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Dissertation zugänglich unter
URN: urn:nbn:de:gbv:18-46540
URL: http://ediss.sub.uni-hamburg.de/volltexte/2010/4654/

Investigatin environmental changes in the southern North Sea: a combined statistical assessment of climatic and biogeochemical long-term time series

Schlüter, Merja Helena

 Dokument 1.pdf (1.070 KB) 

SWD-Schlagwörter: Geesthacht / GKSS-Forschungszentrum
Freie Schlagwörter (Deutsch): Klimavariabilität , Ökosystem , hydrophysikalische Parameter , Helgoland Reede
Freie Schlagwörter (Englisch): Climate variability , regime shift , ecosystem , hydrophysical parameters , Helgoland Roads
Basisklassifikation: 38.80
Institut: Geowissenschaften
DDC-Sachgruppe: Geowissenschaften
Dokumentart: Dissertation
Hauptberichter: Storch, Hans von (Prof. Dr.)
Sprache: Englisch
Tag der mündlichen Prüfung: 08.06.2010
Erstellungsjahr: 2010
Publikationsdatum: 28.06.2010
Kurzfassung auf Englisch: The work presented in this thesis untangles the effects of changes in various physical and
biogeochemical variables on the ecosystem of the southern North Sea with an emphasis on
long–term variability. It is still a matter of debate how climate variations may affect the
functioning of the ecosystem. Therefore, this study provided for the first time a detailed understanding
of climate variability of the southeastern region of the North Sea, the German Bight,
during the period 1975–2004, by combining a wide set of physical, biological and chemical data.
The first part of this work used Principal Component Analysis to examine the bulk
variability of a diverse array of physical and biogeochemical long–term time series in
order to understand the main mode of variability of the climate and the ecosystem of the
coastal region. The outcomes motivated further investigations on the dynamic of the first
trophic levels of the ecosystem. Therefore, in the second part of this work, the factors that
drove the long–term seasonal variability of three most representative species of the diatom
community (Guinardia delicatula, Thalassionema nitzschioides and Odontella aurita) were
determined with multivariate linear regression analysis. Finally, in the third part, the results
on the seasonal variability of the three phytoplankton species were put into the wider
context of the German Bight ecosystem by studying the phenology of some important primary
and secondary consumers. Hence, the long–term abundance dynamics of Beroe gracilis,
Pleurobrachia pileus and their food calanoid copepods were analysed using Bayesian statistics.
Taken together, the results of this work revealed a more coherent picture of how and on
what time scales biology responds to physical changes and the inherent consequences for
the ecosystem. It was documented for the first time that the climate and the ecology of the
German Bight experienced patterns of variability similar to the ones of the entire North Sea.
The German Bight, however, is exposed to different natural and anthropogenic perturbations
when compared to the whole of the North Sea, detailed investigations on some key organisms have thus revealed the differential impacts of major driving factors on different species.
Although temperature variation was the major driver of changes in the abundance and seasonality
of primary and secondary consumers (top down effect), evidence was provided suggesting
the importance of bottom up processes. This work highlights the complex responses of a coastal
ecosystem to climate change and the high nonlinearities in the atmosphere–ocean–biosphere


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