1erdécembre 2016

Beneath the sea ice : exploring elephant seal foraging strategy in Earth’s extreme Antarctic polar environment

Par: Sara Labrousse UMR Laboratoire d’Océanographie et du Climat (LOCEAN), Paris Lieu: Salle Mont St-Clair UMR MARBEC, Station Ifremer Avenue Jean Monnet, Sète

Understanding how physical properties of the environment underpin habitat selection of large marine vertebrates is crucial in identifying how and where animals acquire resources necessary for locomotion, growth and reproduction and ultimately their fitness. The Southern Ocean harbors one of the largest and most dynamic marine ecosystems on our planet which arises from the presence of two major physical features dominating the ecosystem dynamics, (i) the Antarctic Circumpolar Current and (ii) the seasonal sea ice cover region. In the Antarctic, marine predators are exposed to climate-induced shifts in atmospheric circulation and sea ice. However, because these shifts vary regionally, and because much remains to be understood about how individual animals use their environment, it has been difficult to make predictions on how animals may respond to climate variability. Spatio-temporal variability in ecosystem structure and function are likely to translate into modification of top predator population dynamics, however, there is currently a long-standing gap in our understanding of ecosystem functioning under winter Antarctic sea ice. Southern elephant seals (Mirounga leonina) are circumpolar deep-diving predators (average diving depth of 500 m and up to 2000 m), major consumers of Southern Ocean resources and use two main large scale foraging strategies, (i) feeding in the frontal zone of the Southern Ocean, or (ii) feeding in the seasonal sea ice region. In the present thesis we examined the winter post-moulting foraging strategies of 46 male and female Kerguelen southern elephant seals which utilized the second strategy. Using an eleven year time-series of tracking, diving, and seal-collected hydrographic data (from 2004-2014) we assessed their movements and foraging performance in relation to in situ hydrographic and sea ice conditions. The influence of both the spatio-temporal and inter-annual variability of sea ice around seal locations was investigated, and an investigation on the role of polynya for male elephant seal during winter conducted.
Beneath the sea ice : exploring elephant seal foraging strategy in Earth’s extreme Antarctic polar environment

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MARBEC MARine Biodiversity, Exploitation and Conservation, est une unité de recherche qui regroupe des personnels de 4 organismes : l’IRD, l’Ifremer, l’UM et le CNRS. Son objectif est l’étude de la biodiversité marine des écosystèmes lagunaires, côtiers et hauturiers à différents niveaux d’intégration, depuis les aspects moléculaires, individuels, populationnels et communautaires, et des usages de cette biodiversité par l’Homme. Nous rejoindre