Beneath the sea ice

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> JEUDI 1ER DÉCEMBRE 2016, 11h00 \ 11h45
Beneath the sea ice: exploring elephant seal foraging
strategy in Earth's extreme Antarctic polar environment
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.
par
Sara Labrousse
UMR Laboratoire d'Océanographie et du Climat (LOCEAN), Paris
Salle Mont St-Clair, Station Ifremer, avenue Jean Monnet, Sète
UMR MARBEC (IRD, Ifremer, Université de Montpellier, CNRS) ✆ 04 99 57 32 50 - 04 67 14 47 32 \ www.umr-marbec.fr
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Jeudi 8 décembre à Sète :
Paul Taconet (IRD, UMR MARBEC)