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| Titel |
Live (Rose Bengal stained) foraminiferal faunas from the northern Arabian Sea: faunal succession within and below the OMZ |
| VerfasserIn |
C. Caulle, K. A. Koho, M. Mojtahid, G. J. Reichart, F. J. Jorissen |
| 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. 4 ; Nr. 11, no. 4 (2014-02-26), S.1155-1175 |
| Datensatznummer |
250117248
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| Publikation (Nr.) |
 copernicus.org/bg-11-1155-2014.pdf |
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| Zusammenfassung |
| Live (Rose Bengal stained) benthic foraminifera from
the Murray Ridge, within and below the northern Arabian Sea oxygen minimum
zone (OMZ), were studied in order to determine the relationship between
faunal composition, bottom water oxygenation (BWO), pore water chemistry and
organic matter (organic carbon and phytopigment) distribution. A series of
multicores were recovered from a ten-station oxygen (BWO: 2–78 μM)
and bathymetric (885–3010 m depth) transect during the winter monsoon in
January 2009. Foraminifera were investigated from three different size
fractions (63–125 μm, 125–150 μm and
>150 μm). The larger foraminifera (>125 μm)
were strongly dominated by agglutinated species (e.g. Reophax
spp.). In contrast, in the 63–125 μm fraction, calcareous taxa
were more abundant, especially in the core of the OMZ. On the basis of a
principal components analysis, three foraminiferal groups were identified and
correlated to the environmental parameters by canonical correspondence
analysis. The faunas from the shallowest stations, in the core of the OMZ
(BWO: 2 μM), were composed of "low oxygen" species, typical of
the Arabian Sea OMZ (e.g. Rotaliatinopsis semiinvoluta,
Praeglobobulimina sp., Bulimina exilis, Uvigerina
peregrina type parva). These taxa are adapted to the very low BWO
conditions and to high phytodetritus supplies. The transitional group,
typical for the lower part of the OMZ (BWO: 5–16 μM), is composed
of species that are tolerant as well to low-oxygen concentrations, but may
be less critical with respect to organic supplies (e.g.
Globocassidulina subglobosa, Ehrenbergina trigona). Below
the OMZ (BWO: 26–78 μM), where food availability is more limited
and becomes increasingly restricted to surficial sediments, cosmopolitan
calcareous taxa were present, such as Bulimina aculeata,
Melonis barleeanus, Uvigerina peregrina and
Epistominella exigua. Miliolids were uniquely observed in this last
zone, reflecting the higher BWO and/or lower organic input. At these deeper
sites, the faunas exhibit a clear succession of superficial, intermediate and
deep infaunal microhabitats, which can be linked to the deeper oxygen and
nitrate penetration into the sediment. |
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