The diet of the Antarctic fur seal Arctocephalus gazella at the South Orkney Islands in ten consecutive years

AbstractThe dense water outflow from the Antarctic continental shelf is closely associated with the strength and position of the Antarctic Slope Front. This study explores the short-term and spatial variability of the Antarctic Slope Front system and the mechanisms that regulate cross-slope exchange using highly temporally and spatially resolved measurements from three ocean gliders deployed in 2012. The 22 sections along the eastern Antarctic Peninsula and west of the South Orkney Islands are grouped regionally and composited by isobaths. There is consistency in the front position around the Powell Basin, varying mostly between the 500- and 800-m isobaths. In most of the study area the flow is bottom intensified. The along-slope transport of the Antarctic Slope Current (upper 1000 m) varies between 0.2 and 5.9 Sv (1 Sv ≡ 106 m3 s−1) and does not exhibit a regional pattern. The magnitude of the velocity field shows substantial variability, up to twice its mean value. Higher eddy kinetic energy (0.003 m2 s−2) is observed in sections with dense water, possibly because of baroclinic instabilities in the bottom layer. Distributions of potential vorticity show an increase toward the shelf along isopycnals and also in the dense water layer. Glider sections located west of the South Orkney Islands indicate a northward direction of the flow associated with the Weddell Front, which differs from previous estimates of the mean circulation. This study provides some of the first observational confirmation of the high-frequency variability associated with an active eddy field that has been suggested by recent numerical simulations in this region.

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Changes in plasma progesterone and prolactin concentrations during the annual cycle and the role of prolactin in the maintenance of lactation and luteal development in the Antarctic fur seal (Arctocephalus gazella)

Reproduction ◽

10.1530/jrf.0.0910637 ◽

1991 ◽

Vol 91 (2) ◽

pp. 637-647 ◽

Cited By ~ 37

Author(s):

I. L. Boyd

Keyword(s):

Annual Cycle ◽

Arctocephalus Gazella ◽

Plasma Progesterone ◽

Antarctic Fur Seal ◽

Fur Seal ◽

The Antarctic

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Fur seal skull from sealers' quarters at Sandy Bay, Macquarie Island, Southern Ocean

Polar Record ◽

10.1017/s0032247400012651 ◽

1991 ◽

Vol 27 (162) ◽

pp. 245-248 ◽

Cited By ~ 1

Author(s):

K. Townrow ◽

P. D. Shaughnessy

Keyword(s):

Southern Ocean ◽

Arctocephalus Gazella ◽

Archaeological Excavation ◽

Antarctic Fur Seal ◽

Macquarie Island ◽

Fur Seals ◽

Fur Seal ◽

Antarctic Research ◽

The Antarctic ◽

Specific Identity

AbstractFur seals were exterminated from Macquarie Island about 20 years after discovery of the island in 1810. Their specific identity is unknown. Few fur seals were reported at the island until it was occupied by the Australian National Antarctic Research Expeditions in 1948. Fur seal numbers are now increasing. An archaeological excavation at a sealers' quarters at Sandy Bay in 1988 revealed the fragmented skull of a young Antarctic fur sealArctocephalus gazella1.1 m below the surface in a layer dated in the 1870s and 1880s. This period coincides with the recovery of fur seal populations in the South Atlantic Ocean following earlier harvesting. Elsewhere it has been argued that the Antarctic fur seal is unlikely to have been the original fur seal at Macquarie Island because few individuals of that species are ashore in winter, which is the season when the island was discovered and fur-seal harvesting began. It is concluded that the Sandy Bay skull is from a vagrant animal.

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Dispersal of male and female Antarctic fur seals (Arctocephalus gazella)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f97-314 ◽

1998 ◽

Vol 55 (4) ◽

pp. 845-852 ◽

Cited By ~ 79

Author(s):

I L Boyd ◽

D J McCafferty ◽

K Reid ◽

R Taylor ◽

T R Walker

Keyword(s):

Arctocephalus Gazella ◽

Adult Males ◽

The South ◽

Male And Female ◽

Breeding Sites ◽

South Georgia ◽

Orkney Islands ◽

Fur Seals ◽

South Orkney Islands ◽

Antarctic Fur Seals

This study examined the foraging locations of adult male and female Antarctic fur seals (Arctocephalus gazella) in the Scotia Sea during the postbreeding period. Satellite transmitters were used to track adult males and females and to obtain information about dive depths. Male fur seals migrated away from the breeding area during the postbreeding period whereas females remained close to the breeding grounds and foraged in the same area during two consecutive years. The most intensive foraging by females was associated with the edge of the continental shelf of South Georgia. Males dived deeper than females. Counts of males at South Georgia and at the South Orkney Islands support the result from satellite tracking data showing that males move from South Georgia to the South Orkney Islands at the end of the breeding season. Unlike males, females were limited in their foraging range by the necessity to return to feed dependent young, so breeding sites are likely to be located close to foraging areas that are optimal for females. Locations used for feeding by females were avoided by males, either because they were suboptimal for males or because foraging by females at South Georgia causes local depletion of food, and males, which have the option to forage further afield, can forage more successfully in regions where there are no females. Comparison with fisheries data also suggests that these fur seals are targeting the most abundant exploitable prey.

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A new macroflora from the South Orkney Islands, Antarctica: evidence of an Early to Middle Jurassic age for the Powell Island Conglomerate

Antarctic Science ◽

10.1017/s0954102000000249 ◽

2000 ◽

Vol 12 (2) ◽

pp. 185-195 ◽

Cited By ~ 15

Author(s):

David J. Cantrill

Keyword(s):

Antarctic Peninsula ◽

Middle Jurassic ◽

Initial Phase ◽

The South ◽

Orkney Islands ◽

Continental Deposits ◽

Geological Evolution ◽

South Orkney Islands ◽

Break Up ◽

The Antarctic

A macroflora from John Peaks, Powell Island, contains Sagenopteris nilssoniana, Cladophlebis oblonga, Brachyphyllum sp., Elatocladus confertus, and Sphenopteris sp. The macroflora is best correlated with the Botany Bay Group flora, suggesting an Early to Middle Jurassic age for the Powell Island Conglomerate. This age supports new interpretations for the geological evolution of the Antarctic Peninsula that suggest the initial phase of Gondwana break-up was manifested as small rift grabens with continental deposits.

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The cryptostigmatid mite Halozetes belgicae (Michael) in the maritime Antarctic

Antarctic Science ◽

10.1017/s0954102091000093 ◽

1991 ◽

Vol 3 (1) ◽

pp. 53-59 ◽

Cited By ~ 4

Author(s):

L.B. Minto ◽

G.J. Shepherd ◽

M.B. Usher

Keyword(s):

South Shetland Islands ◽

Maritime Antarctic ◽

The South ◽

Macquarie Island ◽

Shetland Islands ◽

Orkney Islands ◽

South Orkney Islands ◽

South Sandwich Islands ◽

The Antarctic ◽

Morphometrical Study

Halozetes belgicae is distributed widely in the Subantarctic and maritime Antarctic, with subspecies described from Macquarie Island and the South Sandwich Islands. A morphometrical study, based largely on the development of the setae, indicates that the nominate subspecies is confined to the Antarctic Peninsula and its offshore islands (including the South Shetland Islands), whilst specimens from the South Orkney Islands are probably consubspecific with individuals on the South Sandwich Islands. In comparison with other studies of the Acari, the results strengthen the case for the recognition of a South Orkadian biogeographical zone.

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