Carbon isotopic fractionation during a mesocosm bloom experiment dominated by Emiliania huxleyi: Effects of CO2 concentration and primary production

Benthien, A., Zondervan, I., Engel, Anja, Hefter, J., Terbrüggen, A. and Riebesell, Ulf (2007) Carbon isotopic fractionation during a mesocosm bloom experiment dominated by Emiliania huxleyi: Effects of CO2 concentration and primary production Geochimica et Cosmochimica Acta, 71 . pp. 1528-1541. DOI 10.1016/j.gca.2006.12.015.

[img] Text
Carbon isotopic.pdf - Published Version
Restricted to Registered users only

Download (8Mb) | Contact

Supplementary data:

Abstract

We investigated the effect of CO2 and primary production on the carbon isotopic fractionation of alkenones and particulate organic matter (POC) during a natural phytoplankton bloom dominated by the coccolithophore Emiliania huxleyi. In nine semi-closed mesocosms (~11 m3 each), three different CO2 partial pressures (pCO2) in triplicate represented glacial (~180 ppmv CO2), present (~380 ppmv CO2), and year 2100 (~710 ppmv CO2) CO2 conditions. The largest shift in alkenone
isotopic composition (4–5&) occurred during the exponential growth phase, regardless of the CO2 concentration in the
respective treatment. Despite the difference of ~500 ppmv, the influence of pCO2 on isotopic fractionation was marginal
(1–2&). During the stationary phase, E. huxleyi continued to produce alkenones, accumulating cellular concentrations almost four times higher than those of exponentially dividing cells. Our isotope data indicate that, while alkenone production was maintained, the interaction of carbon source and cellular uptake dynamics by E. huxleyi reached a steady state. During stationary phase, we further observed a remarkable increase in the difference between d13C of bulk organic matter and of alkenones spanning 7–12&. We suggest that this phenomenon is caused mainly by a combination of extracellular release of 13C-enriched polysaccharides and subsequent particle aggregation induced by the production of transparent exopolymer particles (TEP).
2007 Elsevier Inc. All rights reserved.

Document Type: Article
Research affiliation: AWI
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography
Kiel University
Refereed: Yes
DOI etc.: 10.1016/j.gca.2006.12.015
ISSN: 0016-7037
Projects: Future Ocean
Date Deposited: 03 Dec 2008 16:51
Last Modified: 08 Sep 2017 12:04
URI: http://eprints.uni-kiel.de/id/eprint/5079

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...