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| Titel |
CO2-induced seawater acidification affects physiological performance of the marine diatom Phaeodactylum tricornutum |
| VerfasserIn |
Y. Wu, K. Gao, U. Riebesell |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 9 ; Nr. 7, no. 9 (2010-09-24), S.2915-2923 |
| Datensatznummer |
250004975
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| Publikation (Nr.) |
 copernicus.org/bg-7-2915-2010.pdf |
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| Zusammenfassung |
| CO2/pH perturbation experiments were carried out under two different
pCO2 levels (39.3 and 101.3 Pa) to evaluate effects of CO2-induced
ocean acidification on the marine diatom Phaeodactylum tricornutum. After acclimation (>20
generations) to ambient and elevated CO2 conditions (with corresponding
pH values of 8.15 and 7.80, respectively), growth and photosynthetic carbon
fixation rates of high CO2 grown cells were enhanced by 5% and
12%, respectively, and dark respiration stimulated by 34% compared to
cells grown at ambient CO2. The half saturation constant (Km)
for carbon fixation (dissolved inorganic carbon, DIC) increased by 20%
under the low pH and high CO2 condition, reflecting a decreased
affinity for HCO3– or/and CO2 and down-regulated carbon
concentrating mechanism (CCM). In the high CO2 grown cells, the
electron transport rate from photosystem II (PSII) was photoinhibited to a
greater extent at high levels of photosynthetically active radiation, while
non-photochemical quenching was reduced compared to low CO2 grown
cells. This was probably due to the down-regulation of CCM, which serves as
a sink for excessive energy. The balance between these positive and negative
effects on diatom productivity will be a key factor in determining the net
effect of rising atmospheric CO2 on ocean primary production. |
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