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| Titel |
Uptake of algal carbon and the likely synthesis of an "essential" fatty acid by Uvigerina ex. gr. semiornata (Foraminifera) within the Pakistan margin oxygen minimum zone: evidence from fatty acid biomarker and 13C tracer experiments |
| VerfasserIn |
K. E. Larkin, A. J. Gooday, C. Woulds, R. M. Jeffreys, M. Schwartz, G. Cowie, C. Whitcraft, L. Levin, J. R. Dick, D. W. Pond |
| 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 (2014-07-18), S.3729-3738 |
| Datensatznummer |
250117514
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| Publikation (Nr.) |
 copernicus.org/bg-11-3729-2014.pdf |
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| Zusammenfassung |
| Foraminifera are an important component of benthic communities in
oxygen-depleted settings, where they potentially play a significant role in
the processing of organic matter. We tracked the uptake of a
13C-labelled algal food source into individual fatty acids in the
benthic foraminiferal species Uvigerina ex. gr. semiornata
from the Arabian Sea oxygen minimum zone (OMZ). The tracer experiments were
conducted on the Pakistan margin during the late/post monsoon period
(August–October 2003). A monoculture of the diatom Thalassiosira
weisflogii was 13C-labelled and
used to simulate a pulse of phytoplankton in two complementary experiments. A
lander system was used for in situ incubations at 140 m water depth and for
2.5 days in duration. Shipboard laboratory incubations of cores collected at
140 m incorporated an oxystat system to maintain ambient dissolved oxygen
concentrations and were terminated after 5 days. Uptake of diatoms was rapid,
with a high incorporation of diatom fatty acids into foraminifera after
~ 2 days in both experiments. Ingestion of the diatom food source was
indicated by the increase over time in the quantity of diatom biomarker fatty
acids in the foraminifera and by the high percentage of 13C in many of
the fatty acids present at the endpoint of both in situ and laboratory-based
experiments. These results indicate that . ex. gr. semiornata
rapidly ingested the diatom food source and that these foraminifera will play
an important role in the short-term cycling of organic matter within this OMZ
environment. The presence of 18:1(n-7) in the experimental foraminifera
suggested that U. ex. gr. semiornata also consumed non-labelled
bacterial food items. In addition, levels of 20:4(n-6), a PUFA only present
in low amounts in the diatom food, increased dramatically in the foraminifera
during both the in situ and shipboard experiments, possibly because it was
synthesised de novo. This "essential fatty acid" is often abundant in
benthic fauna, yet its origins and function have remained unclear. If
U. ex. gr. semiornata is capable of de novo synthesis of
20:4(n-6), then it represents a potentially major source of this dietary
nutrient in benthic food webs. |
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