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| Titel |
Experimental evidence for foraminiferal calcification under anoxia |
| VerfasserIn |
M. P. Nardelli, C. Barras, E. Metzger, A. Mouret, H. L. Filipsson, F. Jorissen, E. Geslin |
| 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. 14 ; Nr. 11, no. 14 (2014-07-31), S.4029-4038 |
| Datensatznummer |
250117532
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| Publikation (Nr.) |
 copernicus.org/bg-11-4029-2014.pdf |
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| Zusammenfassung |
| Benthic foraminiferal tests
are widely used for paleoceanographic reconstructions from a range of
different environments with varying dissolved oxygen concentrations in the
bottom water. There is ample evidence that foraminifera can live in anoxic
sediments. For some species, this is explained by a switch to facultative
anaerobic metabolism (i.e. denitrification). Here we show for the first time
that adult specimens of three benthic foraminiferal species are not only able
to survive, but are also able to calcify under anoxic conditions, at various
depths in the sediment, and with or without nitrates. In fact, several
specimens of Ammonia tepida (1–4%), Bulimina
marginata (8–24%) and Cassidulina laevigata (16–23%)
were able to calcify at different redox fronts of sediment cores, under
laboratory conditions. This demonstrates ongoing metabolic processes, even in
micro-environments where denitrification is not possible. Earlier
observations suggest that the disappearance of foraminiferal communities
after prolonged anoxia is not due to instantaneous or strongly increased
adult mortality. Here we show that it cannot be explained by an inhibition of
growth through chamber addition either. Our observations of ongoing
calcification under anoxic conditions mean that geochemical proxy data
obtained from benthic foraminifera in settings experiencing intermittent
anoxia have to be reconsidered. The analysis of whole single specimens or of
their successive chambers may provide essential information about short-term
environmental variability and/or the causes of anoxia. |
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