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| Titel |
Observations of a phytoplankton spring bloom onset triggered by a density front in NW Mediterranean |
| VerfasserIn |
A. Olita, S. Sparnocchia, S. Cusí, L. Fazioli, R. Sorgente, J. Tintoré, A. Ribotti |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 10, no. 4 ; Nr. 10, no. 4 (2014-07-14), S.657-666 |
| Datensatznummer |
250117038
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| Publikation (Nr.) |
 copernicus.org/os-10-657-2014.pdf |
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| Zusammenfassung |
| Phytoplankton blooms in the northwestern Mediterranean Sea are seasonal
events that mainly occur in a specific area comprising the Gulf of Lion and
the Provençal basin, where they are promoted by a general cyclonic
circulation, strong wind-driven mixing and subsequent re-stratification of
the water column. At the southern boundary of this area, a persistent density
front known as the north Balearic front can be found. The front is presumed
to cause an early phytoplankton bloom in its vicinity because (a) it enhances
the transport of nutrients into the euphotic layer and (b) it promotes the
speedy re-stratification of the water column (through frontal instabilities).
In February and March 2013, a glider, equipped with a CTD (conductivity, temperature, and depth device) and a fluorometer, was
deployed on a mission that took it from the Balearic Islands to Sardinia and
back. The frontal zone was crossed twice, once during the outbound leg and
the once on the return leg. The data provided by the glider clearly showed
the onset of a bloom soon after a decrease in wind-driven turbulent
convection and mixing. The in situ observations were supported and confirmed
by satellite imagery. It is shown that frontal dynamics play a key role in
the promotion and acceleration of re-stratification, which is a necessary
pre-conditioning factor for the onset of blooms much like other relevant
processes such as an enhanced biological pump. Swift re-stratification
stimulates new production by inhibiting mixing. Finally, viewing the blooming
phenomenon from a regional perspective, it seems that Sverdrup's critical
depth model applies in the northern well-mixed area whereas, in the south,
front-related re-stratification seems to be the principal cause. |
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