Flash and grab : deep-diving southern elephant seals trigger anti-predator flashes in bioluminescent prey

• Published in: Journal of Experimental Biology
• Main Authors: Goulet, Pauline, Guinet, Christophe, Campagna, Claudio, Campagna, Julieta, Tyack, Peter Lloyd, Johnson, Mark
• Other Authors: European Commission, University of St Andrews.School of Biology, University of St Andrews.Centre for Social Learning & Cognitive Evolution, University of St Andrews.Marine Alliance for Science & Technology Scotland, University of St Andrews.Sound Tags Group, University of St Andrews.Bioacoustics group, University of St Andrews.Sea Mammal Research Unit, University of St Andrews.Scottish Oceans Institute
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: Anti-predator tactic; Bioluminescence; Biologging; Mirounga leonina; Foraging ecology; Predator-prey interactions; QH301 Biology; DAS; QH301; Elephant Seal; Elephant Seals; Institut Polaire Français; Kerguelen Islands; Southern Elephant Seal; Southern Elephant Seals
• Online Access: https://hdl.handle.net/10023/19980; https://doi.org/10.1242/jeb.222810

Funding: Fondation BNP Paribas; Centre National d'Etudes Spatiales; Institut Polaire Français Paul Emile Victor; Natural Environment Research Council; H2020 Marie Skłodowska-Curie Actions. Bioluminescence, which occurs in approximately 80% of the world's mesopelagic fauna, can take the form of a low-intensity continuous glow (e.g. for counter-illumination or signalling) or fast repetitions of brighter anti-predatory flashes. The southern elephant seal (SES) is a major consumer of mesopelagic organisms, in particular the abundant myctophid fish, yet the fine-scale relationship between this predator's foraging behaviour and bioluminescent prey remains poorly understood. We hypothesised that brief, intense light emissions should be closely connected with prey strikes when the seal is targeting bioluminescent prey that reacts by emitting anti-predator flashes. To test this, we developed a biologging device containing a fast-sampling light sensor together with location and movement sensors to measure simultaneously anti-predator bioluminescent emissions and the predator's attack motions with a 20 ms resolution. Tags were deployed on female SES breeding at Kerguelen Islands and Península Valdés, Argentina. In situ light levels in combination with duration of prey capture attempts indicated that seals were targeting a variety of prey types. For some individuals, bioluminescent flashes occurred in a large proportion of prey strikes, with the timing of flashes closely connected with the predator's attack motion, suggestive of anti-predator emissions. Marked differences across individuals and location indicate that SES do exploit bioluminescent organisms but the proportion of these in the diet varies widely with location. The combination of wideband light and acceleration data provides new insight into where and when different prey types are encountered and how effectively they might be captured. Peer reviewed