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Combining bio-logging and fatty acid signature analysis indicates spatio-temporal variation in the diet of the southern elephant seal, Mirounga leonina

Combining bio-logging and fatty acid signature analysis indicates spatio-temporal variation in the diet of the southern elephant seal, Mirounga leonina
Janaya Banks

Authors

Banks J
Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania

Lea M
Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania

McMahon C
Research Institute for the Environment and Livelihoods, Charles Darwin University

Hindell M
Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania

Abstract

Quantifying the foraging ecology of apex predators is crucial for understanding and managing marine ecosystems. This is particularly important in the Southern Ocean ecosystem, as its vastness and heterogeneously distributed biological resources make year-round studies logistically impractical. Moreover, due to the wide-ranging nature of many southern hemisphere marine predators, detailed investigations into their diet need to be quantified spatio-temporally. We coupled tracking data with fatty acid signature analysis to investigate the foraging ecology of the southern elephant seal (Mirounga leonina). Seal foraging areas varied in space and time, but were concentrated in three broad geographic regions (i) off the East Antarctic Continental Shelf (S-ACC), (ii) at the edge of the pack ice north of the Ross Sea (SE-RS) and (iii) north of the Sub-Antarctic Front (SE-SAF). There were significant differences in the fatty acids (FA) in the blubber from the seals that used these different regions. Those in the SE-SAF were high in short chained mono-unsaturated fatty acids, compared to those from the S-ACC and SE-RS habitats, which contained more poly-unsaturated fatty acids. Comparisons with FAs of known prey species from the region indicated that blubber collected from seals using the shelf and pack-ice habitats were likely to have higher proportions of fish in the diet and, conversely, those from pelagic habitats were likely to have higher proportions of squid. Diet also varied annually, within the shelf and pack-ice habitats changing from a diet relatively high in fish, to a diet relatively high in squid. Coupling tracking data with FASA is a powerful technique to investigate the spatio-temporal variations in the diet of a wide-ranging marine predator, the southern elephant seal.

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This page was last modified on 5 September 2013.