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| Titel |
Qualitative and quantitative reconstructions of surface water characteristics and recent hydrographical changes in the Trondheimsfjord, central Norway |
| VerfasserIn |
G. Milzer, J. Giraudeau, S. Schmidt, F. Eynaud, J. Faust |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 1 ; Nr. 10, no. 1 (2014-02-12), S.305-323 |
| Datensatznummer |
250116912
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| Publikation (Nr.) |
 copernicus.org/cp-10-305-2014.pdf |
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| Zusammenfassung |
In the present study we investigated dinocyst assemblages in the
Trondheimsfjord over the last 25 to 50 yr from three well-dated multi-cores
(210Pb and 137Cs) retrieved along the fjord axis. The downcore
distribution of the dinocysts is discussed in view of changes in key
hydrographic parameters of the surface waters (sea-surface temperatures
(SSTs), sea-surface salinities (SSSs), and river discharges) monitored in the
fjord. We examine the impact of the North Atlantic Oscillation pattern and of
waste water supply from the local industry and agriculture on the fjord
ecological state and thus dinocyst species diversity. Our results show that
dinocyst production and diversity in the fjord is not evidently affected by
human-induced eutrophication. Instead the assemblages appear to be mainly
controlled by the NAO-related changes in nutrient availability and the
physico-chemical characteristics of the surface mixed layer. Still,
discharges of major rivers have been modulated since 1985 by the
implementation of hydropower plants, which certainly influences the amounts
of nutrients supplied to the fjord. The impact, however, is variable
according to the local geographical setting, and barely differentiated from
natural changes in river run off.
We ultimately test the use of the modern analogue technique (MAT) for the
reconstruction of winter and summer SSTs and SSSs and annual primary
productivity (PP) in this particular fjord setting. The reconstructed data
are compared with time series of summer and winter SSTs and SSSs measured at
10 m water depth, as well as with mean annual PPs along the Norwegian coast
and in Scandinavian fjords. The reconstructions are generally in good
agreement with the instrumental measurements and observations from other
fjords. Major deviations can be attributed to peculiarities in the
assemblages linked to the particular fjord setting and the related
hydrological structure. |
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