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| Titel |
Effects of CO2 and iron availability on rbcL gene expression in Bering Sea diatoms |
| VerfasserIn |
H. Endo, K. Sugie, T. Yoshimura, K. Suzuki |
| 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 ; 12, no. 7 ; Nr. 12, no. 7 (2015-04-15), S.2247-2259 |
| Datensatznummer |
250117899
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| Publikation (Nr.) |
 copernicus.org/bg-12-2247-2015.pdf |
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| Zusammenfassung |
| Iron (Fe) can limit phytoplankton productivity in approximately 40% of
the global ocean, including in high-nutrient, low-chlorophyll (HNLC) waters.
However, there is little information available on the impact of
CO2-induced seawater acidification on natural phytoplankton assemblages
in HNLC regions. We therefore conducted an on-deck experiment manipulating
CO2 and Fe using Fe-deficient Bering Sea water during the summer of
2009. The concentrations of CO2 in the incubation bottles were set at
380 and 600 ppm in the non-Fe-added (control) bottles and 180, 380, 600, and
1000 ppm in the Fe-added bottles. The phytoplankton assemblages were
primarily composed of diatoms followed by haptophytes in all incubation
bottles as estimated by pigment signatures throughout the 5-day (control) or
6-day (Fe-added treatment) incubation period. At the end of incubation, the
relative contribution of diatoms to chlorophyll a biomass was significantly
higher in the 380 ppm CO2 treatment than in the 600 ppm treatment in
the controls, whereas minimal changes were found in the Fe-added treatments.
These results indicate that, under Fe-deficient conditions, the growth of
diatoms could be negatively affected by the increase in CO2
availability. To further support this finding, we estimated the expression
and phylogeny of rbcL (which encodes the large subunit of RuBisCO) mRNA in
diatoms by quantitative reverse transcription polymerase chain reaction (PCR) and clone library
techniques, respectively. Interestingly, regardless of Fe availability, the
transcript abundance of rbcL decreased in the high CO2 treatments (600 and
1000 ppm). The present study suggests that the projected future increase in
seawater pCO2 could reduce the RuBisCO transcription of diatoms,
resulting in a decrease in primary productivity and a shift in the food web
structure of the Bering Sea. |
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