scholarly journals Age, geographical distribution and taphonomy of an unusual occurrence of mummified crabeater seals on James Ross Island, Antarctic Peninsula

2008 ◽  
Vol 20 (5) ◽  
pp. 485-493 ◽  
Author(s):  
A.E. Nelson ◽  
J.L. Smellie ◽  
M. Williams ◽  
S. Moreton
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Open Water ◽  
Phocine Distemper Virus ◽  
James Ross Island ◽  
Unusual Occurrence ◽  
Crabeater Seals ◽  
Western Side ◽  
The Antarctic ◽  
North Western

AbstractAn unusually dense collection of some 150 dead crabeater seals (Family Phocidae), in various stages of decay, occurs in the Brandy Bay hinterland, north-western James Ross Island, northern Antarctic Peninsula. Throughout the past 100 years, the presence of shelf ice (no longer present today) and sea ice in Prince Gustav Channel, between James Ross Island and the Antarctic Peninsula, has prevented seals from readily accessing the western side of James Ross Island. However, open water pools, some over one kilometre in diameter, remain accessible throughout the winter months, allowing seals to haul out onto the ice. It is likely that some of these seals may become disorientated as they wander away from the pools and instead head toward Brandy Bay and onto low-lying and snow-covered Abernethy Flats, easily mistaken for sea ice in early winter, where they perish. The large number of variably-decayed animals present suggests that this has probably happened on numerous occasions. However, some of the dead seals also probably perished during a documented mass dying event of crabeater seals in Prince Gustav Channel caused by an unidentified epidemic, possibly phocine distemper virus (PDV), during the spring of 1955.

Temperature Change on the Antarctic Peninsula Linked to the Tropical Pacific*

2013 ◽  
Vol 26 (19) ◽  
pp. 7570-7585 ◽  
Author(s):  
Qinghua Ding ◽  
Eric J. Steig
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Large Scale ◽  
Wave Train ◽  
Warming Trend ◽  
Tropical Pacific ◽  
The West ◽  
Spring Warming ◽  
Western Side ◽  
The Antarctic

Abstract Significant summer warming over the eastern Antarctic Peninsula in the last 50 years has been attributed to a strengthening of the circumpolar westerlies, widely believed to be anthropogenic in origin. On the western side of the peninsula, significant warming has occurred mainly in austral winter and has been attributed to the reduction of sea ice. The authors show that austral fall is the only season in which spatially extensive warming has occurred on the Antarctic Peninsula. This is accompanied by a significant reduction of sea ice cover off the west coast. In winter and spring, warming is mainly observed on the west side of the peninsula. The most important large-scale forcing of the significant widespread warming trend in fall is the extratropical Rossby wave train associated with tropical Pacific sea surface temperature anomalies. Winter and spring warming on the western peninsula reflects the persistence of sea ice anomalies arising from the tropically forced atmospheric circulation changes in austral fall.

scholarly journals Diatoms (Bacillariophyta) associated with lichens from Ulu Peninsula (James Ross Island, NE Antarctic Peninsula)

2018 ◽  
Vol 8 (2) ◽  
pp. 151-161 ◽  
Author(s):  
Barbora Chattová
Keyword(s):  
Antarctic Peninsula ◽  
Abundant Species ◽  
Weddell Sea ◽  
Diatom Flora ◽  
Fine Grained ◽  
The North ◽  
Large Island ◽  
James Ross Island ◽  
The Antarctic ◽  
North Western

Since 2000, the entire Antarctic diatom flora is being revised using a more fine-grained taxonomy based on a better analysis and interpretation of the morphological and molecular observations. Despite the increased diatom research and efforts, the diversity and ecology of diatoms of lichen inhabiting flora of James Ross Island weren’t studied yet. To reveal the actual diatom diversity, samples were collected during February and March 2018 from lichens on the Ulu Peninsula, James Ross Island, a 2,450 km2 large island, situated in the north-western part of the Weddell Sea, close to the northern tip of the Antarctic Peninsula. The analysis of 29 lichen samples revealed the presence of 56 diatom taxa belonging to 17 genera. The most abundant species were Luticola muticopsis, Hantzschia amphioxys f. muelleri, Pinnularia borealisvar.scalaris, Luticola aff. pusilla and Achnanthes muelleri. Biogeographically, the lichen-inhabiting diatom flora of the Ulu Peninsula is composed of cosmopolitan, Antarctic and endemic elements. The present study is the first focusing on the diversity of lichen-inhabiting diatom communities on James Ross Island, revealing the presence of a rather species rich diatom flora.

scholarly journals Climate change in the western Antarctic Peninsula since 1945: observations and possible causes

1998 ◽  
Vol 27 ◽  
pp. 571-575 ◽  
Author(s):  
J. C. King ◽  
S. A. Harangozo
Keyword(s):  
Sea Ice ◽  
Atmospheric Circulation ◽  
Antarctic Peninsula ◽  
The West ◽  
Sea Ice Extent ◽  
The North ◽  
Ultimate Cause ◽  
Temperature Records ◽  
High Level ◽  
The Antarctic

Temperature records from slations on the west roast of the Antarctic Peninsula show a very high level of interannual variability and, over the last 50 years, larger warming trends than are seen elsewhere in Antarctica. in this paper we investigate the role of atmospheric circulation variability and sea-ice extent variations in driving these changes. Owing to a lack of independent data, the reliability of Antarctic atmospheric analyses produced in the 1950s and 1960s cannot be readily established, but examination of the available data suggests that there has been an increase in the northerly component of the circulation over the Peninsula since the late 1950s. Few observations of sea-ice extent are available prior to 1973, but the limited data available indicate that the ice edge to the west of the Peninsula lay to the north of recently observed extremes during the very cold conditions prevailing in the late 1950s. The ultimate cause of the atmospheric-circulation changes remains to be determined and may lie outside the Antarctic region.

scholarly journals Characteristics of The Seasonal Sea Ice of East Antarctica and Comparisons with Satellite Observations

1987 ◽  
Vol 9 ◽  
pp. 85-91 ◽  
Author(s):  
T.H. Jacka ◽  
I. Allison ◽  
R. Thwaites ◽  
J.C. Wilson
Keyword(s):  
Sea Ice ◽  
Remote Sensing Data ◽  
Ice Cores ◽  
Open Water ◽  
Early Spring ◽  
Visual Channel ◽  
Antarctic Waters ◽  
Study Characteristics ◽  
Satellite Sensors ◽  
The Antarctic

A cruise to Antarctic waters from late October to mid December 1985 provided the opportunity to study characteristics of the seasonal sea ice from a time close to that of maximum extent through early spring decay. The area covered by the observations extends from the northern ice limit to the Antarctic coast between long. 50 °E and 80 E. Shipboard observations included ice extent, type and thickness, and snow depth. Ice cores were drilled at several sites, providing data on salinity and structure.The observations verify the highly dynamic and divergent nature of the Antarctic seasonal sea-ice 2one. Floe size and thickness varied greatly at all locations, although generally increasing from north to south. A high percentage of the total ice mass exhibited a frazil crystal structure, indicative of the existence of open water in the vicinity.The ground based observations are compared with observations from satellite sensors. The remote sensing data include the visual channel imagery from NOAA 6, NOAA 9, and Meteor 11. Comparisons are made with the operational ice charts produced (mainly from satellite data) by the Joint Ice Center, and with the analyses available by facsimile from Molodezhnaya.

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.

Chapter 3.2b Bransfield Strait and James Ross Island: petrology

2021 ◽  
pp. M55-2018-37 ◽  
Author(s):  
Karsten M. Haase ◽  
Christoph Beier
Keyword(s):  
Antarctic Peninsula ◽  
South Shetland Island ◽  
The South ◽  
Bransfield Strait ◽  
Geodynamic Processes ◽  
James Ross Island ◽  
South Shetland Trench ◽  
Low Degrees ◽  
Back Arc ◽  
The Antarctic

AbstractYoung volcanic centres of the Bransfield Strait and James Ross Island occur along back-arc extensional structures parallel to the South Shetland island arc. Back-arc extension was caused by slab rollback at the South Shetland Trench during the past 4 myr. The variability of lava compositions along the Bransfield Strait results from varying degrees of mantle depletion and input of a slab component. The mantle underneath the Bransfield Strait is heterogeneous on a scale of approximately tens of kilometres with portions in the mantle wedge not affected by slab fluids. Lavas from James Ross Island east of the Antarctic Peninsula differ in composition from those of the Bransfield Strait in that they are alkaline without evidence for a component from a subducted slab. Alkaline lavas from the volcanic centres east of the Antarctic Peninsula imply variably low degrees of partial melting in the presence of residual garnet, suggesting variable thinning of the lithosphere by extension. Magmas in the Bransfield Strait form by relatively high degrees of melting in the shallow mantle, whereas the magmas some 150 km further east form by low degrees of melting deeper in the mantle, reflecting the diversity of mantle geodynamic processes related to subduction along the South Shetland Trench.

Spectral linear mixing model applied to data from passive microwave radiometers for sea ice mapping in the Antarctic Peninsula

2021 ◽  
pp. 1-27
Author(s):  
Fernando Luis Hillebrand ◽  
Ulisses Franz Bremer ◽  
Marcos Wellausen Dias de Freitas ◽  
Juliana Costi ◽  
Cláudio Wilson Mendes Júnior ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Mixing Model ◽  
Passive Microwave ◽  
Linear Mixing Model ◽  
Microwave Radiometers ◽  
The Antarctic

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

scholarly journals Surface Albedo of the Antarctic Sea Ice Zone

2005 ◽  
Vol 18 (17) ◽  
pp. 3606-3622 ◽  
Author(s):  
Richard E. Brandt ◽  
Stephen G. Warren ◽  
Anthony P. Worby ◽  
Thomas C. Grenfell
Keyword(s):  
Sea Ice ◽  
Surface Albedo ◽  
Near Infrared ◽  
Field Experiments ◽  
Climate Models ◽  
Solar Spectrum ◽  
Open Water ◽  
Visual Observation ◽  
Antarctic Sea Ice ◽  
The Antarctic

Abstract In three ship-based field experiments, spectral albedos were measured at ultraviolet, visible, and near-infrared wavelengths for open water, grease ice, nilas, young “grey” ice, young grey-white ice, and first-year ice, both with and without snow cover. From the spectral measurements, broadband albedos are computed for clear and cloudy sky, for the total solar spectrum as well as for visible and near-infrared bands used in climate models, and for Advanced Very High Resolution Radiometer (AVHRR) solar channels. The all-wave albedos vary from 0.07 for open water to 0.87 for thick snow-covered ice under cloud. The frequency distribution of ice types and snow coverage in all seasons is available from the project on Antarctic Sea Ice Processes and Climate (ASPeCt). The ASPeCt dataset contains routine hourly visual observations of sea ice from research and supply ships of several nations using a standard protocol. Ten thousand of these observations, separated by a minimum of 6 nautical miles along voyage tracks, are used together with the measured albedos for each ice type to assign an albedo to each visual observation, resulting in “ice-only” albedos as a function of latitude for each of five longitudinal sectors around Antarctica, for each of the four seasons. These ice albedos are combined with 13 yr of ice concentration estimates from satellite passive microwave measurements to obtain the geographical and seasonal variation of average surface albedo. Most of the Antarctic sea ice is snow covered, even in summer, so the main determinant of area-averaged albedo is the fraction of open water within the pack.

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.

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