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.

Latest Jurassic–earliest Cretaceous age for a fossil flora from the Latady Basin, Antarctic Peninsula

2006 ◽  
Vol 18 (2) ◽  
pp. 261-264 ◽  
Author(s):  
Morag A. Hunter ◽  
David J. Cantrill ◽  
Michael J. Flowerdew
Keyword(s):  
Antarctic Peninsula ◽  
Plant Material ◽  
Weddell Sea ◽  
Detrital Zircons ◽  
Fossil Flora ◽  
Fossil Plant ◽  
The North ◽  
Depositional Age ◽  
The Antarctic ◽  
Basin Margin

Dating Jurassic terrestrial floras in the Antarctic Peninsula has proved problematic and controversial. Here U–Pb series dating on detrital zircons from a conglomerate interbedded with fossil plant material provide a maximal depositional age of 144 ± 3 Ma for a presumed Jurassic flora. This is the first confirmed latest Jurassic-earliest Cretaceous flora from the Latady Basin, and represents some of the youngest sedimentation in this basin. The presence of terrestrial sedimentation at Cantrill Nunataks suggests emergence of the arc closer to the Latady Basin margin in the south compared to Larsen Basin in the north, probably as a result of the failure of the southern Weddell Sea to undergo rifting.

scholarly journals Adult male southern elephant seals from King George Island utilize the Weddell Sea

2008 ◽  
Vol 21 (2) ◽  
pp. 113-121 ◽  
Author(s):  
C.A. Tosh ◽  
H. Bornemann ◽  
S. Ramdohr ◽  
M. Schröder ◽  
T. Martin ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Adult Male ◽  
Weddell Sea ◽  
Adult Males ◽  
King George Island ◽  
Elephant Seals ◽  
The North ◽  
Southern Elephant Seals ◽  
Ice Shelf Water ◽  
The Antarctic

AbstractAdult male southern elephant seals instrumented in 2000 on King George Island (n = 13), travelled both to the north (n = 2) and to the east (n = 6) of the Antarctic Peninsula. Five males remained within 500 km of the island focusing movements in the Bransfield Strait and around the Antarctic Peninsula. Sea surface temperatures encountered by these animals showed little variation. While animal trajectories appeared unaffected by sea ice cover, areas of shallow depths were frequented. Three males moved as far as 75°S to the east of the Peninsula with maximum distances of more than 1500 km from King George Island. They travelled into the Weddell Sea along the western continental shelf break until they reached the region of the Filchner Trough outflow. Here the sea floor consists of canyons and ridges that support intensive mixing between the warm saline waters of the Weddell Gyre, the very cold outflow waters and ice shelf water at the Antarctic Slope Front. The need for re-instrumentation of adult males from King George Island is highlighted to investigate whether males continue to travel to similar areas and to obtain higher resolution data.

scholarly journals Observation of the Emperor penguins Aptenodytes forsteri in the Prince Gustav Channel related with unusual sea-ice decline in north-western Weddell Sea

2019 ◽  
Vol 53 (3) ◽  
pp. 393
Author(s):  
Filip Hrbáček Hrbáček ◽  
Jana Smolíková ◽  
Daniel Nývlt ◽  
Jan Kavan ◽  
Zbyněk Engel
Keyword(s):  
Sea Ice ◽  
Weddell Sea ◽  
Short Paper ◽  
Northern Coast ◽  
The North ◽  
Emperor Penguins ◽  
Observation Area ◽  
Aptenodytes Forsteri ◽  
James Ross Island ◽  
North Western

A pair of juvenile emperor penguins (Aptenodytes forsteri) was observed in the northern coast of James Ross Island, the north-western sector of the Weddell Sea, Antarctica, in January 2017. The penguins originated from the colony located on Snow Hill Island, 120-130 km far from the observation area. Despite the emperor penguin´s ability to migrate over long distances, when they are well-known from different areas in Antarctica, this was the first observation of this species in the north of James Ross Island. In this short paper we discuss the environmental factors which allowed the penguins to reach James Ross Island northern coast, especially significant sea ice variability in this area during last decade.

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.

Table Nunatak: a key outcrop of Upper Cretaceous shallow-marine strata in the southern Larsen Basin, Antarctic Peninsula

1998 ◽  
Vol 135 (4) ◽  
pp. 519-535 ◽  
Author(s):  
B. HATHWAY ◽  
D. I. M. MACDONALD ◽  
J. B. RIDING ◽  
D. J. CANTRILL
Keyword(s):  
Antarctic Peninsula ◽  
Large Scale ◽  
Upper Cretaceous ◽  
Source Area ◽  
Weddell Sea ◽  
Sediment Supply ◽  
Shallow Marine ◽  
Magmatic Arc ◽  
James Ross Island ◽  
The Antarctic

The northern, James Ross Island region of the Larsen Basin, on the eastern, back-arc margin of the Antarctic Peninsula magmatic arc, includes one of the thickest and most complete Upper Cretaceous sedimentary successions exposed in the Southern Hemisphere. However, the southern part of the basin remains poorly known, mainly owing to inaccessibility and lack of exposure. Table Nunatak, an isolated, 1-km-long, 400-m-wide outcrop at the tip of Kenyon Peninsula, is the only known exposure of Upper Cretaceous or younger strata in this region. The 62-m-thick succession exposed there is assigned to the newly defined Table Nunatak Formation. It consists mainly of sharp-based, amalgamated beds of fine-grained sandstone up to 2.8 m thick, with subordinate intervals of intensely bioturbated mudstone. Wave ripples are present at some levels, and locally developed swaley cross-stratification provides evidence for storm-generated combined-flow deposition. However, most sandstone beds appear to be internally structureless apart from normal grading, and are interpreted as the direct suspension deposits of highly sediment-charged storm- and/or flood-related flows. The succession represents relatively nearshore deposition, probably at the mouth of a river or deltaic distributary channel. Charcoalified plant debris, abundant at the tops of some sandstone beds, suggests a periodically wildfire-swept hinterland forested largely by coniferous trees. Dinoflagellate cyst assemblages indicate a late Santonian age, and suggest correlation with the basal part of the Lachman Crags Member of the Santa Marta Formation (Marambio Group) on James Ross Island. Palaeocurrents, sandstone petrography and the high sediment supply rate proposed for the Table Nunatak Formation, suggest a relatively high-relief source area to the west, with large-scale erosion of granitoid plutons and metamorphic rocks, possibly related to arc uplift during a mid-Cretaceous compressional episode. The formation is evidence of a major southward extension of the Upper Cretaceous strata exposed in the northern Larsen Basin, and suggests lateral continuity of shallow-marine deposition for at least 500–600 km along the Weddell Sea margin of the Antarctic Peninsula in Santonian times.

scholarly journals Deep-Water Cartilaginous Fishes in the Central Mediterranean Sea: Comparison between Geographic Areas with Two Low Impact Tools for Sampling

2021 ◽  
Vol 9 (7) ◽  
pp. 686
Author(s):  
Angela Carluccio ◽  
Francesca Capezzuto ◽  
Porzia Maiorano ◽  
Letizia Sion ◽  
Gianfranco D’Onghia
Keyword(s):  
Adriatic Sea ◽  
Fish Habitat ◽  
Conservation Status ◽  
Abundant Species ◽  
Cartilaginous Fish ◽  
Fish Diversity ◽  
Ionian Sea ◽  
Central Mediterranean ◽  
The North ◽  
North Western

Baited lander represents a low impact technique, an alternative to the traditional trawl sampling for collecting data on fish diversity and abundance, especially for threatened species such as Chondrichthyes living in sensitive habitats. In this study, distribution and abundance of cartilaginous fish were compared between two geographic areas, the southern Adriatic Sea and the north-western Ionian Sea, with two low impact sampling gears, an experimental bottom longline and a baited lander. Species diversity was evaluated by applying ecological indices and difference in mean abundances were tested using multivariate analysis. A total of 13 species of cartilaginous fish were collected. Significant differences in the assemblage recorded in the same area using different sampling tools were detected and no significant differences were detected among different areas explored with the same method. Using longline, the most abundant species collected in both areas was Galeus melastomus, while using lander, the most observed species were Dalatias licha in the southern Adriatic Sea and Hexanchus griseus in the north-western Ionian Sea. According to IUCN classification, of the 13 species collected, 2 are near threatened and 5 are threatened. A better governance of sensitive habitats coinciding with the essential fish habitat for these species would ensure them a better conservation status.

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.

Geodynamic implications of the Cenozoic stress field on Seymour Island, West Antarctica

2008 ◽  
Vol 20 (2) ◽  
pp. 173-184 ◽  
Author(s):  
A. Maestro ◽  
J. López-Martínez ◽  
F. Bohoyo ◽  
M. Montes ◽  
F. Nozal ◽  
...  
Keyword(s):  
Stress Field ◽  
Antarctic Peninsula ◽  
Horizontal Stress ◽  
Weddell Sea ◽  
Scotia Sea ◽  
Compressional Stress ◽  
The North ◽  
Stress States ◽  
Bransfield Basin ◽  
Minimum Horizontal Stress

AbstractPalaeostress inferred from brittle mesostructures in Seymour (Marambio) Island indicates a Cenozoic to Recent origin for an extensional stress field, with only local compressional stress states. Minimum horizontal stress (σ3) orientations are scattered about two main NE–SW and NW–SE modes suggesting that two stress sources have been responsible for the dominant minimum horizontal stress directions in the north-western Weddell Sea. Extensional structures within a broad-scale compressional stress field can be linked to both the decrease in relative stress magnitudes from active margins to intraplate regions and the rifting processes that occurred in the northern Weddell Sea. Stress states with NW–SE trending σ3are compatible with back-arc extension along the eastern Antarctic Peninsula. We interpret this as due to the opening of the Larsen Basin during upper Cretaceous to Eocene and to the spreading, from Pliocene to present, of the Bransfield Basin (western Antarctic Peninsula), both due to former Phoenix Plate subduction under the Antarctic Plate. NE–SW σ3orientations could be expressions of continental fragmentation of the northern Antarctic Peninsula controlling eastwards drifting of the South Orkney microcontinent and other submerged continental blocks of the southern Scotia Sea.

scholarly journals Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

2013 ◽  
Vol 7 (3) ◽  
pp. 797-816 ◽  
Author(s):  
T. O. Holt ◽  
N. F. Glasser ◽  
D. J. Quincey ◽  
M. R. Siegfried
Keyword(s):  
Antarctic Peninsula ◽  
Structural Changes ◽  
Surface Elevation ◽  
Ice Shelf ◽  
Ice Shelves ◽  
The North ◽  
Surface Elevation Change ◽  
Elevation Changes ◽  
Negative Surface ◽  
The Antarctic

Abstract. George VI Ice Shelf (GVIIS) is located on the Antarctic Peninsula, a region where several ice shelves have undergone rapid breakup in response to atmospheric and oceanic warming. We use a combination of optical (Landsat), radar (ERS 1/2 SAR) and laser altimetry (GLAS) datasets to examine the response of GVIIS to environmental change and to offer an assessment on its future stability. The spatial and structural changes of GVIIS (ca. 1973 to ca. 2010) are mapped and surface velocities are calculated at different time periods (InSAR and optical feature tracking from 1989 to 2009) to document changes in the ice shelf's flow regime. Surface elevation changes are recorded between 2003 and 2008 using repeat track ICESat acquisitions. We note an increase in fracture extent and distribution at the south ice front, ice-shelf acceleration towards both the north and south ice fronts and spatially varied negative surface elevation change throughout, with greater variations observed towards the central and southern regions of the ice shelf. We propose that whilst GVIIS is in no imminent danger of collapse, it is vulnerable to ongoing atmospheric and oceanic warming and is more susceptible to breakup along its southern margin in ice preconditioned for further retreat.

scholarly journals Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

2013 ◽  
Vol 7 (1) ◽  
pp. 373-417 ◽  
Author(s):  
T. O. Holt ◽  
N. F. Glasser ◽  
D. J. Quincey ◽  
M. R. Siegfried
Keyword(s):  
Antarctic Peninsula ◽  
Structural Changes ◽  
Surface Elevation ◽  
Ice Shelf ◽  
Ice Shelves ◽  
The North ◽  
Surface Elevation Change ◽  
Elevation Changes ◽  
Negative Surface ◽  
The Antarctic

Abstract. George VI Ice Shelf (GVIIS) is located on the Antarctic Peninsula, a region where several ice shelves have undergone rapid breakup in response to atmospheric and oceanic warming. We use a combination of optical (Landsat), radar (ERS 1/2 SAR) and laser altimetry (GLAS) datasets to examine the response of GVIIS to environmental change and to offer an assessment on its future stability. The spatial and structural changes of GVIIS (ca. 1973 to ca. 2010) are mapped and surface velocities are calculated at different time periods (InSAR and optical feature tracking from 1989 to 2009) to document changes in the ice shelf's flow regime. Surface elevation changes are recorded between 2003 and 2008 using repeat track ICESat acquisitions. We note an increase in fracture extent and distribution at the south ice front, ice-shelf acceleration towards both the north and south ice fronts and spatially varied negative surface elevation change throughout, with greater variations observed towards the central and southern regions of the ice shelf. We propose that whilst GVIIS is in no imminent danger of collapse, it is vulnerable to on-going atmospheric and oceanic warming and is more susceptible to breakup along its southern margin in ice preconditioned for further retreat.

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