Mesoscale activity facilitates energy gain in a top predator

• Published in: Proceedings of the Royal Society B: Biological Sciences
• Main Authors: Abrahms, Briana, Scales, Kylie L, Hazen, Elliott L, Bograd, Steven J, Schick, Robert S, Robinson, Patrick W, Costa, Daniel P
• Format: Article in Journal/Newspaper
• Language: English
• Published: Royal Society Publishing 2018
• Subjects: FoR 06 (Biological Sciences); FoR 07 (Agricultural and Veterinary Sciences); FoR 11 (Medical and Health Sciences); body condition; elephant seal; energy transfer; foraging; Lagrangian coherent structures; resource selection; Elephant Seal; Elephant Seals
• Online Access: https://doi.org/10.1098/rspb.2018.1101

How animal movement decisions interact with the distribution of resources to shape individual performance is a key question in ecology. However, links between spatial and behavioural ecology and fitness consequences are poorly understood because the outcomes of individual resource selection decisions, such as energy intake, are rarely measured. In the open ocean, mesoscale features (approx. 10–100 km) such as fronts and eddies can aggregate prey and thereby drive the distribution of foraging vertebrates through bottom-up biophysical coupling. These productive features are known to attract predators, yet their role in facilitating energy transfer to top-level consumers is opaque. We investigated the use of mesoscale features by migrating northern elephant seals and quantified the corresponding energetic gains from the seals' foraging patterns at a daily resolution. Migrating elephant seals modified their diving behaviour and selected for mesoscale features when foraging. Daily energy gain increased significantly with increasing mesoscale activity, indicating that the physical environment can influence predator fitness at fine temporal scales. Results show that areas of high mesoscale activity not only attract top predators as foraging hotspots, but also lead to increased energy transfer across trophic levels. Our study provides evidence that the physical environment is an important factor in controlling energy flow to top predators by setting the stage for variation in resource availability. Such understanding is critical for assessing how changes in the environment and resource distribution will affect individual fitness and food web dynamics.