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| Titel |
Silicate:nitrate ratios of upwelled waters control the phytoplankton community sustained by mesoscale eddies in sub-tropical North Atlantic and Pacific |
| VerfasserIn |
T. S. Bibby, C. M. Moore |
| 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 ; 8, no. 3 ; Nr. 8, no. 3 (2011-03-14), S.657-666 |
| Datensatznummer |
250005569
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| Publikation (Nr.) |
 copernicus.org/bg-8-657-2011.pdf |
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| Zusammenfassung |
| Mesoscale eddies in sub-tropical gyres physically perturb
the water column and can introduce macronutrients to the euphotic zone,
stimulating a biological response in which phytoplankton communities can
become dominated by large phytoplankton. Mesoscale eddies may therefore be
important in driving export in oligotrophic regions of the modern ocean.
However, the character and magnitude of the biological response sustained by
eddies is variable. Here we present data from mesoscale eddies in the
Sargasso Sea (Atlantic) and the waters off Hawai'i (Pacific), alongside
mesoscale events that affected the Bermuda Atlantic Time-Series Study (BATS)
over the past decade. From this analysis, we suggest that the phytoplankton
community structure sustained by mesoscale eddies is predetermined by the
relative abundance of silicate over nitrate (Si*) in the upwelled waters. We
present data that demonstrate that mode-water eddies (MWE) in the Sargasso
Sea upwell locally formed waters with relatively high Si* to the euphotic
zone, and that cyclonic eddies in the Sargasso Sea introduce waters with
relatively low Si*, a signature that originated in the iron-limited Southern
Ocean. We propose that this phenomenon can explain the observed dominance of
the phytoplankton community by large-diatom species in MWE and by small
prokaryotic phytoplankton in cyclonic features. In contrast to the Atlantic,
North Pacific Intermediate Water (NPIW) with high Si* may influence the
cyclonic eddies in waters off Hawai'i, which also appear capable of
sustaining diatom populations. These observations suggest that the structure
of phytoplankton communities sustained by eddies may be related to the
chemical composition of the upwelled waters in addition to the physical
nature of the eddy. |
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