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| Titel |
Seasonal variability of phytoplankton fluorescence in relation to the Straits of Messina (Sicily) tidal upwelling |
| VerfasserIn |
F. Azzaro, F. Decembrini, F. Raffa, E. Crisafi |
| 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 ; 3, no. 4 ; Nr. 3, no. 4 (2007-10-11), S.451-460 |
| Datensatznummer |
250001195
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| Publikation (Nr.) |
 copernicus.org/os-3-451-2007.pdf |
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| Zusammenfassung |
In the Straits of Messina, large gradients of tidal displacements, as well
as the topographic constrictions, determine the upwelling of deeper waters
in the surface layer. This work describes the seasonal variability in the
surface distribution of phytoplankton biomass depending on the upwelling
phenomena. Temperature, salinity, nitrates and phytoplankton fluorescence
were measured in 1994 and 1995 by continuous underway surface real-time
measurements onboard dedicated research boats. Each survey was performed
following the dynamic phases of flooding and ebbing tides. Tidal currents
are essentially southward during high tide and northward during low tide.
During the low water slack tide, large spatial gradients of
physical-chemical and biological parameters were found, while at the high
water slack tide, a diffused phytoplankton fluorescence was observed only in
autumn due to a seasonal thermocline. Salinity, nitrate and chlorophyll-a
fluorescence data revealed a significant positive intercorrelation, whereas
they were inversely correlated with temperature. Generally, the upwelling
distribution was limited to narrow zones during winter, while in summer it
was found in the middle of the Straits and in the southern zones. During
spring in the southern zone of the Straits, the maximum chlorophyll-a
fluorescence was detected (May 1995, 0.32 μg-Chla l−1); in summer,
when back and forth tidal movements between the Tyrrhenian and the Ionian
seas intensify, decreased values were observed throughout the study area.
The data set obtained through continuous and repeatable samplings has
allowed the study of different time-space scales in the Straits of Messina,
a very strong and dynamic environment.
The Straits system could be compared to an "intermittent pump" which, during
the different seasons, initially enriches itself and subsequently provides
nutrients to the surrounding basins. |
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