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| Titel |
Photosynthetic responses of Emiliania huxleyi to UV radiation and elevated temperature: roles of calcified coccoliths |
| VerfasserIn |
K. Xu, K. Gao, V. E. Villafañe, E. W. Helbling |
| 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 ; 8, no. 6 ; Nr. 8, no. 6 (2011-06-06), S.1441-1452 |
| Datensatznummer |
250005947
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| Publikation (Nr.) |
 copernicus.org/bg-8-1441-2011.pdf |
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| Zusammenfassung |
| Changes in calcification of coccolithophores may affect their photosynthetic
responses to both, ultraviolet radiation (UVR, 280–400 nm) and temperature.
We operated semi-continuous cultures of Emiliania huxleyi (strain CS-369) at reduced (0.1 mM,
LCa) and ambient (10 mM, HCa) Ca2+ concentrations and, after 148
generations, we exposed cells to six radiation treatments (>280, >295,
>305, >320, >350 and >395 nm by using Schott filters) and two
temperatures (20 and 25 °C) to examine photosynthesis and calcification
responses. Overall, our study demonstrated that: (1) decreased calcification
resulted in a down regulation of photoprotective mechanisms (i.e., as
estimated via non-photochemical quenching, NPQ), pigments contents and
photosynthetic carbon fixation; (2) calcification (C) and photosynthesis
(P) (as well as their ratio) have different responses related to UVR with
cells grown under the high Ca2+ concentration being more resistant to
UVR than those grown under the low Ca2+ level; (3) elevated temperature
increased photosynthesis and calcification of E. huxleyi grown at high Ca2+
concentrations whereas decreased both processes in low Ca2+ grown
cells. Therefore, a decrease in calcification rates in E. huxleyi is expected to
decrease photosynthesis rates, resulting in a negative feedback that further
reduces calcification. |
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