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Margrethe-Kog and the Artificial Saltwater Lagoon: Evaluation of a Habitat Restoration Project in the Danish Wadden Sea

Published online by Cambridge University Press:  24 August 2009

Knud Falk ,
Henning Nøhr  and
Lars Maltha Rasmussen
Lars Maltha Rasmussen
Affiliation:
Ornis Consult Ltd, Vesterbrogade 140, DK-1620 Copenhagen V, Denmark.
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Extract

Across the Danish–German border in the Wadden Sea, a new dike was completed in 1981, enclosing formerly productive tidal flats and marsh areas which were most important as feeding grounds to breeding and migrant waterbirds. The bird populations responded immediately by a 50% or more reduction in numbers of resting birds and breeding pairs of most species. This paper reviews the management of the enclosed areas, comparing the differences in approach in the Danish and German areas involved.

Most importantly, a saline environment was re-established (a Saltwater Lagoon) in parts of the Danish area by actively pumping in water from the Wadden Sea. Despite sometimes drastic fluctuations in environmental conditions in the Lagoon, an infauna of species important in the birds' diet was maintained, and the Lagoon to some extent counteracted the negative effects of the dike construction.

The former marsh areas on the Danish side are drained and partly cultivated. In addition, the land areas are separated from the Lagoon by a dike, preventing a saline environment from being maintained outside the designated Saltwater Lagoon. Overall, the land areas in the Danish part are too dry and intensively used to be optimal to the breeding birds.

After construction of the dike, the breeding bird populations shifted more towards the German areas. Here, the land-use is much more beneficial to the breeding birds, because no cultivation has taken place, and a generally high water-level in the marsh areas is preserved. Furthermore, in Germany the new dike was placed closer to the original coastline than in Denmark, but a small area of the original foreland remained outside the dike, providing good breeding sites for colonial waterbirds.

It is concluded that, due to the creation of the Saltwater Lagoon, the Danish part of the area again sustains waterbirds in numbers of international importance. But an integrated approach to the Nature management of the enclosed areas — combining the solutions adopted for land management in the German part with the technical solution of re-establishing a saline environment behind the dike as in the Danish part — would have rendered a better compensation for the damage caused by the dike construction and related activities.

Type
Main Papers
Information
Environmental Conservation , Volume 21 , Issue 2 , Summer 1994 , pp. 133 - 144
Copyright
Copyright © Foundation for Environmental Conservation 1994

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