Under the Sea Ice: Exploration of the Relationships Between Sea Ice Patterns and Foraging Movements of a Marine Predator in East Antarctica.

Sara Labrousse, Sorbonne Universités, UPMC Univ., Paris 06, UMR 7159 CNRS-IRD-MNHN, LOCEAN-IPSL, 75005 Paris, France; Woods Hole Oceanographic Institution, Biology, Woods Hole, MA, United States, Jean-baptiste Sallee, British Antarctic Survey, High Cross, Cambridge, CB3 0ET, UK, France; Sorbonne Universités, UPMC Univ., Paris 06, UMR 7159 CNRS-IRD-MNHN, LOCEAN-IPSL, 75005 Paris, France, France, Alexander D. Fraser, Hokkaido University, Institute of Low Temperature Science, Hokkaido, Japan; University of Tasmania, Institute of Marine and Antarctic Studies, Hobart, Australia, Rob A. Massom, Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia, Hobart, Australia; Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia, Hobart, Australia, Phillip Reid, Australian Bureau of Meteorology, Centre for Australian Weather and Climate Research, Hobart, Tasmania 7001, Australia, Michael Sumner, Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia, Christophe Guinet, Centre d’Etudes Biologiques de Chizé (CEBC), UMR 7372 Université de la Rochelle-CNRS, Villiers en Bois, France, Robert Harcourt, Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia, Australia, Frédéric Bailleul, South Australian Research and Development Institute, Adelaide, Australia, Mark Hindell, Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia; Marine Predator Unit, Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tasmania 7001, Australia and Jean-Benoit Charrassin, Sorbonne Universités, UPMC Univ., Paris 06, UMR 7159 CNRS-IRD-MNHN, LOCEAN-IPSL, Paris, France
Abstract:
Investigating ecological relationships between top predators and their environment is essential to understand the response of marine ecosystems to climate variability. Specifically, variability and changes in sea ice, which is known as an important habitat for marine ecosystems, presents complex patterns in East Antarctic. The impact for ecosystems of such changes of their habitat is however still unknown. Acting as an ecological double-edged sword, sea ice can impede access to marine resources while harboring a rich ecosystem during winter. Here, we investigated which type of sea ice habitat is used by male and female southern elephant seals during winter and examine if and how the spatio-temporal variability of sea ice concentration (SIC) influence their foraging strategies. We also examined over a 10 years time-series the impact of SIC and sea ice advance anomaly on foraging activity. To do this, we studied 46 individuals equipped with Satellite linked data recorders between 2004 and 2014, undertaking post-moult trips in winter from Kerguelen to the peri-Antarctic shelf. The general patterns of sea ice use by males and females are clearly distinct; while females tended to follow the sea ice edge as it extended northward, males remained on the continental shelf. Female foraging activity was higher in late autumn in the outer part of the pack ice in concentrated SIC and spatially stable. They remained in areas of variable SIC over time and low persistence. The seal hunting time, a proxy of foraging activity inferred from the diving behaviour, was much higher during earlier advance of sea ice over female time-series. The females were possibly taking advantage of the ice algal autumn bloom sustaining krill and an under ice ecosystem without being trapped in sea ice. Males foraging activity increased when they remained deep inside sea ice over the shelf using variable SIC in time and space, presumably in polynyas or flaw leads between fast and pack ice. This strategy probably gave them access to zones of enhanced resources in early spring such as polynyas, the Antarctic Slope Front, or the Antarctic shelf while avoiding the constraint of sea ice. Over years, males foraging activity were not affected by anomalies of sea ice advance, however negative SIC anomalies were profitable allowing them to use remote areas within sea ice.
Back to: Advances in the Ecology, Behavior, Physiology, or Conservation of Marine Top Predators II