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| Titel |
Enhancement of photosynthetic carbon assimilation efficiency by phytoplankton in the future coastal ocean |
| VerfasserIn |
J.-H. Kim, K. Y. Kim, E. J. Kang, K. Lee, J.-M. Kim, K.-T. Park, K. Shin, B. Hyun, H. J. Jeong |
| 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 ; 10, no. 11 ; Nr. 10, no. 11 (2013-11-21), S.7525-7535 |
| Datensatznummer |
250085431
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| Publikation (Nr.) |
 copernicus.org/bg-10-7525-2013.pdf |
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| Zusammenfassung |
| A mesocosm experiment was conducted to evaluate the influence of
photosynthetic performance on the energetic balance of coastal
phytoplankton, in relation to community production and autotrophic
phytoplankton biomass in future coastal oceans. Natural phytoplankton
assemblages were incubated in field mesocosms under ambient condition
(control: ca. 400 μatm CO2 and ambient temperature), and two
sets of potential future ocean conditions (acidification: ca. 900 μatm
CO2 and ambient temperature; greenhouse: ca. 900 μatm CO2
and 3 °C warmer). The photosynthetic performances were estimated by in
vivo fluorometry (effective quantum yield (ΦPSII), steady-state
light response curves (LCs)) and in situ incorporation of 14C
(photosynthesis-irradiance curves). The ΦPSII and rETRm,LC
(relative maximum electron transport rate) clearly reduced under
acidification, in particular, when phytoplankton were exposed to high light
levels. However, PBmax (maximum photosynthetic rate) was the same
in the ambient and acidification conditions. Thus, phytoplankton utilized
less light under acidification condition, but could still assimilate a
similar amount of carbon compared to the ambient condition. The
PBmax and α (photosynthetic efficiency) under greenhouse
condition were significantly higher than those under ambient condition
without any difference in ΦPSII, rETRm,LC and α,LC
(electron transport efficiency) between the treatments. Therefore,
phytoplankton utilized the same amount of light under greenhouse condition,
but could assimilate more carbon than under ambient condition. As a result,
Chl a normalized primary production was higher in greenhouse than in other
conditions. Nevertheless, the community production did not change between
the experimental treatments. The main reason for the lack of a change in
primary production under future climate conditions is the control of
autotrophic phytoplankton biomass by grazing. Consequently, acidification
and greenhouse environments have a potential to increase growth and primary
production of phytoplankton by enhancing inorganic carbon assimilation
efficiency when top-down regulation is negligible. |
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