Habitat-based density models of pack-ice seal distribution in the southern Weddell Sea, Antarctica
Habitat-based density models of pack-ice seal distribution in the southern Weddell Sea, Antarctica
Climate variability and changes in sea ice dynamics have caused several ice-obligate or krill-dependent populations of marine predators to decline, eliciting concern about their demographic persistence and the indirect ecological consequences that predator depletions may have on marine ecosystems. Pack-ice seals are dominant ice-obligate predators in the Antarctic marine ecosystem, but there is considerable uncertainty about their abundance and population trends. We modelled the density and distribution of pack-ice seals as a function of environmental covariates in the southern Weddell Sea, Antarctica. Our density surface modelling approach used data from aerial surveys of pack-ice seals collected in the 2013/14 austral summer. Crabeater seals Lobodon carcinophaga, the most numerous pack-ice seal we observed, occurred at the highest densities in areas with extensive sea ice near the continental shelf break, but were almost absent in areas of similar sea ice concentration in the southern extent of the Weddell Sea. The highest densities of Weddell seals Leptonychotes weddelli, which were less abundant than crabeater seals within the pack-ice habitat, were predicted to occur over the continental shelf, near the shelf break. The distribution of both seal species broadly corresponded with the distribution and relative abundance of their main prey (Antarctic krill Euphausia superba and Antarctic silverfish Pleuragramma antarctica) obtained from concurrent ecosystem surveys. Ross seals Ommatophoca rossii and leopard seals Hydrurga leptonyx were not detected at all and are apparently rare within the southern Weddell Sea. These results can contribute to biodiversity assessments in the context of marine protected area planning in this region of the Southern Ocean.
Crabeater seal, Density surface model, Distance sampling, Euphausia superba, Filchner Trough, Marine predator, Pleuragramma antarctica, Weddell seal
211-227
Oosthuizen, W.C.
1b94648f-2c36-4d46-bc75-ca5b394a3f98
Reisinger, R.R.
4eaf9440-48e5-41fa-853f-d46457e5444e
Bester, M.N.
db851c58-bc19-432a-be7c-4c3e59aec6ab
Steinhage, D.
9f609364-d991-44ed-a18c-0517f66b4879
Auel, H.
dabc86d5-bc00-470b-9921-4567dddc864d
Flores, H.
dba533f3-437a-47c7-bf9e-5025fc2f732c
Knust, R.
fe704355-c9fa-49d7-9ee1-991667a7ab35
Ryan, S.
df133b98-ee8e-44e6-a4ea-3a829fe4d102
Bornemann, H.
e307bef5-4704-4ea3-bc88-0b1893cb3584
2 September 2021
Oosthuizen, W.C.
1b94648f-2c36-4d46-bc75-ca5b394a3f98
Reisinger, R.R.
4eaf9440-48e5-41fa-853f-d46457e5444e
Bester, M.N.
db851c58-bc19-432a-be7c-4c3e59aec6ab
Steinhage, D.
9f609364-d991-44ed-a18c-0517f66b4879
Auel, H.
dabc86d5-bc00-470b-9921-4567dddc864d
Flores, H.
dba533f3-437a-47c7-bf9e-5025fc2f732c
Knust, R.
fe704355-c9fa-49d7-9ee1-991667a7ab35
Ryan, S.
df133b98-ee8e-44e6-a4ea-3a829fe4d102
Bornemann, H.
e307bef5-4704-4ea3-bc88-0b1893cb3584
Oosthuizen, W.C., Reisinger, R.R., Bester, M.N., Steinhage, D., Auel, H., Flores, H., Knust, R., Ryan, S. and Bornemann, H.
(2021)
Habitat-based density models of pack-ice seal distribution in the southern Weddell Sea, Antarctica.
Marine Ecology Progress Series, 673, .
(doi:10.3354/MEPS13787).
Abstract
Climate variability and changes in sea ice dynamics have caused several ice-obligate or krill-dependent populations of marine predators to decline, eliciting concern about their demographic persistence and the indirect ecological consequences that predator depletions may have on marine ecosystems. Pack-ice seals are dominant ice-obligate predators in the Antarctic marine ecosystem, but there is considerable uncertainty about their abundance and population trends. We modelled the density and distribution of pack-ice seals as a function of environmental covariates in the southern Weddell Sea, Antarctica. Our density surface modelling approach used data from aerial surveys of pack-ice seals collected in the 2013/14 austral summer. Crabeater seals Lobodon carcinophaga, the most numerous pack-ice seal we observed, occurred at the highest densities in areas with extensive sea ice near the continental shelf break, but were almost absent in areas of similar sea ice concentration in the southern extent of the Weddell Sea. The highest densities of Weddell seals Leptonychotes weddelli, which were less abundant than crabeater seals within the pack-ice habitat, were predicted to occur over the continental shelf, near the shelf break. The distribution of both seal species broadly corresponded with the distribution and relative abundance of their main prey (Antarctic krill Euphausia superba and Antarctic silverfish Pleuragramma antarctica) obtained from concurrent ecosystem surveys. Ross seals Ommatophoca rossii and leopard seals Hydrurga leptonyx were not detected at all and are apparently rare within the southern Weddell Sea. These results can contribute to biodiversity assessments in the context of marine protected area planning in this region of the Southern Ocean.
This record has no associated files available for download.
More information
Published date: 2 September 2021
Additional Information:
Funding Information: we thank Captain Stefan Schwarze and the officers and crew of RV 'Polarstern'; helicopter pilots Lars Vaupel, Michael Gischler and the HeliService International team; the crew of 'Polar6' (Dean Emberley, John Gilmour and Roger Hudon, all from Kenn Borek Air); Martina Vortkamp and the RV 'Polarstern' scientific teams; and staff of the Department Logistics and Research Platforms of the Alfred-Wegener-Institute (AWI), Helmholtz-Zentrum für Polar- und Meeresforschung, Germany, for their outstanding support during the expedition PS82. This study was supported by Grant No. AWI_PS82_03, the Helmholtz Association Research Programme Polar regions And Coasts in the changing Earth System II (PACES II), Topic 1, WP 5 and WP 6, and is part of the Helmholtz Association Young Investigators Groups Iceflux: Ice-ecosystem carbon flux in polar oceans (VH-NG-800). Write-up of this work was furthermore supported by a National Research Foundation (NRF) of South Africa postdoctoral grant to W.C.O., Hanse-Wissenschaftskolleg (Delmenhorst, Germany) fellowships to W.C.O. and M.N.B. and an AWI fellowship to W.C.O.
Keywords:
Crabeater seal, Density surface model, Distance sampling, Euphausia superba, Filchner Trough, Marine predator, Pleuragramma antarctica, Weddell seal
Identifiers
Local EPrints ID: 487092
URI: http://eprints.soton.ac.uk/id/eprint/487092
ISSN: 0171-8630
PURE UUID: 5d2f7fe3-4278-4c77-aec7-86b639b25c46
Catalogue record
Date deposited: 13 Feb 2024 17:32
Last modified: 18 Mar 2024 04:03
Export record
Altmetrics
Contributors
Author:
W.C. Oosthuizen
Author:
M.N. Bester
Author:
D. Steinhage
Author:
H. Auel
Author:
H. Flores
Author:
R. Knust
Author:
S. Ryan
Author:
H. Bornemann
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics
