Surface Circulation at the Tip of the Antarctic Peninsula from Drifters

Abstract An array of 40 surface drifters, drogued at 15-m depth, was deployed in February 2007 to the east of the tip of the Antarctic Peninsula as part of the Antarctic Drifter Experiment: Links to Isobaths and Ecosystems (ADELIE) project. Data obtained from these drifters and from a select number of local historical drifters provide the most detailed observations to date of the surface circulation in the northwestern Weddell Sea. The Antarctic Slope Front (ASF), characterized by a ∼20 cm s−1 current following the 1000-m isobath, is the dominant feature east of the peninsula. The slope front bifurcates when it encounters the South Scotia Ridge with the drifters following one of three paths. Drifters (i) are carried westward into Bransfield Strait; (ii) follow the 1000-m isobath to the east along the southern edge of the South Scotia Ridge; or (iii) become entrained in a large-standing eddy over the South Scotia Ridge. Drifters are strongly steered by contours of f /h (Coriolis frequency/depth) as shown by calculations of the first two moments of displacement in both geographic coordinates and coordinates locally aligned with contours of f /h. An eddy-mean decomposition of the drifter velocities indicates that shear in the mean flow makes the dominant contribution to dispersion in the along-f /h direction, but eddy processes are more important in dispersing particles across contours of f /h. The results of the ADELIE study suggest that the circulation near the tip of the Antarctic Peninsula may influence ecosystem dynamics in the Southern Ocean through Antarctic krill transport and the export of nutrients.

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A Discussion on volcanism and the structure of the Earth - The evolution of the Scotia Ridge and Scotia Sea

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1972.0005 ◽

1972 ◽

Vol 271 (1213) ◽

pp. 151-183 ◽

Cited By ~ 72

Keyword(s):

South America ◽

Antarctic Peninsula ◽

Weddell Sea ◽

East Antarctica ◽

The South ◽

Scotia Sea ◽

South Georgia ◽

Scotia Ridge ◽

Magnetic Lineations ◽

The Antarctic

Marine geophysical surveys over the Scotia Ridge show it to be composed of blocks mainly of continental origin. Major structures found on the blocks are in many cases truncated at block margins and their existence is also inconsistent with the present isolated situation of the blocks. The evidence suggests post-Upper Cretaceous fragmentation of a continuous continental area. Complementary marine geomagnetic studies over the deep water of the Scotia Sea have dated two areas as younger than 22 million years (Ma) and have indicated the direction of spreading in others. A model of present plate motions, based on the magnetic anomalies, explains the active volcanism of the South Sandwich Islands as being caused by consumption of Atlantic crust at the associated trench at a rate of 5.5 cm/year for the past 7 to 8 Ma at least. An Upper Tertiary episode of plate consumption at 5 cm/year at the South Shetland trench, suggested by the magnetic lineations, with a secondary slow extensional widening of Bransfield Strait is used to explain similarly the contemporaneous volcanism of the South Shetland Is. Making the reasonable assumption of a Tertiary formation of the undated parts of the Scotia Sea by spreading in the directions indicated by the magnetic lineations, a tentative reconstruction of the component blocks of the Scotia Ridge is made. The attempt is only partly successful in matching structural patterns across adjacent margins of reconstructed blocks, South Georgia being most obviously wrongly situated. It is suggested that the misfits result from minor errors in the initial assumptions and the modification of structures during fragmentation and drift. South Georgia may have formed on the Atlantic rather than the Pacific side of the compact continental region which is thought to have joined South America and west Antarctica for much of the Mesozoic at least. A Gondwanaland reconstruction is presented which is consistent with the Scotia Ridge reconstruction, in which the Antarctic Peninsula lies alongside the Caird Coast of east Antarctica. Upon break-up of Gondwanaland, the Antarctic Peninsula remained rigidly attached to South America, east Antarctica rotating clockwise to open the Weddell Sea, until early Tertiary times when the Peninsula transferred to east Antarctica which continued rotating clockwise to open the Scotia Sea.

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Metagenomic characterization of the viral community of the South Scotia Ridge

10.1101/451732 ◽

2018 ◽

Author(s):

Qingwei Yang ◽

Chen Gao ◽

Yong Jiang ◽

Min Wang ◽

Xinhao Zhou ◽

...

Keyword(s):

Pacific Ocean ◽

Antarctic Peninsula ◽

Phylogenetic Analyses ◽

Marker Genes ◽

Scotia Ridge ◽

The Pacific ◽

Viral Communities ◽

The Pacific Ocean ◽

The Antarctic ◽

South Scotia Ridge

AbstractViruses are the most abundant biological entities in aquatic ecosystems and harbor an enormous genetic diversity. While their great influence on the marine ecosystems is widely acknowledged, current information about their diversity remains scarce. Aviral metagenomic analysis of two surfaces and one bottom water sample was conducted from sites on the South Scotia Ridge (SSR) near the Antarctic Peninsula, during the austral summer 2016. The taxonomic composition and diversity of the viral communities were investigated and a functional assessment of the sequences was determined. Phylotypic analysis showed that most viruses belonging to the order Caudovirales, in particular, the family Podoviridae (41.92-48.7%), which is similar to the viral communities from the Pacific Ocean. Functional analysis revealed a relatively high frequency of phage-associated and metabolism genes. Phylogenetic analyses of phage TerL and Capsid_NCLDV (nucleocytoplasmic large DNA viruses) marker genes indicated that many of the sequences associated with Caudovirales and NCLDV were novel and distinct from known complete phage genomes. High Phaeocystis globosa virus virophage (Pgvv) signatures were found in SSR area and complete and partial Pgvv-like were obtained which may have an influence on host-virus interactions in the area during summer. Our study expands the existing knowledge of viral communities and their diversities from the Antarctic region and provides basic data for further exploring polar microbiomes.ImportanceIn this study, we used high-throughput sequencing and bioinformatics analysis to analyze the viral community structure and biodiversity of SSR in the open sea near the Antarctic Peninsula. The results showed that the SSR viromes are novel, oceanic-related viromes and a high proportion of sequence reads was classified as unknown. Among known virus counterparts, members of the order Caudovirales were most abundant which is consistent with viromes from the Pacific Ocean. In addition, phylogenetic analyses based on the viral marker genes (TerL and MCP) illustrate the high diversity among Caudovirales and NCLDV. Combining deep sequencing and a random subsampling assembly approach, a new Pgvv-like group was also found in this region, which may a signification factor regulating virus-host interactions.

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Metagenomic Characterization of the Viral Community of the South Scotia Ridge

10.20944/preprints201810.0666.v1 ◽

2018 ◽

Author(s):

Qingwei Yang ◽

Chen Gao ◽

Jiang Yong ◽

Ming Wang ◽

Xinhao Zhou ◽

...

Keyword(s):

Phylogenetic Analyses ◽

Great Influence ◽

Austral Summer ◽

Taxonomic Composition ◽

Marker Genes ◽

The South ◽

Scotia Ridge ◽

Viral Communities ◽

The Antarctic ◽

South Scotia Ridge

Viruses are the most abundant biological entities in aquatic ecosystems and harbor an enormous genetic diversity. While their great influence on the marine ecosystems is widely acknowledged, current information about their diversity remains scarce. A viral metagenomic analysis of three water samples was conducted from sites on the South Scotia Ridge (SSR) near the Antarctic Peninsula, during the austral summer 2016. The taxonomic composition and diversity of the viral communities were investigated and a functional assessment of the sequences was determined. Phylotypic analysis showed that most viruses belonging to the order Caudovirales, especially the family Podoviridae (41.92-48.7%), similar to the viromes from the Pacific Ocean. Functional analysis revealed a relatively high frequency of phage-associated and metabolism genes. Phylogenetic analyses of phage TerL and Capsid_NCLDV (nucleocytoplasmic large DNA viruses) marker genes indicated that many sequences associated with Caudovirales and NCLDV were novel and distinct from known phage genomes. High Phaeocystis globosa virus virophage (Pgvv) signatures were found in SSR area and complete and partial Pgvv-like were obtained which may have an influence on host-virus interactions. Our study expands the existing knowledge of viral communities and their diversities from the Antarctic region and provides basic data for further exploring polar microbiomes.

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Natural iron enrichment around the Antarctic Peninsula in the Southern Ocean

Biogeosciences Discussions ◽

10.5194/bgd-6-7481-2009 ◽

2009 ◽

Vol 6 (4) ◽

pp. 7481-7515 ◽

Cited By ~ 6

Author(s):

M. V. Ardelan ◽

O. Holm-Hansen ◽

C. D. Hewes ◽

C. S. Reiss ◽

N. S. Silva ◽

...

Keyword(s):

Antarctic Peninsula ◽

Weddell Sea ◽

South Shetland Islands ◽

The South ◽

Total Acid ◽

Shetland Islands ◽

Iron Enrichment ◽

Bransfield Strait ◽

Natural Iron ◽

The Antarctic

Abstract. As part of the US-AMLR program that occupied 99 hydrographic stations in the South Shetland Islands-Antarctic Peninsula region in January–February of 2006, concentrations of dissolved iron (DFe) and total acid-leachable iron (TaLFe) were measured in the upper 150 m at 16 stations (both coastal and pelagic waters). The concentrations in the upper mixed layer (UML) of DFe and TaLFe were relatively high in Weddell Sea Shelf Waters (~0.6 nM and 15 nM, respectively) and lowest in Drake Passage waters (~0.2 nM and 0.9 nM, respectively). In the Bransfield Strait, representing a mixture of waters from the Weddell Sea and the Antarctic Circumpolar Current (ACC), concentrations of DFe were ~0.4 nM and of TaLFe ~1.7 nM. The highest concentrations of DFe and TaLFe in the UML were found at shallow coastal stations close to Livingston Island (~1.6 nM and 100 nM, respectively). The ratio of TaLFe:DFe varied with the distance to land: ~45 at the shallow coastal stations, ~15 in the high-salinity waters of Bransfield Strait, and ~4 in ACC waters. Concentrations of DFe increased slightly with depth in the water column, while that of TaLFe did not show any consistent trend with depth. Our data are consistent with the hypothesis that the relatively high rates of primary production known from the central regions of the Scotia Sea are partially sustained by natural iron enrichment resulting from a northeasterly flow of iron-rich coastal waters originating in the South Shetland Islands-Antarctic Peninsula region.

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Spatial Structure and Intra-Annual Variability of Weddell Sea Front based on the Data of NOAA OISST Reanalysis

Ekologicheskaya bezopasnost pribrezhnoy i shel fovoy zon morya ◽

10.22449/2413-5577-2020-4-89-102 ◽

2020 ◽

Author(s):

Yu. V. Artamonov ◽

E. A. Skripaleva ◽

N. V. Nikolsky ◽

◽

...

Keyword(s):

Spatial Structure ◽

Antarctic Peninsula ◽

Time Lag ◽

Water Area ◽

Weddell Sea ◽

The South ◽

Orkney Islands ◽

Bransfield Strait ◽

South Orkney Islands ◽

The Antarctic

Based on the NOAA OISST reanalysis data, the spatial structure of the Weddell Sea Front in the climatic field of the sea surface temperature was analyzed and the seasonal variability of front’s characteristics was estimated. The spatial position of the frontal zone in the Weddell Sea was analyzed using distributions of the total horizontal temperature gradient. The characteristics of the front (the position of the gradients' extrema corresponding to the front, their magnitude and temperature on the front axis) were determined for each month on the profiles of meridional and zonal temperature gradients along meridians and parallels with a discreteness of 2.5° of longitude and 0.25° of latitude. It is shown that the interaction of Weddell Sea cold waters, which are transported by currents northward along the Antarctic Peninsula coasts, with the warmer waters of the eastern shelf of the Antarctic Peninsula and the Bransfield Strait surface water causes formation of two branches of the Weddell Sea Front. These branches round from a vast shelf at the Antarctic Peninsula tip and the Joinville archipelago the south and north and are traced further east along the boundaries of the bottom rise located approximately between 62.5S and 64.5S. To the south of the South Orkney Islands shelf, the two branches merge into one front, which follows to the east along the depth dump of the relative shallow between the South Orkney and South Sandwich Islands. In the seasonal cycle of the Weddell Sea Front intensity, a time lag was revealed of the front intensification period in the direction from west to east. In Bransfield Strait the front is most intense in February, between the Antarctic Peninsula tip and the South Orkney Islands – in March, east of the South Orkney Islands – in April. The branch of the Weddell Sea Front off the northeastern of the Antarctic Peninsula coasts intensifies in November – January, in the western part of the water area east of the James Ross and Snow Hill Islands – in January – February.

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Continental fragmentation along the South Scotia Ridge transcurrent plate boundary (NE Antarctic Peninsula)

Tectonophysics ◽

10.1016/0040-1951(95)00211-1 ◽

1996 ◽

Vol 258 (1-4) ◽

pp. 275-301 ◽

Cited By ~ 65

Author(s):

J. Galindo-Zaldívar ◽

A. Jabaloy ◽

A. Maldonado ◽

C. Sanz de Galdeano

Keyword(s):

Antarctic Peninsula ◽

Plate Boundary ◽

The South ◽

Scotia Ridge ◽

South Scotia Ridge

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Metagenomic Characterization of the Viral Community of the South Scotia Ridge

Viruses ◽

10.3390/v11020095 ◽

2019 ◽

Vol 11 (2) ◽

pp. 95 ◽

Cited By ~ 6

Author(s):

Qingwei Yang ◽

Chen Gao ◽

Yong Jiang ◽

Min Wang ◽

Xinhao Zhou ◽

...

Keyword(s):

Phylogenetic Analyses ◽

Austral Summer ◽

Taxonomic Composition ◽

Marker Genes ◽

The South ◽

Scotia Ridge ◽

Viral Communities ◽

Nucleocytoplasmic Large Dna Viruses ◽

The Antarctic ◽

South Scotia Ridge

Viruses are the most abundant biological entities in aquatic ecosystems and harbor an enormous amount of genetic diversity. Whereas their influence on marine ecosystems is widely acknowledged, current information about their diversity remains limited. We conducted a viral metagenomic analysis of water samples collected during the austral summer of 2016 from the South Scotia Ridge (SSR), near the Antarctic Peninsula. The taxonomic composition and diversity of the viral communities were investigated, and a functional assessment of the sequences was performed. Phylotypic analysis showed that most viruses belonged to the order Caudovirales, especially the family Podoviridae (41.92–48.7%), which is similar to the situation in the Pacific Ocean. Functional analysis revealed a relatively high frequency of phage-associated and metabolism genes. Phylogenetic analyses of phage TerL and Capsid_NCLDV (nucleocytoplasmic large DNA viruses) marker genes indicated that many sequences associated with Caudovirales and NCLDV were novel and distinct from known phage genomes. High Phaeocystis globosa virus virophage (Pgvv) signatures were found and complete and partial Pgvv-like were obtained, which influence host–virus interactions. Our study expands existing knowledge of viral communities and their diversities from the Antarctic region and provides basic data for further exploring polar microbiomes.

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Seismicity and tectonics around the northern Antarctic Peninsula from King Sejong station data

Antarctic Science ◽

10.1017/s0954102000000250 ◽

2000 ◽

Vol 12 (2) ◽

pp. 196-204 ◽

Cited By ~ 3

Author(s):

D.K. Lee ◽

Y.K. Jin ◽

Y. Kim ◽

S.H. Nam

Keyword(s):

Antarctic Peninsula ◽

Fracture Zone ◽

Normal Fault ◽

The South ◽

Seismicity And Tectonics ◽

South Shetland Trench ◽

Bransfield Basin ◽

Shackleton Fracture Zone ◽

The Antarctic ◽

South Scotia Ridge

Local earthquakes recorded at the King Sejong station (62° 13′31″S, 58° 47′07″W) from 1995–96 have been analysed to study the seismicity and tectonics around the northern Antarctic Peninsula. The nature of shallow-focused normal fault earthquakes along the South Shetland Platform is still unclear. Dominant normal fault earthquakes and minor strike-slip earthquakes in the Eastern Bransfield Basin suggest 1) ongoing extension, and 2) transtensional stress transmitted from the Antarctic–Scotia transform boundaries, the South Scotia Ridge and the Shackleton Fracture Zone. A lack of seismicity in the Central Bransfield Basin supports that active seismicity in the Eastern Bransfield Basin is not a result of subduction along the South Shetland Trench. Shallow focused earthquakes have been observed along the NW–SE trending gravity low line between the Central and the Eastern Bransfield Basins that approximately coincides with the landward projection of a fracture zone in the former Phoenix Plate.

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