Sex-specific variation in the use of vertical habitat by a resident Antarctic top predator

• Published in: Proceedings of the Royal Society B: Biological Sciences
• Main Authors: Photopoulou, Theoni, Heerah, Karine, Pohle, Jennifer, Boehme, Lars
• Other Authors: NERC, University of St Andrews.Centre for Research into Ecological & Environmental Modelling, University of St Andrews.Scottish Oceans Institute, University of St Andrews.School of Biology, University of St Andrews.Sea Mammal Research Unit, University of St Andrews.Marine Alliance for Science & Technology Scotland
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Diving behaviour; Water mass; Continental shelf; Weddell seal; Sex-specific variation; Hidden Markov model; GC Oceanography; QH301 Biology; DAS; BDC; R2C; SDG 14 - Life Below Water; GC; QH301; Antarctic; Weddell Sea; Austral; Weddell; Antarc*; Antarctica; Weddell Seal
• Online Access: https://hdl.handle.net/10023/20811; https://doi.org/10.1098/rspb.2020.1447

Funding: The data collection was funded by NERC grant nos NE/G014833/1 and NE/G014086/1. T.P. was supported by a Royal Society Newton International Fellowship (NF170682). K.H. was supported by a Marie-Skłodowska Curie Research Fellowship. Patterns of habitat use are commonly studied in horizontal space, but this does not capture the four-dimensional nature of ocean habitats (space, depth, and time). Deep-diving marine animals encounter varying oceanographic conditions, particularly at the poles, where there is strong seasonal variation in vertical ocean structuring. This dimension of space use is hidden if we only consider horizontal movement. To identify different diving behaviours and usage patterns of vertically distributed habitat, we use hidden Markov models fitted to telemetry data from an air-breathing top predator, the Weddell seal, in the Weddell Sea, Antarctica. We present evidence of overlapping use of high-density, continental shelf water masses by both sexes, as well as important differences in their preferences for oceanographic conditions. Males spend more time in the unique high-salinity shelf water masses found at depth, while females also venture off the continental shelf and visit warmer, shallower water masses. Both sexes exhibit a diurnal pattern in diving behaviour (deep in the day, shallow at night) that persists from austral autumn into winter. The differences in habitat use in this resident, sexually monomorphic Antarctic top predator suggest a different set of needs and constraints operating at the intraspecific level, not driven by body size. Peer reviewed