Linking foraging behaviour to physical oceanographic structures: Southern elephant seals and mesoscale eddies east of Kerguelen Islands

• Published in: Progress in Oceanography
• Main Authors: Dragon, Anne-Cécile, Monestiez, Pascal, Bar-Hen, Avner, Guinet, Christophe
• Other Authors: Centre d'Études Biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS), TAAF (Terres Australes et Antarctiques Francaises) 109
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: SPATIAL STRUCTURE; FORAGING BEHAVIOUR; OCEANIC PREDATOR; ELEPHANT SEAL; DIVING BEHAVIOUR; MESOSCALE; REMOTE SENSING; MIROUNGA LEONINA; PREDATEUR MARIN; ECOLOGIE MARINE; TOURBILLON CYCLONIQUE; [SDE]Environmental Sciences; Antarctic; Kerguelen; Kerguelen Islands; Southern Ocean; Antarc*; Elephant Seal; Elephant Seals; Mirounga leonina; Southern Elephant Seals
• Online Access: https://hal.science/hal-00546929; https://doi.org/10.1016/j.pocean.2010.09.025

International audience In the Southern Ocean, mesoscale features, such as fronts and eddies, have been shown to have a significant impact in structuring and enhancing primary productivity. They are therefore likely to influence the spatial structure of prey fields and play a key role in the creation of preferred foraging regions for oceanic top-predators. Optimal foraging theory predicts that predators should adjust their movement behaviour in relation to prey density. While crossing areas with sufficient prey density, we expect predators would change their behaviour by, for instance, decreasing their speed and increasing their turning frequency. Diving predators would as well increase the useful part of their dive i.e. increase bottom-time thereby increasing the fraction of time spent capturing prey. Southern elephant seals from the Kerguelen population have several foraging areas: in Antarctic waters, on the Kerguelen Plateau and in the interfrontal zone between the Subtropical and Polar Fronts. This study investigated how the movement and diving behaviour of 22 seals equipped with satellite-relayed data loggers changed in relation to mesoscale structures typical of the interfrontal zone. We studied the links between oceanographic variables including temperature and sea level anomalies, and diving and movement behaviour such as displacement speed, diving duration and bottom-time. Correlation coefficients between each of the time series were calculated and their significance tested with a parametric bootstrap. We focused on oceanographic changes, both temporal and spatial, occurring during behavioural transitions in order to clarify the connections between the behaviour and the marine environment of the animals. We showed that a majority of seals displayed a specific foraging behaviour related to the presence of both cyclonic and anticyclonic eddies. We characterized mesoscale oceanographic zones as either favourable or unfavourable based on the intensity of foraging activity as identified by the behavioural ...