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Marine Ecology Progress Series

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MEPS 465:281-297 (2012)  -  DOI:

Frontal zones, temperature gradient and depth characterize the foraging habitat of king penguins at South Georgia

Annette Scheffer1,2,*, Charles-André Bost2, Philip N. Trathan1

1British Antarctic Survey, National Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK
2Centre d’Etudes Biologiques de Chizé, CEBC-CNRS UPR 1934, 79360 Villiers-en-Bois, France

ABSTRACT: Investigating the responses of marine predators to oceanographic structures is of key importance for understanding their foraging behaviour and reproductive success. Using Global Positioning System (GPS) and Time-Depth-Temperature-Recorder (TDR) tags, we investigated how king penguins breeding at South Georgia explore their foraging area over the summer season in both the horizontal and vertical dimensions. We determined how horizontal habitat use may relate to different Antarctic Circumpolar Current (ACC) frontal zones and associated thermal structuring of the water column. To study the penguins’ use of the water column, we examined foraging niches defined by temperature, temperature gradient and depth, and explored the importance of these thermal properties for prey pursuit. King penguins foraged within the Polar Front (PF) and its southern edges during incubation, and the Antarctic Zone (AAZ) and Southern ACC Front (SACCF) during brooding. Foraging niches became more distinct with the advancing summer season, defined by strong thermal gradients at shallow depths in the AAZ, and weak gradients at greater depths in the SACCF. These niches indicate foraging in the sub-thermocline Winter Water (WW) in the AAZ, and in deep WW and Circumpolar Deep Water (CDW) at the SACCF. The influence of different ACC frontal zones in the area to the north of South Georgia appears to provide for a horizontally and vertically segregated environment. The presence of optional foraging areas and niches close to the colony clearly play an important role in these king penguins’ foraging success.

KEY WORDS: Aptenodytes patagonicus · Hydrological structure · Antarctic Circumpolar Current · Temperature gradient · Foraging niche · Seabird

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Cite this article as: Scheffer A, Bost CA, Trathan PN (2012) Frontal zones, temperature gradient and depth characterize the foraging habitat of king penguins at South Georgia. Mar Ecol Prog Ser 465:281-297.

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