[MARMAM] New paper on foraging behaviour of Weddell seals in the southern Weddell Sea

Dominik Nachtsheim d.nachtsheim at outlook.de
Sun Mar 10 14:02:16 PDT 2019

Dear MARMAM readers,

we are pleased to announce the publication of the following article in Progress in Oceanography:

Nachtsheim, D.A., Ryan, S., Schröder, M., Jensen, L., Oosthuizen, W.C., Bester, M.N., Hagen, W. and Bornemann, H., 2019. Foraging behaviour of Weddell seals (Leptonychotes weddellii) in connection to oceanographic conditions in the southern Weddell Sea. Progress in Oceanography 173, 165-179. doi:10.1016/j.pocean.2019.02.013

The region of the Filchner Outflow System (FOS) in the southeastern Weddell Sea is characterized by intensive and complex interactions of different water masses. Dense Ice Shelf Water (ISW) emerging from beneath the ice shelf cavities on the continental shelf, meets Modified Warm Deep Water (MWDW) originating from the Antarctic Circumpolar Current at the sill of the Filchner Trough. These hydrographic features convert the FOS into an oceanographic key region, which may also show enhanced biological productivity and corresponding aggregations of marine top predators. In this context, six adult Weddell seals (Leptonychotes weddellii) were instrumented with CTD-combined satellite relay data loggers in austral summer 2014. By means of these long-term data loggers we aimed at investigating the influence of environmental conditions on the seals’ foraging behaviour throughout seasons, focussing on the local oceanographic features. Weddell seals performed pelagic and demersal dives, mainly on the continental shelf, where they presumably exploited the abundant bentho-pelagic fish fauna. Diurnal and seasonal variations in light availability affected foraging activities. MWDW was associated with increased foraging effort. However, we observed differences in movements and habitat use between two different groups of Weddell seals. Seals tagged in the pack ice of the FOS focussed their foraging activities to the western and, partly, eastern flank of the Filchner Trough, which coincides with inflow pathways of MWDW. In contrast, Weddell seals tagged on the coastal fast ice exhibited typical central-place foraging and utilized resources close to their colony. High foraging effort in MWDW and high utilization of areas associated with an inflow of MWDW raise questions on the underlying biological features. This emphasizes the importance of further interdisciplinary ecological investigations in the near future, as the FOS may soon be impacted by predicted climatic changes.

The paper can be accessed and downloaded freely under the following link: https://www.sciencedirect.com/science/article/pii/S0079661118301216

If you have any questions or inquiries, do not hesitate to contact me directly!

All the best on behalf of all authors,
Dominik Nachtsheim

Dominik A. Nachtsheim, M.Sc.
University of Veterinary Medicine Hannover, Foundation
Institute for Terrestrial and Aquatic Wildlife Research (ITAW)
Werftstr. 6
25761 Büsum

Dominik.Nachtsheim at tiho-hannover.de
Tel:  +49 511 856-8159
Fax: +49 511 856-8181

ResearchGate: https://www.researchgate.net/profile/Dominik_Nachtsheim
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