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| Titel |
Reduced prokaryotic heterotrophic production at in situ pressure conditions in the dark ocean |
| VerfasserIn |
Chie Amano-Sato, Eva Sintes, Thomas Reinthaler, Motoo Utsumi, Gerhard J. Herndl |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250139243
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| Publikation (Nr.) |
 EGU/EGU2017-2440.pdf |
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| Zusammenfassung |
| Prokaryotic heterotrophic production (PHP) is a key process in the ocean’s biological carbon
cycle. About 50% of the oceanic PHP takes place in the dark ocean characterized by low
temperature and high hydrostatic pressure, which increases by 1 MPa (10 atm) every 100 m
depth. However, rate measurements of PHP are usually performed under atmospheric
pressure conditions. Yet, the difference in pressure conditions and the handling of the samples
on board may introduce biases in the PHP measurements.
To determine PHP at in situ conditions, we developed an in situ microbial incubator
(ISMI) designed to autonomously sample and incubate seawater down to a depth of 4000 m.
Natural prokaryotic communities from the North Atlantic and Pacific Oceans were incubated
in the ISMI with 5 nM 3H-leucine at different depths ranging between 10 and 3200 m. For
comparison, atmospheric pressure incubations at in situ temperature were also conducted.
PHP and single cell activity assessed by microautoradiography combined with catalyzed
reporter deposition fluorescence in situ hybridization (MICRO-CARD-FISH) were
determined.
PHP obtained under in situ pressure conditions was generally lower than under
atmospheric pressure conditions, suggesting that incubation under atmospheric pressure on
board stimulates activity of dark ocean prokaryotes. The ratio between the bulk PHP obtained
under in situ and under atmospheric pressure conditions decreased with depth. Moreover,
MICRO-CARD-FISH revealed that some specific prokaryotic groups are apparently more
affected by the hydrostatic pressure condition than others. Our results suggest that PHP in the
dark ocean might be lower than assumed based on measurements under surface pressure
conditions. |
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