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Proceedings of OceanObs'09: Sustained Ocean Observations and Information for Society

COMMUNITY WHITE PAPER10.5270/OceanObs09.cwp.15

New Insights into Southern Ocean Physical and Biological Processes Revealed by Instrumented Elephant Seals

J.-B. Charrassin(1), F. Roquet(1), Y.-H. Park(1), F. Bailleul(2), C. Guinet(2), M. Meredith(3), K. Nicholls(3), S. Thorpe(3), B. McDonald(4), D.P. Costa(4), I. Tremblay(5), M. Goebel(6), M. Muelbert(7), M.N. Bester(8), J. Plötz (9), H. Bornemann(10), R. Timmermann (11), M. Hindell(12), A. Meijers(13), R.C. Coleman(13), I.C. Field(14), C.R. McMahon(15), S.R. Rintoul(16), S. Sokolov(16), L. Boehme(17), P. Lovell(17), M.A. Fedak(17), M. Biuw(18), O.A. Nost(18), C. Lydersen(18), K.M. Kovacs(18)

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In recent years, the international "Southern Elephant seals as Oceanographic Samplers" (SEaOS) project has deployed miniaturized conductivity-temperature-depth satellite-relayed data loggers (CTD-SRDL) on elephant seals 1) to study their winter foraging ecology in relation to oceanographic conditions, and 2) to collect hydrographic data from polar regions, which are otherwise sparsely sampled. We summarize here the main results that have been published in both science components since 2003/2004. Instrumented southern elephant seals visit different regions within the Southern Ocean (frontal zones, continental shelf, and/or ice covered areas) and forage in a variety of different water masses (e.g. Circumpolar Deep Water upwelling regions, High Salinity Shelf Water), depending on their geographic distribution. Adult females and juvenile males from Kerguelen Is. forage pelagically in frontal zones of the Southern Indian Ocean, while adult males forage benthically over the Kerguelen Plateau and the Antarctic Continental Shelf, with the two groups feeding at different trophic levels as shown by stable isotopes analysis. Oceanographic studies using the data collected from the seals have, to date, concentrated on circumpolar and regional studies of the Antarctic Circumpolar Current (ACC) circulation. The temperature and salinity profiles documented by elephant seals at high latitudes, including below sea ice, have permitted quasi-circumpolar mapping of the southernmost fronts of the ACC. By merging conventional data and the high temporal and spatial resolution data collected by seal-borne SRDLs, it has been possible to describe precisely 1) the large-scale features of the ACC in the South Atlantic and its variability; 2) the circulation pattern over the Kerguelen plateau, revealing that the poorly known Fawn Trough concentrates an important proportion of the ACC flow in that region. Seals that foraged in ice covered areas have made eulerian time series available that have allowed for the estimation of sea ice formation rates, a parameter that is otherwise difficult to obtain, while also providing a unique description of the wintertime ocean circulation over the central Weddell Sea continental shelf. Finally, we present the first data collected by a newly-developed fluorescence sensor that has been embedded in the regular CTD-SRDL and deployed on elephant seals at Kerguelen. The fluorometer data obtained have offered the first synoptic view of the 3 dimensional distribution of temperature, salinity and fluorescence over a vast sector of the Southern Indian Ocean, allowing us to describe both vertical and horizontal variations in chlorophyll. This paper will make a core contribution to the Plenary Sessions 2C, 3A and 4A, and will be relevant to 2A and 2B.

1LOCEAN (Laboratoire d'Océanographie et du Climat: Expérimentations et approches numériques)/Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris Cedex 05 France
2Centre d'Etudes Biologiques de Chizé, CNRS (Centre National de la Recherche Scientifique), BP 14, F-79360 Villiers-en-Bois, France
3British Antarctic Survey, High Cross, Madingley Rd, Cambridge CB3 0ET, United Kingdom
4Center for Ocean Health, Institute of Marine Sciences, Long Marine Lab, University of California, 100 Shaffer Rd., Santa Cruz, CA 95060, USA
5Centre de Recherche Halieutique Méditerranéenne et Tropicale/Institut de Recherche pour le Développement (IRD), Avenue Jean Monnet, BP 171, 34203 Sète Cedex, France
6Antarctic Ecosystem Research Division/NOAA (National Oceanic and Atmospheric Administration), National Marine Fisheries Service, 8604 La Jolla Shores Drive, La Jolla, CA 92037-1508, USA
7PPGOB (Programa de Pós-graduação em Oceanografia Biológica) - Instituto de Oceanografia, Universidade Federal do Rio Grande, Caixa Postal 474, 96201-900 Rio Grande, RS Brasil
8Mammal Research Institute, Department of Zoology & Entomology, School of Biological Sciences, University of Pretoria, Pretoria 0002, South-Africa
9Alfred Wegener Institute, Columbusstrasse, D-27568 Bremerhaven, Germany
10Alfred Wegener Institute for Polar and Marine Research, P.O. Box 12 01 61, 27515 Bremerhaven, Germany
11Alfred Wegener Institute, Bussestrasse 24, D-27570 Bremerhaven, Germany
12Antarctic Wildlife Research Unit, University of Tasmania, PO Box 252-05, Hobart, TAS 7001, Australia
13Center for Marine Science, University of Tasmania, Private Bag 78, Hobart, TAS 7001, Australia
14Marine Mammal Research Group, Graduate School of the Environment, Macquarie University, Sydney, NSW 2109, Australia
15School for Environmental Research, Charles Darwin University, Darwin NT 0909, Australia
16CSIRO (Commonwealth Scientific and Industrial Research Organisation) Wealth from Oceans National Research Flagship and Antarctic Climate and Ecosystems Cooperative Research Centre, Hobart, TAS 7001, Australia
17Sea Mammal Research Unit (SMRU)/Gatty Marine Laboratory, University of St Andrews, St Andrews, Fife KY16 8LB, United Kingdom
18Norwegian Polar Institute, Polar Environmental Centre, Fram Centre, Hjalmar Johansens, gt. 14, NO-9296 Tromsø Norway

Correspondence should be addressed to E-mail: jbc@mnhn.fr

This paper shall be cited as:

Charrassin, J. & Co-Authors (2010). "New Insights into Southern Ocean Physical and Biological Processes Revealed by Instrumented Elephant Seals" in Proceedings of OceanObs’09: Sustained Ocean Observations and Information for Society (Vol. 2), Venice, Italy, 21-25 September 2009, Hall, J., Harrison, D.E. & Stammer, D., Eds., ESA Publication WPP-306, doi:10.5270/OceanObs09.cwp.15

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