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| Titel |
The role of ocean acidification in Emiliania huxleyi coccolith thinning in the Mediterranean Sea |
| VerfasserIn |
K. J. S. Meier, L. Beaufort, S. Heussner, P. Ziveri |
| 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 ; 11, no. 10 ; Nr. 11, no. 10 (2014-05-28), S.2857-2869 |
| Datensatznummer |
250117427
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| Publikation (Nr.) |
 copernicus.org/bg-11-2857-2014.pdf |
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| Zusammenfassung |
| Ocean acidification is a result of the uptake of anthropogenic CO2 from
the atmosphere into the ocean and has been identified as a major
environmental and economic threat. The release of several thousands of
petagrams of carbon over a few hundred years will have an overwhelming effect
on surface ocean carbon reservoirs. The recorded and anticipated changes in
seawater carbonate chemistry will presumably affect global oceanic carbonate
production. Coccolithophores as the primary calcifying phytoplankton group,
and especially Emiliania huxleyi as the most abundant species have
shown a reduction of calcification at increased CO2 concentrations for
the majority of strains tested in culture experiments. A reduction of
calcification is associated with a decrease in coccolith weight. However, the
effect in monoclonal cultures is relatively small compared to the strong
variability displayed in natural E. huxleyi communities, as these
are a mix of genetically and sometimes morphologically distinct types.
Average coccolith weight is likely influenced by the variability in seawater
carbonate chemistry in different parts of the world's oceans and on
glacial/interglacial time scales due to both physiological effects and
morphotype selectivity. An effect of the ongoing ocean acidification on
E. huxleyi calcification has so far not been documented in situ.
Here, we analyze E. huxleyi coccolith weight from the NW
Mediterranean Sea in a 12-year sediment trap series, and surface sediment and
sediment core samples using an automated recognition and analyzing software.
Our findings clearly show (1) a continuous decrease in the average coccolith
weight of E. huxleyi from 1993 to 2005, reaching levels below
pre-industrial (Holocene) and industrial (20th century) values recorded in
the sedimentary record and (2) seasonal variability in coccolith weight that
is linked to the coccolithophore productivity. The observed long-term
decrease in coccolith weight is most likely a result of the changes in the
surface ocean carbonate system. Our results provide the first indications of
an in situ impact of ocean acidification on coccolithophore weight in a
natural E. huxleyi population, even in the highly alkaline
Mediterranean Sea. |
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