[MARMAM] Under the sea ice: Exploring the relationship between sea ice and the foraging behaviour of southern elephant seals in East Antarctica

Sara Labrousse sara.labrousse at gmail.com
Mon Jun 12 00:38:41 PDT 2017


Dear all,

My co-authors and I are pleased to bring to your attention the following
publication :

Sara Labrousse, Jean-Baptiste Sallée, Alexander D. Fraser, Robert A.
Massom, Phillip Reid, Michael Sumner, Christophe Guinet, Robert Harcourt,
Clive McMahon, Frédéric Bailleul, Mark A. Hindell, Jean-Benoit
Charrassin, *Under
the sea ice: Exploring the relationship between sea ice and the foraging
behaviour of southern elephant seals in East Antarctica*, Progress in
Oceanography, Volume 156, August 2017, Pages 17-40, ISSN 0079-6611,
https://doi.org/10.1016/j.pocean.2017.05.014.

Abstract:
Investigating ecological relationships between predators and their
environment is essential to understand the response of marine ecosystems to
climate variability and change. This is particularly true in polar regions,
where sea ice (a sensitive climate variable) plays a crucial yet highly
dynamic and variable role in how it influences the whole marine ecosystem,
from phytoplankton to top predators. For mesopredators such as seals, sea
ice both supports a rich (under-ice) food resource, access to which depends
on local to regional coverage and conditions. Here, we investigate
sex-specific relationships between the foraging strategies of southern
elephant seals (*Mirounga leonina*) in winter and spatio-temporal
variability in sea ice concentration (SIC) and coverage in East Antarctica.
We satellite-tracked 46 individuals undertaking post-moult trips in winter
from Kerguelen Islands to the peri-Antarctic shelf between 2004 and 2014.
These data indicate distinct general patterns of sea ice usage: while
females tended to follow the sea ice edge as it extended northward, the
males remained on the continental shelf despite increasing sea ice. Seal
hunting time, a proxy of foraging activity inferred from the diving
behaviour, was longer for females in late autumn in the outer part of the
pack ice, ~150 - 370 km south of the ice edge. Within persistent regions of
compact sea ice, females had a longer foraging activity (i) in the highest
sea ice concentration at their position, but (ii) their foraging activity
was longer when there were more patches of low concentration sea ice around
their position (either in time or in space; 30 days & 50km). The high
spatio-temporal variability of sea ice around female positions is probably
a key factor allowing them to exploit these concentrated patches. Despite
lack of information on prey availability, females may exploit mesopelagic
finfishes and squids that concentrate near the ice-water interface or
within the water column (from diurnal vertical migration) in the pack ice
region, likely attracted by an ice algal autumn bloom that sustains an
under-ice ecosystem. In contrast, male foraging effort increased when they
remained deep within the sea ice (420 - 960 km from the ice edge) over the
shelf. Males had a longer foraging activity (i) in the lowest sea ice
concentration at their position, and (ii) when there were more patches of
low concentration sea ice around their position (either in time or in
space; 30 days & 50km) presumably in polynyas or flaw leads between land
fast and pack ice. This provides access to zones of enhanced resources in
autumn or in early spring such as polynyas, the Antarctic shelf and slope.
Our results suggest that some seals utilized a highly sea ice covered
environment, which is key for their foraging effort, sustaining or
concentrating resources during winter.

The article can be download from:
http://www.sciencedirect.com/science/article/pii/S0079661116300441 or you
can email me for a copy.

Best regards,
Sara Labrousse

-- 
Sara Labrousse, Dr.
UPMC - LOCEAN
4 place Jussieu
Boite 100 - 45-55 4ème étage
75252 Paris cedex 05
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