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| Titel |
Distribution and recurrence of phytoplankton blooms around South Georgia, Southern Ocean |
| VerfasserIn |
I. Borrione, R. Schlitzer |
| 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 ; 10, no. 1 ; Nr. 10, no. 1 (2013-01-14), S.217-231 |
| Datensatznummer |
250017468
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| Publikation (Nr.) |
 copernicus.org/bg-10-217-2013.pdf |
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| Zusammenfassung |
| South Georgia phytoplankton blooms are amongst the largest of the Southern
Ocean and are associated with a rich ecosystem and strong atmospheric carbon
drawdown. Both aspects depend on the intensity of blooms, but also on their
regularity. Here we use data from 12 yr of SeaWiFS (Sea-viewing Wide
Field-of-view Sensor) ocean colour imagery and calculate the frequency of
bloom occurrence (FBO) to re-examine spatial and temporal bloom
distributions. We find that upstream of the island and outside the borders of
the Georgia Basin, blooms occurred in less than 4 out of the 12 yr
(FBO < 4). In contrast, FBO was mostly greater than 8 downstream of the
island, i.e., to the north and northwest, and in places equal to 12,
indicating that blooms occurred every year. The typical bloom area, defined
as the region where blooms occurred in at least 8 out of the 12 yr, covers
the entire Georgia Basin and the northern shelf of the island. The time
series of surface chlorophyll a (Chl a) concentrations averaged over the
typical bloom area shows that phytoplankton blooms occurred in every year
between September 1997 and September 2010, and that Chl a values followed a
clear seasonal cycle, with concentration peaks around December followed in
many years by a second peak during late austral summer or early autumn,
suggesting a bi-modal bloom pattern. The bloom regularity we describe here is
in contrast with results of Park et al. (2010) who used a significantly
different study area including regions that almost never exhibit bloom
conditions. |
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