Verbreitung, Jahresdynamik und Bestandsentwicklung der Seetaucher Gavia spec. in der Deutschen Bucht (Nordsee)

Garthe, Stefan, Schwemmer, H., Markones, N., Müller, S. and Schwemmer, P. (2015) Verbreitung, Jahresdynamik und Bestandsentwicklung der Seetaucher Gavia spec. in der Deutschen Bucht (Nordsee) Vogelwarte, 53 . pp. 121-138.

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One of the most important wintering sites for Red-throated Divers Gavia stellata is the offshore zone of the German North Sea. The implementation of the EU Birds Directive in German offshore waters requires special protection of divers that comprise mainly Red-throated and Black-throated G. arctica Divers. An important first step concerning the protection was the establishment of two Special Protection areas for birds in the EEZ of the North and Baltic Seas in 2004. Anthropogenic activities at sea, such as the construction of offshore wind farms or ship traffic, have strong impacts on divers. In the course of the ongoing marine spatial planning it is particularly important to improve the knowledge on distribution patterns and phenology of divers in the German part of the North Sea. This publication presents the most recent analysis of spatio-temporal patterns of divers in the German North Sea. By merging data from scientific projects and environmental impact studies, the data basis could be considerably improved. Divers were recorded by ship-based and aerial surveys during 2000 to 2013. Distribution patterns on a 1 km x 1 km grid were interpolated using Generalized Additive Models. The first nameable aggregations of divers during the course of the year are found in the area of East Frisia during October. Abundance values increase constantly during the following weeks. Eventually, divers are found in the whole coastal zone of the German North Sea during the winter months. Areas of main abundance shift seawards during spring with high density areas occurring in and around the Special Protection Area “Eastern German Bight” off the island of Sylt. Several wind farm sites overlap with hot spots of diver distribution. The mean spring population of divers in the German North Sea was calculated at 20,000 individuals for the period 2002 to 2013. Numbers in spring did not significantly increase or decrease over this period. The most recent data on diver abundance reflect certain regional, annual variability that can most likely be explained by varying abundance in bentho-pelagic fish stocks as well as by variances in the hydrodynamic systems. The core aggregation of divers during spring could constantly be found within the region of the Special Protection Area “Eastern German Bight” over the course of the last years. However, most recent data still underline that the core area extends west outside the borders of the protected area. Some of the wind farms already established clearly overlap with the main distribution areas of divers.

Document Type: Article
Research affiliation: Kiel University > Kiel Marine Science
OceanRep > The Future Ocean - Cluster of Excellence
Kiel University
Refereed: Yes
Projects: Future Ocean
Date Deposited: 30 Jan 2017 10:09
Last Modified: 30 Jan 2017 10:09

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