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.

Wave propagation through fields of pack ice

1963 ◽  
Vol 255 (1057) ◽  
pp. 313-339 ◽  
Keyword(s):  
Wave Spectrum ◽  
Experimental Studies ◽  
Normal Wave ◽  
Weddell Sea ◽  
Sea Waves ◽  
Pack Ice ◽  
Order Of Magnitude ◽  
Ice Conditions ◽  
Ice Field ◽  
Ice Floes

Experimental studies of penetration of sea waves and swell into fields of loose pack ice were carried out by means of a ship-borne wave recorder, during a voyage into the Weddell Sea in R.R.S. John Biscoe in 1959—60. This reconnaissance study has provided the first systematic data within an ice field of the variation of wave amplitudes and period over the normal wave spectrum of 4 to 24 s. Although observations were confined to a single ship, a reasonably constant background of swell, together with varied ice conditions, has made it possible to draw certain conclusions for waves and swell of relatively small amplitudes. The penetration of long ocean swell, of periods from 11 to 23 s, into ice fields consisting of large floes of more than half a wavelength across takes place by bending of the floes. The results suggest that the fraction of the wave energy penetrating such an ice field is proportional to A 4/A3, where h is the thickness of the ice floes and A the wavelength of the swell. For periods of less than 10 s, floes of around 1.5 m thick and 40 m or less in diameter approximate to rigid floating plates. For these periods, the main energy cut-off took place when floe diameters were about one-third of the wavelength; little loss of energy occurred when floes were less than one-sixth of the wavelength across, while no detectable penetration took place when the floes were half a wavelength or more in diameter. Consideration of the results, together with limited evidence available from tide and gravimeter observations, shows that most long waves penetrate polar ice fields with little loss of energy. Discussion of the energy required to bend large ice floes indicates that long-period swell is propagated through regions covered by pack ice with little loss of energy only when the energy required to bend the floes is at least an order of magnitude smaller than the total energy of the waves.

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.

Low phytoplankton biomass and ice algal blooms in the Weddell Sea during the ice-filled summer of 1997

2002 ◽  
Vol 14 (3) ◽  
pp. 231-243 ◽  
Author(s):  
ELSE N. HEGSETH ◽  
CECILIE H. VON QUILLFELDT
Keyword(s):  
Algal Blooms ◽  
Phytoplankton Bloom ◽  
Open Water ◽  
Weddell Sea ◽  
Ice Algae ◽  
Ice Shelf ◽  
Growth Season ◽  
Pack Ice ◽  
Phaeocystis Antarctica ◽  
Upper Mixed Layer

The summer of 1997 was characterized by unusually large amounts of pack ice in the southeastern Weddell Sea, and less than 10% of the area that is commonly ice-free in summer was open. A modest phytoplankton bloom developed in the upper mixed layer in the northernmost area (72°S). The bloom peaked in mid-February with max chlorophyll concentrations of 1.5 μg l−1, and integrated stocks of 55–60 mg m−2. Autotrophic flagellates dominated the biomass (80–90% of the chlorophyll) at first, while diatoms increased relative to flagellates during the bloom. Nutrient deficits, however, indicated that a much larger biomass was produced than was observed. Freezing starting after mid-February probably terminated the bloom, resulting in a pelagic growth season limited in time (less than two months) and space. The sea ice had a distinct brown layer of algae, usually at 1–2 m depth, with average chlorophyll biomass of 10.3 mg m−2. The ice cover exhibited a substantial amount of ridges, with ice algae growing in cavities and other structures, but with lower biomass than in the bands. Ice algae were also found growing on the lower 2 m of the ice shelf (visible at low tide). The overall growth season in the ice lasted several months, and ice algal production may have exceeded pelagic production in the Weddell Sea during the growth season of 1997. Pennate diatoms, like Fragilariopsis curta and F. cylindrus, dominated both in ice and in open water above the pycnocline, while Phaeocystis antarctica dominated in deeper layers and in crack pools. Euphausiids, particularly young stages, were frequently observed grazing on ice algae in ridges and on all sides of the floes, (confirmed by the gut content). Ice algae would thus have served as an ample food supply for the krill in the summer of 1997.

Spring distribution, size composition and behaviour of krill Euphausia superba in the western Weddell Sea

Polar Record ◽  
1990 ◽  
Vol 26 (157) ◽  
pp. 85-89 ◽  
Author(s):  
B.I. Bergström ◽  
G. Hempel ◽  
H.-P. Marschall ◽  
A. North ◽  
V. Siegel ◽  
...  
Keyword(s):  
Algal Growth ◽  
Size Composition ◽  
Water Layer ◽  
Open Water ◽  
Euphausia Superba ◽  
Weddell Sea ◽  
Ice Algae ◽  
Remotely Operated Vehicle ◽  
Direct Observations ◽  
Pack Ice

AbstractDistribution, size composition and behaviour of Euphausia superba were investigated in the northwestern Weddell Sea (59–63°S, 45–52°W) in October-November 1988 using RMT trawling, SCUBA diving and visual examination of the ice undersurface using a remotely-operated vehicle (ROV). Amounts of krill washed onto the ice during ice-breaking along transects were noted. Juvenile and sub-adult krill were found, often in high numbers, in association with seasonal pack-ice, from the outer marginal ice zone to at least 200 nautical miles [3 50 km] into the closed pack-ice zone. Krill caught with the RMT or observed within or close to the ice usually had full guts. They were frequently seen feeding on ice algae, and seemed to concentrate in pressure zones, melting ice and infiltration layers, ie where ice provided both confining crevices and rich algal growth. During twilight numbers of krill increased in open water close to the ice, though ROV observations at night revealed even greater numbers remaining in ice cavities. Direct observations from deck, by divers and by ROV, confirmed that most of the krill population in the uppermost water layer was confined to ice habitats, though in three out of 20 RMT catches krill reached densities of 0.1 nr3 ie normal summer values. ‘Miniswarms’ forming in early November may indicate seasonal transition of at least part of the krill population from winter ice habitat and grazing on ice-algae, to summer pelagic life and filter-feeding on phytoplankton.

The Weddell Sea Expedition 2019

2020 ◽  
Author(s):  
John Shears ◽  
Julian Dowdeswell ◽  
Freddie Ligthelm ◽  
Paul Wachter
Keyword(s):  
Sea Ice ◽  
Autonomous Underwater Vehicles ◽  
Remote Sensing Data ◽  
Open Water ◽  
Weddell Sea ◽  
Scientific Programme ◽  
Ice Shelf ◽  
Remotely Operated Vehicle ◽  
Radar Images ◽  
Ice Conditions

<p>The Weddell Sea Expedition 2019 (WSE) was conceived with dual aims: (i) to undertake a comprehensive international inter-disciplinary programme of science centred in the waters around Larsen C Ice Shelf, western Weddell Sea; and (ii) to search for, survey and image the wreck of Sir Ernest Shackleton’s Endurance, which sank in the Weddell Sea in 1915. </p><p>The 6-week long expedition, funded by the Flotilla Foundation, required the use of a substantial ice-strengthened vessel given the very difficult sea-ice conditions encountered in the Weddell Sea, and especially in its central and western parts. The South African ship SA Agulhas II was chartered for its Polar Class 5 icebreaking capability and design as a scientific research vessel. The expedition was equipped with state-of-the-art Autonomous Underwater Vehicles (AUVs) and a Remotely Operated Vehicle (ROV) which were capable of deployment to waters more than 3,000 m deep, thus making the Larsen C continental shelf and slope, and the Endurance wreck site, accessible. During the expedition, a suite of passive and active remote-sensing data, including TerraSAR-X radar images delivered in near real-time, was provided to the ice-pilot onboard the SA Agulhas II. These data were instrumental for safe vessel navigation in sea ice and the detection and tracking of icebergs and ice floes of scientific interest.</p><p>The scientific programme undertaken by the WSE was very successful and produced many new geological, geophysical, marine biological and oceanographic observations from a part of the Weddell Sea that has been little studied previously, particularly the area east of Larsen C Ice Shelf. The expedition also reached the sinking location of Shackleton’s Endurance, where the presence of open-water sea ice leads allowed the deployment of an AUV to the ocean floor to try and locate and survey the wreck. Unfortunately, SA Agulhas II later lost communication with the AUV, and deteriorating weather and sea ice conditions meant that the search had to be called off.</p>

Interaction of Vessel with Channel under Navigation among Small Ice Floes

2015 ◽  
Author(s):  
Vadim K. Goncharov ◽  
Ekaterina S. Zueva ◽  
Natalia Yu. Klementieva
Keyword(s):  
Ice Cover ◽  
Problem Definition ◽  
Arctic Seas ◽  
Cross Sectional ◽  
Side Force ◽  
Pack Ice ◽  
Cross Sectional Dimension ◽  
Ice Conditions ◽  
Fast Ice ◽  
Ice Floes

For maintenance of navigation during wintertime in Arctic seas, icebreakers create the wide channels in the fast ice cover or pack ice cover at water areas near to ports with intensive vessel traffic. Within such wide channels cargo ships and tankers can move in both directions independently without icebreaker pilotage among small ice floes. Because the cross-sectional dimension of the channel is restricted, the ships are forced to displace from the center and move on a close distance between their board and border of channel. The space between ship hull and borders is filled by small ice floes, and its concentration near the starboard and portside differs. The ice resistance on each board also differs. Therefore, side force and yawing moment arise that are able to cause the collision with the channel border. This paper contains the detailed problem definition and the main points of the mathematical model of vessel interaction with the channel border. As an example of model application possibilities, the simulation of loads on the hull of the vessel was performed. Outcomes of the investigation are dependent upon the side force and yawing moment on the distance from the channel border and ice conditions.

Aggregation of mummified adult crabeater seals (Pinnipedia: Phocidae) in the eastern Antarctic Peninsula: age and sex structure, taphonomy and cause of death

2014 ◽  
Vol 27 (3) ◽  
pp. 274-280 ◽  
Author(s):  
Javier Negrete ◽  
Leopoldo h. Soibelzon ◽  
Esteban Soibelzon ◽  
María E.I. Márquez ◽  
Cleopatra M. Loza ◽  
...  
Keyword(s):  
Stomach Content ◽  
Age And Gender ◽  
Sex Structure ◽  
Mass Mortality Event ◽  
Content Analyses ◽  
Crabeater Seals ◽  
And Gender ◽  
Natural Trap ◽  
Seymour Island ◽  
Age And Sex

AbstractIn Antarctica, crabeater seals tend to strand as immature animals with disorientation, due to their inexperience, given as the probable cause. In 2012 and 2013, we examined a group of 80 mummified crabeater seals on Seymour Island (Marambio). The age and gender of 28 seals was determined, and virology and stomach content analyses were performed in order to determine the cause of stranding. Around 82% of the seals examined were adults and 79% were females, some of which were pregnant. All of the seals sampled tested negative for Morbillivirus, suggesting that the stranding was not related to the mass mortality event reported in the 1950s in the region. Most seals had empty stomachs and thin blubber suggesting that they died from starvation. The state of the carcasses suggests multiple stranding events. Most of the seals were located along an ice-covered stream, suggesting that this may act as a ‘natural trap’, isolating the seals from the open ocean. This is exceptional as it is the first report of mostly adult female seals to strand in Antarctica and refutes the theory that only young animals are prone to stranding.

Discrete Element Modelling of Pack Ice Interaction With Floating Structures

2015 ◽  
Author(s):  
Jie Dai ◽  
Heather Peng
Keyword(s):  
Discrete Element ◽  
Wave Force ◽  
Interaction Force ◽  
Discrete Element Modelling ◽  
Empirical Formulas ◽  
Pack Ice ◽  
Broken Ice ◽  
Ice Conditions ◽  
Ice Field ◽  
Ice Floes

This paper presents a two-dimensional numerical model for ship-ice interaction simulatiion using the discrete element method (DEM). The simulation was conducted for a broken ice field with hundreds of circular ice floes and various combinations of ice conditions. A viscous-elastic ice rheology was adopted to model the dynamic behavior of each individual ice floe. Both ship-ice and ice-ice contacts were considered in the interaction force. Environment forces, including wind force and wave force, were calculated by empirical formulas. An algorithm was developed to log each contact and solve motions of individual ice floe and the ship. The resistance of ship advancing in ice was predicted and compared with model test results.

scholarly journals The Polar Bear and its Protection

Oryx ◽  
1956 ◽  
Vol 3 (5) ◽  
pp. 233-239 ◽  
Author(s):  
Alan G. Loughrey
Keyword(s):  
Sea Ice ◽  
Polar Bear ◽  
East Coast ◽  
Open Water ◽  
Large Degree ◽  
Hudson Bay ◽  
Large Size ◽  
Pack Ice ◽  
Time Of Year ◽  
Ice Floes

The polar bear, Thalarctos maritimus, (Phipps) enjoys such colloquial names as: “ice-bear,” “sea-bear,” “ice-tiger” and “ice-king.” In view of its large size and its supremacy over the other beasts of the ice-floes it well deserves these epithets. Primarily the polar bear is an animal of the broken arctic pack ice and is found in greatest numbers along the southern edge of the pack. It avoids large expanses of open water or frozen sea ice. The movements of the pack ice to a large degree determine its distribution and movements. Polar bears are carried southward with the pack ice in the spring and summer. In August and September when the ice begins to break up they generally come ashore and make their way north. At this time of year they may be found in considerable numbers along certain coasts where the sea ice has been brought by the winds, tides and currents. An Eskimo from Southampton Island, in northern Hudson Bay, informed me that in August, 1948, he and a companion counted over 180 of these bears along the east coast of that island.

Hull Forms for Icebreaking Tankers

2004 ◽  
Author(s):  
Hyun-Soo Kim ◽  
Mun-Keun Ha ◽  
Dang Ahn ◽  
David Molyneux ◽  
Ho Hwan Chun
Keyword(s):  
Open Water ◽  
Ship Design ◽  
Pack Ice ◽  
Ice Conditions ◽  
Level Ice ◽  
Arctic Ice ◽  
Trade Route ◽  
Open Water Performance ◽  
Hull Forms ◽  
Almost All

The optimum design for an icebreaking tanker will depend on the trade route and the cargo delivery requirements. For example, the hull shape of a ship that spends almost all of its time operating in heavy ice can be optimized for low speed icebreaking conditions. In contrast, a ship that spends a small portion of its time in light ice that has been previously broken and the rest of its time in open water can be optimized for different requirements. The challenge for the designer is complicated by the observation that many ship design features that enhance powering performance in ice are detrimental to open water performance. This paper presents predictions of ship resistance in pack ice, level ice and open water for four tanker designs, which include a conventional hull with no modification for ice at all and three designs proposed for operation in Arctic ice conditions. The predictions of ship performance are based on model experiments carried out in Canada and Korea. The resistance of the four hulls in open water, two concentrations of pack ice and two level ice thicknesses are compared and discussed. Information of this sort is essential for developing the optimum ship design for a particular shipping route, given known profiles of open water, pack ice and level ice.

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