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| Titel |
Significance of archaeal nitrification in hypoxic waters of the Baltic Sea |
| VerfasserIn |
C. Berg, V. Vandieken, B. Thamdrup, K. Jürgens |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250063938
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| Zusammenfassung |
| Marine oxygen deficient areas are sites of important microbially mediated transformations
within the nitrogen cycle. In the Baltic Sea, suboxic waters (oxygen below 5 μmol L-1) are
considered to be a major nitrification zone within the water column. Recent evidence
indicates that Archaea and not Bacteria are here the major ammonium oxidizers. In a
Baltic Sea pelagic redoxcline, the crenarchaeotal subcluster GD2 which is related to
the first cultivated ammonia-oxidizing crenarchaeote Candidatus Nitrosopumilus
maritimus occurs in high abundance. However, little is known about its function and
importance for the nitrogen and carbon cycles in oxygen minimum zones of the Baltic
Sea.
To approach this question, we sampled pelagic redoxclines in the Baltic Sea and
determined the rates of nitrification and light-independent, inorganic carbon fixation via 15N
and 14C isotope incubations, and quantified the abundance of putative ammonia-oxidizing
Crenarchaeota by catalyzed reporter deposition fluorescence in situ hybridization
(CARD-FISH).
Nitrification was detectable throughout the suboxic zone with maxima of 122-131 nmol
L-1 d-1 in layers with 1.8-7.1 μmol oxygen L-1 and ammonium below 0.2 μmol L-1.
However, a nitrification potential was detected even in the upper anoxic, sulfidic zone.
Crenarchaeotal abundance correlated strongly with nitrification rates and accounted for up to
24% of total prokaryotic cells. In contrast, the CO2 fixation in the suboxic zone was with
1.6-19.6 nmol L-1 d-1 rather low when compared to the subjacent anoxic, sulfidic
waters.
Our study indicates that ammonia oxidation in the suboxic zone of the Baltic Sea is
mainly driven by Crenarchaeota. Their occurrence also in the anoxic, sulfidic water masses
and the maintained nitrification potential point to special adaptations in this habitat with a
potentially reduced sensitivity against hydrogen sulfide. |
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