Pelage coloration of breeding crabeater seals Lobodon carcinophaga (Carnivora: Phocidae).

2006 ◽  
Vol 28 (1) ◽  
pp. 93 ◽  
Author(s):  
P. D. Shaughnessy ◽  
R. T. Jones ◽  
P. Ensor
Keyword(s):  
Breeding Sites ◽  
Crabeater Seal ◽  
Pack Ice ◽  
Crabeater Seals ◽  
Aerial Observation ◽  
The Antarctic ◽  
Pelage Coloration

Pelage colouration of the crabeater seal (Lobodon carcinophaga) which occupies the Antarctic pack-ice zone were studied during on breeding sites in the spring (October- November) of 1985 and and 1987. Colour categories for the dorsum and venter graded from silve-white through silver-gery to dark grey and dark brown. Aerial observation over Enderby Land indicated that the males were usually paler than the females. Females, but not males, were commonly dappled on the trunk.

scholarly journals Antarctic Radiocarbon Reservoir: The Case of the Mummified Crabeater Seals (Lobodon Carcinophaga) in Bodman Cape, Seymour Island, Antarctica

Radiocarbon ◽  
2011 ◽  
Vol 53 (1) ◽  
pp. 161-166 ◽  
Author(s):  
Javier Negrete ◽  
Esteban Soibelzon ◽  
Eduardo P Tonni ◽  
Alejandro Carlini ◽  
Leopoldo H Soibelzon ◽  
...  
Keyword(s):  
Geographical Location ◽  
Euphausia Superba ◽  
Death Event ◽  
Pack Ice ◽  
Seal Population ◽  
Antarctic Seals ◽  
Antarctic Continent ◽  
Crabeater Seals ◽  
The Antarctic ◽  
Reservoir Age

At least 50% of the world's seal population is distributed in the pack-ice region surrounding Antarctica. Among the Antarctic seals, Lobodon carcinophaga (commonly known as “crabeater seals”) are the most abundant. This is a krill-feeding species, subsisting primarily on Euphausia superba. The occurrence of mummified seals has been documented since 1900 in several Antarctic regions, and different hypotheses about age and what happened to them have been proposed. Taking into account the depletion of 14C concentration in marine waters, we dated a recently deceased and a mummified L. carcinophaga along with a mollusk (Nacella concinna) collected alive from different locations around Antarctica. We discuss their relationship in light of the 14C reservoir. The age obtained for the recently deceased crabeater seals suggests a reservoir age of around 1300 yr for these waters, which is in agreement with the correction value for reservoir age obtained for the same species in the area. We applied this reservoir correction value to the conventional age of 1180 14C yr BP obtained for the mummified seal. The results indicate that the death event probably occurred within the last 100 yr. The age obtained for the mollusk specimen confirms that the correction values of the reservoir effect for the Antarctic continent vary according to geographical location and to the type of sample dated.

scholarly journals The influence of animal mobility on the assumption of uniform distances in aerial line-transect surveys

2008 ◽  
Vol 35 (4) ◽  
pp. 275 ◽  
Author(s):  
Rachel M. Fewster ◽  
Colin Southwell ◽  
David L. Borchers ◽  
Stephen T. Buckland ◽  
Anthony R. Pople
Keyword(s):  
Survey Design ◽  
Distance Sampling ◽  
High Mobility ◽  
Line Transect ◽  
Transect Line ◽  
Aerial Surveys ◽  
Pack Ice ◽  
Capture Recapture ◽  
Distance Data ◽  
Crabeater Seals

Line-transect distance sampling is a widely used method for estimating animal density from aerial surveys. Analysis of line-transect distance data usually relies on a requirement that the statistical distribution of distances of animal groups from the transect line is uniform. We show that this requirement is satisfied by the survey design if all other assumptions of distance sampling hold, but it can be violated by consistent survey problems such as responsive movement of the animals towards or away from the observer. We hypothesise that problems with the uniform requirement are unlikely to be encountered for immobile taxa, but might become substantial for species of high mobility. We test evidence for non-uniformity using double-observer distance data from two aerial surveys of five species with a spectrum of mobility capabilities and tendencies. No clear evidence against uniformity was found for crabeater seals or emperor penguins on the pack-ice in East Antarctica, while minor non-uniformity consistent with responsive movement up to 30 m was found for Adelie penguins. Strong evidence of either non-uniformity or a failure of the capture–recapture validating method was found for eastern grey kangaroos and red kangaroos in Queensland.

scholarly journals Albedo of the ice covered Weddell and Bellingshausen Seas

2012 ◽  
Vol 6 (2) ◽  
pp. 479-491 ◽  
Author(s):  
A. I. Weiss ◽  
J. C. King ◽  
T. A. Lachlan-Cope ◽  
R. S. Ladkin
Keyword(s):  
Sea Ice ◽  
Surface Albedo ◽  
Austral Summer ◽  
Open Water ◽  
Weddell Sea ◽  
First Year ◽  
Pack Ice ◽  
Bellingshausen Sea ◽  
The Mean ◽  
The Antarctic

Abstract. This study investigates the surface albedo of the sea ice areas adjacent to the Antarctic Peninsula during the austral summer. Aircraft measurements of the surface albedo, which were conducted in the sea ice areas of the Weddell and Bellingshausen Seas show significant differences between these two regions. The averaged surface albedo varied between 0.13 and 0.81. The ice cover of the Bellingshausen Sea consisted mainly of first year ice and the sea surface showed an averaged sea ice albedo of αi = 0.64 ± 0.2 (± standard deviation). The mean sea ice albedo of the pack ice area in the western Weddell Sea was αi = 0.75 ± 0.05. In the southern Weddell Sea, where new, young sea ice prevailed, a mean albedo value of αi = 0.38 ± 0.08 was observed. Relatively warm open water and thin, newly formed ice had the lowest albedo values, whereas relatively cold and snow covered pack ice had the highest albedo values. All sea ice areas consisted of a mixture of a large range of different sea ice types. An investigation of commonly used parameterizations of albedo as a function of surface temperature in the Weddell and Bellingshausen Sea ice areas showed that the albedo parameterizations do not work well for areas with new, young ice.

New records of mummified crabeater seals on islands bordering Admiralty Sound, Weddell Sea

2019 ◽  
Vol 31 (3) ◽  
pp. 109-115
Author(s):  
Javier Negrete ◽  
Leopoldo H. Soibelzon ◽  
Esteban Soibelzon ◽  
Jorge Lusky
Keyword(s):  
Open Water ◽  
Weddell Sea ◽  
Pack Ice ◽  
Breeding Grounds ◽  
Ice Conditions ◽  
Crabeater Seals ◽  
Ice Floes ◽  
Early Breakup ◽  
Natural Trap ◽  
Seymour Island

AbstractNinety-six mummified crabeater seals discovered at Seymour Island (Isla Marambio) are reported. Each specimen was georeferenced, photographed and assigned to five different taphonomic states. Previous work stated that seals at Seymour Island get stranded inland around the breeding season. However, it is not clear if the species breeds in this area. The abundance of crabeater seals and the ice condition along Admiralty Sound (Estrecho Bouchard) were obtained by aerial surveys during spring (2015–17). It appears that the species uses the strait as a passage to breeding grounds. Under heavy ice conditions, the seals become stranded in the middle section of this strait and wander inland through a valley that represents the mouth of an ephemeral stream that ends at the pack ice level. This situation was observed in 2014 and 2015 when recently dead seals were found, evidencing that this natural trap is still active. Nonetheless, in 2016 and 2017, during an early breakup of Admiralty Sound, the seals that remained in the area were more numerous than in 2015 but they did not get stranded inland. This early breakup may encourage the seals to breed there in the presence of open water areas with ice floes.

The occurrence of the copepods Stephos longipes (Calanoida) and Drescheriella glacialis (Harpacticoida) in summer sea ice in the Weddell Sea, Antarctica

2001 ◽  
Vol 13 (2) ◽  
pp. 150-157 ◽  
Author(s):  
Sigrid B. Schnack-Schiel ◽  
David N. Thomas ◽  
Christian Haas ◽  
Gerhard S. Dieckmann ◽  
Ruth Alheit
Keyword(s):  
Total Population ◽  
Calanoid Copepod ◽  
Late Summer ◽  
Geographic Area ◽  
Weddell Sea ◽  
Air Temperatures ◽  
Pack Ice ◽  
Stephos Longipes ◽  
Surface Ice ◽  
The Antarctic

In January to March 1997, a RV Polarstern cruise that transected the Weddell Sea resulted in samples being taken in thick pack ice in the south-eastern Weddell Sea and then along the marginal ice edge towards the Antarctic Peninsula. Several ice types were thus sampled over a wide geographic area during late summer/early autumn. Common features of the first warm period was the occurrence of surface ponds, and that many floes had quasi-continuous horizontal gaps, underlying a layer of ice and metamorphic snow. With the onset of cold air temperatures in late February the gaps rapidly refroze. The calanoid copepod Stephos longipes occurred in all habitats encountered and showed highest numbers in the surface ice in summer, in the gap water during both seasons and in the refrozen gap water in autumn. Nauplii outnumbered copepodids in the surface ice and refrozen gap water, while in the gap water copepodids, mainly stages CI–CIII in summer and CII–CIV in autumn, comprised about 70% of the total population. The harpacticoid species Drescheriella glacialis did not occur in all habitats and was missing in surface ponds and new ice. Nauplii of D. glacialis were rarely found in gap water, but predominated in the refrozen gaps.

Projected shifts in the foraging habitat of crabeater seals along the Antarctic Peninsula

2020 ◽  
Vol 10 (5) ◽  
pp. 472-477 ◽  
Author(s):  
Luis A. Hückstädt ◽  
Andrea Piñones ◽  
Daniel M. Palacios ◽  
Birgitte I. McDonald ◽  
Michael S. Dinniman ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Foraging Habitat ◽  
Crabeater Seals ◽  
The Antarctic

Bird and mammal life recorded during the Antarctic drift of SY Aurora, 1915–16

Polar Record ◽  
1990 ◽  
Vol 26 (159) ◽  
pp. 277-288 ◽  
Author(s):  
P. D. Shaughnessy
Keyword(s):  
Southern Ocean ◽  
Ross Sea ◽  
Killer Whales ◽  
Food Items ◽  
Emperor Penguins ◽  
Sea Birds ◽  
Pack Ice ◽  
Antarctic Expedition ◽  
The Antarctic ◽  
Blue Whales

AbstractAfter landing the Ross Sea shore party of Shackleton's Imperial Trans-Antarctic Expedition at Cape Evans, McMurdo Sound, SY Aurora drifted for 313 days between May 1915 and March 1916 in the pack iceof the Ross Sea and Southern Ocean. During the drift A. H. Ninnis maintained observations of the fauna. He was out hunting on the pack ice on at least 86 days to augment the ship's slender provisions, taking 289 penguins, 10 other sea birds and 20 seals. He sighted whales on at least 15 days, including killer whales in July and August and four large whales, possibly blue whales, in November. He also noted birds returning south for the breeding season in spring, progress of moult in emperor penguins, pupping of crabeater and leopard seals, and food items of several seals and seabirds. Most of his report is presented here, edited to improve its readability and remove abbreviations; the text is preceded by a brief summary of the fauna seen and followed by footnotes on some of his observations.

Reproductive aspects of female crabeater seals (Lobodon carcinophagus) along the Antarctic Peninsula

1981 ◽  
Vol 59 (1) ◽  
pp. 92-102 ◽  
Author(s):  
John L. Bengtson ◽  
Donald B. Siniff
Keyword(s):  
Antarctic Peninsula ◽  
Reproductive Performance ◽  
Sexual Maturity ◽  
Marine Ecosystem ◽  
Geographical Differences ◽  
The Past ◽  
Antarctic Marine ◽  
Crabeater Seals ◽  
Lobodon Carcinophagus ◽  
The Antarctic

Examination of a sample of 94 female crabeater seals collected in November, 1977, indicated that, for the past 7 years, the average age at sexual maturity was 3.8 years. Reproductive performance as evidenced by uterine scars and ovarian corpora is discussed. No females inseminated at age 4 or less successfully carried a fetus full term. Timing of ovulation was affected by both age and social category. Younger seals ovulate later in the season than older seals. No females ovulated prior to weaning their pups. Ovulation in experienced females occurred sometimes while still in a mated pair, but mostly at or after dissolution of the pair bond. Comparison of recent age of sexual maturity with earlier reports shows an increase in this age since 1967. This trend may reflect geographical differences or changes in the Antarctic marine ecosystem following a slowdown in Antarctic whaling.

The Antarctic Pack-Ice Ecosystem

BioScience ◽  
1995 ◽  
Vol 45 (3) ◽  
pp. 128-132 ◽  
Author(s):  
Jane E. Stevens
Keyword(s):  
Pack Ice ◽  
The Antarctic

Estimating population status under conditions of uncertainty: the Ross seal in East Antarctica

2008 ◽  
Vol 20 (2) ◽  
pp. 123-133 ◽  
Author(s):  
Colin J. Southwell ◽  
Charles G.M. Paxton ◽  
David L. Borchers ◽  
Peter L. Boveng ◽  
Erling S. Nordøy ◽  
...  
Keyword(s):  
Survey Design ◽  
East Antarctica ◽  
Population Status ◽  
Pack Ice ◽  
The Status ◽  
Antarctic Treaty ◽  
Survey Design And Analysis ◽  
The Many ◽  
Many Sources ◽  
The Antarctic

AbstractThe Ross seal (Ommatophoca rossii) is the least studied of the Antarctic ice-breeding phocids. In particular, estimating the population status of the Ross seal has proved extremely difficult. The Protocol on Environmental Protection to the Antarctic Treaty currently designates the Ross seal as a ‘Specially Protected Species’, contrasting with the IUCN's classification of ‘Least Concern’. As part of a review of the Ross seal's classification under the Protocol, a survey was undertaken in 1999/2000 to estimate the status of the Ross seal population in the pack ice off East Antarctica between 64–150°E. Shipboard and aerial sighting surveys were carried out along 9476 km of transect to estimate the density of Ross seals hauled out on the ice, and satellite dive recorders deployed on a sample of Ross seals to estimate the proportion of time spent on the ice. The survey design and analysis addressed the many sources of uncertainty in estimating the abundance of this species in an effort to provide a range of best and plausible estimates. Best estimates of abundance in the survey region ranged from 41 300–55 900 seals. Limits on plausible estimates ranged from 20 500 (lower 2.5 percentile) to 226 600 (upper 97.5 percentile).

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