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| Titel |
Effect of CO2 on the properties and sinking velocity of aggregates of the coccolithophore Emiliania huxleyi |
| VerfasserIn |
A. Biermann, A. Engel |
| 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. 3 ; Nr. 7, no. 3 (2010-03-17), S.1017-1029 |
| Datensatznummer |
250004590
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| Publikation (Nr.) |
 copernicus.org/bg-7-1017-2010.pdf |
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| Zusammenfassung |
| Coccolithophores play an important role in organic matter export due to
their production of the mineral calcite that can act as ballast. Recent
studies indicated that calcification in coccolithophores may be affected by
changes in seawater carbonate chemistry. We investigated the influence of
CO2 on the aggregation and sinking behaviour of the coccolithophore
Emiliania huxleyi (PML B92/11) during a laboratory experiment. The coccolithophores were
grown under low (~180 μatm), medium (~380 μatm), and
high (~750 μatm) CO2 conditions. Aggregation of the cells
was promoted using roller tables. Size and settling velocity of aggregates
were determined during the incubation using video image analysis. Our
results indicate that aggregate properties are sensitive to changes in the
degree of ballasting, as evoked by ocean acidification. Average sinking
velocity was highest for low CO2 aggregates (~1292 m d−1)
that also had the highest particulate inorganic to particulate organic
carbon (PIC/POC) ratio. Lowest PIC/POC ratios and lowest sinking velocity
(~366 m d−1) at comparable sizes were observed for aggregates of
the high CO2 treatment. Aggregates of the high CO2 treatment
showed a 4-fold lower excess density (~4.2×10−4 g cm−3)
when compared to aggregates from the medium and low CO2 treatments
(~1.7 g×10−3 cm−3). We also observed that more aggregates
formed in the high CO2 treatment, and that those aggregates contained
more bacteria than aggregates in the medium and low CO2 treatment. If
applicable to the future ocean, our findings suggest that a CO2 induced
reduction of the calcite content of aggregates could weaken the deep export
of organic matter in the ocean, particularly in areas dominated by
coccolithophores. |
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