Additions to knowledge of the biodiversity of benthic hydroids (Cnidaria: Hydrozoa) in the Balleny Islands (Antarctica)

Zootaxa ◽  
2021 ◽  
Vol 4966 (3) ◽  
pp. 321-336
Author(s):  
ÁLVARO L. PEÑA CANTERO
Keyword(s):  
New Zealand ◽  
Continental Shelf ◽  
New Records ◽  
East Antarctica ◽  
Atmospheric Research ◽  
Antarctic Continental Shelf ◽  
Victoria Land ◽  
Small Collection ◽  
The Antarctic

The Balleny Islands, an isolated archipelago located 240 km off the coast of Victoria Land (East Antarctica), are separated from the Antarctic continental shelf by waters more than 2000 m deep. The benthic hydroid fauna of these islands is little known, with only 25 species reported so far. The present study contributes to a better knowledge of the benthic hydrozoans inhabiting this archipelago by studying a small collection held at the National Institute of Water and Atmospheric Research Invertebrate Collection at Wellington, New Zealand. Sixteen species of benthic hydroids were found in the collection, belonging to nine families and 12 genera of Leptothecata. Kirchenpaueriidae and Oswaldella, with three species each, are the most speciose family and genus. Ten species represent new records for the region. The total number of benthic hydroid species known from the islands is raised to 34. 

Pathways and timescales of connectivity around the Antarctic continental shelf 

2021 ◽  
Author(s):  
Hannah Dawson ◽  
Adele Morrison ◽  
Veronica Tamsitt ◽  
Matthew England
Keyword(s):  
Continental Shelf ◽  
Ross Sea ◽  
Coastal Current ◽  
West Antarctica ◽  
Source Regions ◽  
Freshwater Forcing ◽  
Antarctic Continental Shelf ◽  
Antarctic Continent ◽  
Antarctic Slope Current ◽  
The Antarctic

<p><span xml:lang="EN-US" data-contrast="auto"><span>The Antarctic margin is surrounded by two westward flowing currents: the Antarctic Slope Current and the Antarctic Coastal Current. The former influences key processes near the Antarctic margin by regulating the flow of heat and nutrients onto and off the continental shelf, while together they </span></span><span xml:lang="EN-US" data-contrast="auto"><span>advect</span></span><span xml:lang="EN-US" data-contrast="auto"><span> nutrients, biological organisms, and temperature and salinity anomalies around the coastline, providing a connective link between different shelf regions. However, the extent to which these currents transport water from one sector of the continental shelf to another, and the timescales over which this occurs, remain poorly understood. Concern that crucial water formation sites around the Antarctic coastline could respond to non-local freshwater forcing </span></span><span><span xml:lang="EN-US" data-contrast="auto"><span>from ice shel</span></span></span><span><span xml:lang="EN-US" data-contrast="auto"><span>f meltwater</span></span></span> <span xml:lang="EN-US" data-contrast="auto"><span>motivates a more thorough understanding of zonal connectivity around Antarctica. In this study, we use daily velocity fields from a global high-resolution ocean-sea ice model, combined with the <span>Lagrangian</span> tracking software Parcels, to investigate the pathways and timescales connecting different regions of the Antarctic continental shelf<span> with a view to understanding</span><span> the timescales of meltwater transport around the continent</span>. Virtual particles are released over the continental shelf, poleward of the 1000 <span>metre</span> isobath, and are tracked for 20 years. Our results show a strong seasonal cycle connecting different sectors of the Antarctic continent, with more particles arriving further downstream during winter than during summer months. Strong advective links exist between West Antarctica and the Ross Sea while shelf geometry in some other regions acts as barriers to transport. We also highlight the varying importance of the Antarctic Slope Current and Antarctic Coastal Current in connecting different sectors of the coastline. Our results help to improve our understanding of circum-Antarctic connectivity <span>and the timescales </span><span>of meltwater transport from source regions to downstream </span><span>shelf locations. </span><span>Further</span><span>more, t</span><span>he timescales and pathways we </span><span>present </span><span>p</span>rovide a baseline from which to assess long-term changes in Antarctic coastal circulation due to local and remote forcing.<br></span></span></p>

Palaeomagnetic results from the middle Tertiary Meander Intrusives of northern Victoria Land, East Antarctica

1996 ◽  
Vol 8 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Elena Belluso ◽  
Roberto Lanza
Keyword(s):  
Remanent Magnetization ◽  
Ross Sea ◽  
East Antarctica ◽  
Magnetic Mineralogy ◽  
Tilt Correction ◽  
Palaeomagnetic Data ◽  
Victoria Land ◽  
Geological Models ◽  
Laboratory Investigations ◽  
The Antarctic

The Tertiary stocks (Meander Intrusives) cropping out along the coasts of the Ross Sea were sampled for a palaeomagnetic study during the sixth Italian expedition to northern Victoria Land. Laboratory investigations concerned magnetic mineralogy and remanent magnetization. Minerals of the magnetiteulvöspinel series occur in the rocks from all stocks, with low-Ti titanomagnetite usually prevalent. Haematite and goethite occur in small amounts as alteration products. Large secondary components commonly screen the characteristic remanent magnetization and were removed by thermal or AF demagnetization at temperatures or peak-fields higher than 360°C and 20 mT respectively. A total of 10 VGPs were obtained from radiometrically dated rocks (42–22 Ma); the averaged position (69°S, 334°E; α95=9.9°) is the first middle Tertiary palaeomagnetic pole for East Antarctica, and gives evidence for a reversal in the course of the APW path. This evidence is not substantially altered by a supposed tilt-correction consistent with geophysical and geological models for the uplift of the Transantarctic Mountains. No definite conclusion about relative movements between East Antarctica and the Antarctic Peninsula can be drawn from the existing palaeomagnetic data.

Diving behaviour of two Ross seals off east Antarctica

2005 ◽  
Vol 32 (1) ◽  
pp. 63 ◽  
Author(s):  
Colin Southwell
Keyword(s):  
Continental Shelf ◽  
Additional Data ◽  
Prey Species ◽  
Current Knowledge ◽  
East Antarctica ◽  
Maximum Depth ◽  
Diving Behaviour ◽  
Sea Floor ◽  
Transmission Period ◽  
The Antarctic

The Ross seal (Ommatophoca rossii) is the least frequently sighted and least known of the Antarctic pinnipeds. Current knowledge of foraging and diving behaviour is based on observations of a single seal over <2 days. The current study provides some additional data on the diving behaviour of two Ross seals off east Antarctica over periods of 31 and 12 days during December–January 1999–2000 using satellite-linked dive recorders. Both seals remained over the continental shelf for these times, the female remaining some distance from the coast and the male moving close to the coast approximately half-way through his transmission period. Most dives by the female reached depths >150 m (maximum depth 372 m) and the modal duration was 10–11 min. The male’s dives were slightly shallower (most >100 m) and shorter (mode 6–7 min) when distant from the continental coast, and were truncated to a depth of 180 m when close to the coast, presumably by the sea floor. These dive patterns suggest that their prey species, thought to comprise mostly fish and squid, were relatively unavailable at depths <100 m.

scholarly journals Sub-decadal variations in outlet glacier terminus positions in Victoria Land, Oates Land and George V Land, East Antarctica (1972–2013)

2017 ◽  
Vol 29 (5) ◽  
pp. 468-483 ◽  
Author(s):  
A.M. Lovell ◽  
C.R. Stokes ◽  
S.S.R. Jamieson
Keyword(s):  
Antarctic Peninsula ◽  
East Antarctica ◽  
West Antarctica ◽  
Position Change ◽  
Outlet Glacier ◽  
Glacier Terminus ◽  
Victoria Land ◽  
Decadal Scale ◽  
Decadal Variations ◽  
The Antarctic

AbstractRecent work has highlighted the sensitivity of marine-terminating glaciers to decadal-scale changes in the ocean–climate system in parts of East Antarctica. However, compared to Greenland, West Antarctica and the Antarctic Peninsula, little is known about recent glacier change and potential cause(s), with several regions yet to be studied in detail. In this paper, we map the terminus positions of 135 glaciers along the coastline of Victoria Land, Oates Land and George V Land from 1972–2013 at a higher temporal resolution (sub-decadal intervals) than in previous research. These three regions span a range of climatic and oceanic conditions and contain a variety of glacier types. Overall, from 1972–2013, 36% of glaciers advanced, 25% retreated and the remainder showed no discernible change. On sub-decadal timescales, there were no clear trends in glacier terminus position change. However, marine-terminating glaciers experienced larger terminus position changes compared with terrestrial glaciers, and those with an unconstrained floating tongue exhibited the largest variations. We conclude that, unlike in Greenland, West Antarctica and the Antarctic Peninsula, there is no clear glacier retreat in the study area and that most of the variations are more closely linked to glacier size and terminus type.

Geological evidence for changes in the East Antarctica ice sheet (60°–120°E) during the last glaciation

Polar Record ◽  
1991 ◽  
Vol 27 (163) ◽  
pp. 345-355 ◽  
Author(s):  
Eric A. Colhoun
Keyword(s):  
Steady State ◽  
Continental Shelf ◽  
Ice Sheet ◽  
Outer Edge ◽  
East Antarctica ◽  
Geological Evidence ◽  
Marine Transgression ◽  
Last Glaciation ◽  
The Hill ◽  
The Antarctic

AbstractThe East Antarctica ice sheet advanced onto the continental shelf during the last glaciation but appears to have been thinner (<300 m) than previously hypothesised and probably did not everywhere extend to the edge of the continental shelf. Where the shelf is wide, the ice probably terminated against shallow banks on its outer edge. There may not have been time for the sheet to develop the maximum profile form and thickness predicted by Hollin (1962) and Hughes and others (1981) of about 1000–500 moverthe shelf. Large outlet glaciers occupied deep troughs that conveyed most of the ice towards the edge of the shelf: intervening areas were less intensely glaciated. Much of Prince Charles Mountains and Amery Oasis were not ice-covered: Vestfold, Bunger and Casey oases were glaciated. Vestfold and Bunger oases became ice-free after 10 ka BP under the influence of the Holocene marine transgression, which was complete by about 6 ka BP. During at least the last 5–6 ka these oases have been approximately their present size. Since then the margins of the Antarctic continental ice sheet have maintained almost steady state conditions against the landward edges of the hill masses.

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