Coastal polynyas: winter oases for subadult southern elephant seals in East Antarctica

• Published in: Scientific Reports
• Main Authors: Labrousse, S, Williams, G, Tamura, T, Bestley, S, Sallee, J-B, Fraser, AD, Sumner, M, Roquet, F, Heerah, K, Picard, B, Guinet, C, Harcourt, R, McMahon, C, Hindell, MA, Charrassin, J-B
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2018
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Antarctic; The Antarctic; East Antarctica; Kerguelen; Antarc*; Antarctica; Elephant Seals; Sea ice; Southern Elephant Seals
• Online Access: https://doi.org/10.1038/s41598-018-21388-9; http://www.ncbi.nlm.nih.gov/pubmed/29453356; http://ecite.utas.edu.au/130086

Antarctic coastal polynyas are regions of persistent open water and are thought to be key bio-physical features within the sea-ice zone. However, their use by the upper trophic levels of ecosystems remains unclear. A unique bio-physical dataset recorded by southern elephant seals reveals that East Antarctic polynyas are a key winter foraging habitat for male seals. During their post-moult trips from Isles Kerguelen to the Antarctic continental shelf, a total of 18 out of 23 seals visited 9 different polynyas, spending on average 25 20% (up to 75%) of their total trip time inside polynyas. Changes in seal foraging and diving behaviours are observed inside polynyas as compared to outside polynyas. Two polynya usages by seals are observed for the inactive and active polynya phases, pointing to different seasonal peaks in prey abundance. During the active polynya phase, we link seal foraging behaviour to changes in the physical stability of the water-column, which likely impact the seasonal biological dynamics within polynyas.