La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Relationship between Great Crested Grebe numbers and water quality in lake Arreso.
Auteurs :	Ivan Abramowitz, Auteur ; Bo Johansen, Auteur
Type de document :	Article
Dans :	Dansk Ornitologisk Forenings Tidsskrift (95(4) 2001)
Article en page(s) :	149-152
Langues:	Anglais
Résumé :	The population of Great Crested Grebe Podiceps cristatus in Arreso, a hypereutrophic lake in northern Zealand, Denmark, is rather low, considering the size of the lake (41 km2). Grebe numbers have changed over time without any clear relationship to the - generally decreasing - phosphorus content of the water, and it is suggested instead that food competition with the predatory fish zander Lucioperca lucioperca is the main reason for the low grebe population in Arreso. Zander, which prefers turbid water, was introduced to lake Arreso in 1932, since when the stock appears to have fluctuated; in recent years it has been strong. Competition between Great Crested Grebe and other species of predatory fish is suggested in other lakes where grebe numbers declined after restoration measures had lead to improved conditions for the predatory fish.

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