formation in Emiliania huxleyi: Independence of growth and calcification rate

Langer, G., Gussone, Nikolaus, Nehrke, G., Riebesell, Ulf, Eisenhauer, Anton and Thoms, Silke (2007) Calcium isotope fractionation during coccolith formation in Emiliania huxleyi: Independence of growth and calcification rate Geochemistry Geophysics Geosystems, 8 (Q05007). DOI 10.1029/2006GC001422.

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[1] Recently, calcium isotope fractionation in the coccolithophore Emiliania huxleyi was shown to exhibit a significant temperature dependency. An important subsequent question in this context is whether the observed fractionation patterns are caused by temperature itself or related growth rate changes. In order to separate growth and calcification rate effects from direct temperature effects, batch culture experiments with the coccolithophore E. huxleyi were conducted under varying light intensities. Despite large changes in cellular growth and calcification rates, calcium isotope fractionation remained constant. Independence of calcium isotope fractionation on growth and calcification was also obtained in two additional sets of experiments in which growth rates changed in response to varying calcium concentration and seawater salinity. These experiments also showed no direct effects of calcium concentration and salinity on calcium isotope fractionation. Values for calcium isotope fractionation of E. huxleyi coccoliths fell within a range of −1.0 to −1.6 (1000 lnα), confirming earlier results. This range is similar to that observed in several foraminiferal species and coccolith oozes, suggesting a rather homogeneous calcium isotopic composition in marine biogenic calcite. Our data further show that the calcium isotope fractionation does not change with changing isotopic composition of seawater. This is a basic requirement for reconstructing the calcium isotopic composition of the ocean over time.

Document Type: Article
Keywords: Marine Biology; Biogeochemistry; Calcium isotopes, Emiliania huxleyi, calcification rate
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography
Refereed: Yes
DOI etc.: 10.1029/2006GC001422
ISSN: 1525-2027
Projects: Future Ocean, EUROCORES
Date Deposited: 29 Apr 2009 10:15
Last Modified: 01 Mar 2018 14:35

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