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| Titel |
Picoplankton community structure before, during and after convection event in the offshore waters of the Southern Adriatic Sea |
| VerfasserIn |
M. Najdek, P. Paliaga, T. Šilović, M. Batistić, R. Garić, N. Supić, I. Ivančić, S. Ljubimir, M. Korlević, N. Jasprica, E. Hrustić, I. Dupčić-Radić, M. Blažina, S. Orlić |
| 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 ; 11, no. 10 ; Nr. 11, no. 10 (2014-05-20), S.2645-2659 |
| Datensatznummer |
250117415
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| Publikation (Nr.) |
 copernicus.org/bg-11-2645-2014.pdf |
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| Zusammenfassung |
| This paper documents the picoplankton community's response to changes in
oceanographic conditions in the period between October 2011 and September
2012 at two stations belonging to the South Adriatic Pit (SAP). The recorded data
include the community's abundance, composition, prokaryotic production rates
and bacterial metabolic capacity. The sampling period included an intense sea
cooling with formation of exceptional, record-breaking dense water. We
documented an especially intense winter convection episode that completely
diluted the core of Levantine intermediate waters (LIW) in a large area
encompassing the SAP's center and its margin. During this convection event
the whole picoplankton community had significantly higher abundances with a
recorded picoeukaryotic peak at the SAP margin. In the post-convection phase
in March, prokaryotic heterotrophic production strongly increased in the
entire SAP area (up to 50 times; 456.8 nM C day−1). An autotrophic
biomass increase (up to 5 times; 4.86 μg L−1) and a
disruption of a close correspondence between prokaryotic heterotrophic
biomass production and cell replication rates were observed only in the
center of the SAP, which was not under the influence of LIW. At the SAP's
margin such an effect was attenuated by LIW, since the waters affected by LIW
were characterized by decreased concentrations of dissolved inorganic
nitrogen, decreased autotrophic biomasses, and by increased bacterial biomass
production balanced with cell replication rates as well as by the domination
of Synechococcus among autotrophic picoplankton. The metabolic
capacity was lowest in spring when autotrophic biomass largely increased,
while the highest levels found in the pre-convection phase (October 2011)
suggest that the system was more oligotrophic before than after the
convection event. Furthermore, we showed that metabolic capacity is a trait
of bacterial community independent of environmental conditions and tightly
linked to cell replication and substrate availability. In contrast, the
bacterial community composition appears to be strongly influenced by
physico-chemical characteristics of waters (e.g., temperature and nutrients)
and environmental forcing (e.g., convection and LIW). Our results showed that
the two oceanographic phenomena of the Southern Adriatic, strongly relevant
for the total production of the Adriatic Sea, winter convection and LIW
intrusion, regulate the changes in picoplankton community structure and
activities. |
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