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Titel |
The contribution of zooplankton faecal pellets to deep-carbon transport in the Scotia Sea (Southern Ocean) |
VerfasserIn |
C. Manno, G. Stowasser, P. Enderlein, S. Fielding, G. A. Tarling |
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 ; 12, no. 6 ; Nr. 12, no. 6 (2015-03-25), S.1955-1965 |
Datensatznummer |
250117880
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Publikation (Nr.) |
copernicus.org/bg-12-1955-2015.pdf |
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Zusammenfassung |
The northern Scotia Sea contains the largest seasonal uptake of atmospheric
carbon dioxide yet measured in the Southern Ocean. This study examines one
of the main routes by which this carbon fluxes to the deep ocean: through
the production of faecal pellets (FPs) by the zooplankton community. Deep
sediment traps were deployed at two sites with contrasting ocean
productivity regimes (P3, naturally iron-fertilized, and P2, iron-limited)
within the same water mass. The magnitude and seasonal pattern of
particulate organic carbon (POC) and FPs in the traps was markedly different
between the two sites. Maximum fluxes at P3 (22.91 mg C m−2 d−1;
2534 FP m−2 d1) were 1 order of magnitude higher than at P2
(4.01 mg C m−2 d−1; 915 FP m−2 d1, with flux at P3
exhibiting a double seasonal peak, compared to a single flatter peak at P2.
The maximum contribution of FP carbon to the total amount of POC was twice
as high at P3 (91%) compared to P2 (40%). The dominant FP category at
P3 varied between round, ovoidal, cylindrical and tabular over the course of
the year, while, at P2, ovoidal FPs were consistently dominant, always making
up more than 60% of the FP assemblage. There was also a difference in the
FP state between the two sites, with FPs being relatively intact at P3,
while FPs were often fragmented with broken peritrophic membranes at P2. The
exception was ovoidal FPs, which were relatively intact at both sites. Our
observations suggest that there was a community shift from a herbivorous to
an omnivorous diet from spring through to autumn at P3, while detritivores
had a higher relative importance over the year at P2. Furthermore, the flux
was mainly a product of the vertically migrating zooplankton community at P3,
while the FP flux was more likely to be generated by deeper-dwelling
zooplankton feeding on recycled material at P2. The results demonstrate that
the feeding behaviour and vertical distribution of the zooplankton community
plays a critical role in controlling the magnitude of carbon export to the
deep ocean in this region. |
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