Three-dimensional space use during the bottom phase of southern elephant seal dives

• Main Authors: Bras, Yves, Jouma’A, Joffrey, Guinet, Christophe
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Figshare 2017
• Subjects: Cell Biology; 59999 Environmental Sciences not elsewhere classified; FOS Earth and related environmental sciences; Ecology; FOS Biological sciences; 69999 Biological Sciences not elsewhere classified; Inorganic Chemistry; FOS Chemical sciences; Elephant Seal; Elephant Seals; Southern Elephant Seal; Southern Elephant Seals
• Online Access: https://dx.doi.org/10.6084/m9.figshare.c.3869152; https://springernature.figshare.com/collections/Three-dimensional_space_use_during_the_bottom_phase_of_southern_elephant_seal_dives/3869152

Abstract Background In marine pelagic ecosystems, the spatial distribution of biomass is heterogeneous and dynamic. At large scales, physical processes are the main driving forces of biomass distribution. At fine scales, both biotic and abiotic parameters are likely to be key determinants in the horizontal and vertical distribution of biomass, with direct consequences on the foraging behaviour of diving predators. However, fine scale three-dimensional (3D) spatial interactions between diving predators and their prey are still poorly known. Results We reconstructed and examined the patterns of southern elephant seals 3D path during the bottom phase of their dives, and related them to estimated prey encounter density. We found that southern elephant seal tracks at bottom are strongly dominated by a single horizontal direction. In high prey density areas, seals travelled shorter distances but their track remained strongly orientated according to a main linear direction. Horizontal, and more importantly, vertical deviations from this main direction, were related negatively to the estimated prey density. We found that prey encounter density decreased with diving depth but tended to be more predictable. Conclusion Southern elephant seal behaviour during the bottom phase of their dives suggest that the prey are dispersed and distributed into layers in which their density relates to the vertical spread of the layer. The linear trajectories performed by the elephant seals would allow to explore the largest volume of water, maximizing the opportunities of prey encounter, while travelling great horizontal distances.