Seasonal variation of harbor seal's diet from the Wadden Sea in relation to prey availability

• Published in: PLOS ONE
• Main Authors: de La Vega, Camille, Lebreton, Benoit, Siebert, Ursula, Guillou, Gael, Das, Krishna, Asmus, Ragnhild, Asmus, Harald
• Other Authors: Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), LIttoral ENvironnement et Sociétés - UMR 7266 (LIENSs), Institut national des sciences de l'Univers (INSU - CNRS)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover Foundation (TiHo), Laboratory of oceanology — MARE center, Université de Liège
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: Seasonal variation; Harbor seal; Stable isotopes; Wadden Sea; Diet; [SDV.BA.ZV]Life Sciences [q-bio]/Animal biology/Vertebrate Zoology; [SDE]Environmental Sciences; harbor seal
• Online Access: https://hal.science/hal-01340654; https://hal.science/hal-01340654/document; https://hal.science/hal-01340654/file/journal.pone.0155727.PDF; https://doi.org/10.1371/journal.pone.0155727

International audience 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.