title: Seasonal Variation of Harbor Seal's Diet from the Wadden Sea in Relation to Prey Availability.
abstract: The Wadden Sea has an important role for marine mammals in terms of resting, nursing and foraging. Harbor seal is the most abundant marine mammal species in this area. The use of the food resources of the Wadden Sea by seals is not clear, and previous studies showed that this species can travel kilometers away from their haul-outs to forage in the North Sea. In this study, we analyzed the stable isotopes of vibrissae from 23 dead harbor seals found on the island of Sylt to investigate their diet. The predator´s carbon and nitrogen isotope compositions were compared to the compositions of different potential prey items from the Sylt-Rømø Bight and from the North Sea in order to study seasonal pattern in the diet and in the foraging location. In parallel, seasonal variation of abundance and biomass of the potential prey items from the Sylt-Rømø Bight were studied and compare to their contribution to the seal´s diet. The results revealed a change in the seal´s diet from pelagic sources in spring to a benthic based diet in summer, and an increasing use of the North Sea resources in fall and winter in accordance with the seasonal variation of the availability of prey in the Sylt-Rømø Bight.
authors.affiliation: AlfredWegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Wattenmeerstation Sylt Hafenstr. 43, D-25992 List/ Sylt, Germany.
authors.forename: Camille
authors.initials: C
authors.lastname: de la Vega
authors.affiliation: Littoral Environnement et Sociétés (LIENSs), CNRS-Université de la Rochelle, Bâtiment ILE 2, rue Olympe de Gouges 17 000 La Rochelle, France.
authors.forename: Benoit
authors.initials: B
authors.lastname: Lebreton
authors.affiliation: Stiftung Tierärztliche Hochschule Hannover Institut für Terrestrische und Aquatische Wildtierforschung Werftstr. 6, 25761 Büsum, Germany.
authors.forename: Ursula
authors.initials: U
authors.lastname: Siebert
authors.affiliation: Littoral Environnement et Sociétés (LIENSs), CNRS-Université de la Rochelle, Bâtiment ILE 2, rue Olympe de Gouges 17 000 La Rochelle, France.
authors.forename: Gael
authors.initials: G
authors.lastname: Guillou
authors.affiliation: Laboratory of oceanology-MARE center, Université de Liège, Allée de la Chimie 3, Bât. B6c, 4000 Liège (Sart-Tilman), Belgium.
authors.forename: Krishna
authors.initials: K
authors.lastname: Das
authors.affiliation: AlfredWegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Wattenmeerstation Sylt Hafenstr. 43, D-25992 List/ Sylt, Germany.
authors.forename: Ragnhild
authors.initials: R
authors.lastname: Asmus
authors.affiliation: AlfredWegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Wattenmeerstation Sylt Hafenstr. 43, D-25992 List/ Sylt, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Asmus
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D018533:Biomass; D002247:Carbon Isotopes; D004032:Diet; D005260:Female; D020387:Food Chain; D005843:Geography; D008297:Male; D009587:Nitrogen Isotopes; D009659:North Sea; D046049:Phoca / Q000502:physiology*; D011235:Predatory Behavior / Q000502:physiology*; D012621:Seasons; D013045:Species Specificity; D014738:Vibrissae / Q000502:physiology
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes