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.

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.

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. 

The Current Situation in Psychiatry and its Effects on the Delivery of Mental Health Services in the Next Decade

1971 ◽  
Vol 2 (2) ◽  
pp. 138-145 ◽  
Author(s):  
William J. Horvath
Keyword(s):  
Mental Health ◽  
Mental Illness ◽  
Mental Health Services ◽  
Health Services ◽  
Behavioral Treatment ◽  
Additional Data ◽  
Current Knowledge ◽  
Medical Model ◽  
Behavioral Disorder ◽  
Treatment Alternative

As long as mental illness is regarded as primarily a behavioral disorder, current and foreseeable manpower shortages in psychiatry make it necessary to increase the participation of nonmedical personnel in the treatment process. The controversy between those advocating behavioral treatment and those favoring the medical model cannot be resolved due to the fact that our current knowledge of the biologic roots of mental illness is inadequate. A breakthrough in research in this area could resolve the argument and solve the manpower problem by transferring psychiatric disorders into physiologic disease susceptible to medical treatment. Alternative models for the delivery of mental health services can be developed to allow for different possibilities in the outcome of research. Additional data is needed, especially on the costs and effectiveness of future therapies, before an evaluation of programs can be carried out.

scholarly journals Mass balance of the Antarctic ice sheet 1992–2016: reconciling results from GRACE gravimetry with ICESat, ERS1/2 and Envisat altimetry

2021 ◽  
pp. 1-27
Author(s):  
H. Jay Zwally ◽  
John W. Robbins ◽  
Scott B. Luthcke ◽  
Bryant D. Loomis ◽  
Frédérique Rémy
Keyword(s):  
Mass Balance ◽  
Antarctic Peninsula ◽  
East Antarctica ◽  
Mantle Material ◽  
West Antarctica ◽  
Mantle Viscosity ◽  
Grounding Line ◽  
The Antarctic ◽  
Total Gain

Abstract GRACE and ICESat Antarctic mass-balance differences are resolved utilizing their dependencies on corrections for changes in mass and volume of the same underlying mantle material forced by ice-loading changes. Modeled gravimetry corrections are 5.22 times altimetry corrections over East Antarctica (EA) and 4.51 times over West Antarctica (WA), with inferred mantle densities 4.75 and 4.11 g cm−3. Derived sensitivities (Sg, Sa) to bedrock motion enable calculation of motion (δB0) needed to equalize GRACE and ICESat mass changes during 2003–08. For EA, δB0 is −2.2 mm a−1 subsidence with mass matching at 150 Gt a−1, inland WA is −3.5 mm a−1 at 66 Gt a−1, and coastal WA is only −0.35 mm a−1 at −95 Gt a−1. WA subsidence is attributed to low mantle viscosity with faster responses to post-LGM deglaciation and to ice growth during Holocene grounding-line readvance. EA subsidence is attributed to Holocene dynamic thickening. With Antarctic Peninsula loss of −26 Gt a−1, the Antarctic total gain is 95 ± 25 Gt a−1 during 2003–08, compared to 144 ± 61 Gt a−1 from ERS1/2 during 1992–2001. Beginning in 2009, large increases in coastal WA dynamic losses overcame long-term EA and inland WA gains bringing Antarctica close to balance at −12 ± 64 Gt a−1 by 2012–16.

scholarly journals An Assessment of ERA5 Reanalysis for Antarctic Near-Surface Air Temperature

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 217
Author(s):  
Jiangping Zhu ◽  
Aihong Xie ◽  
Xiang Qin ◽  
Yetang Wang ◽  
Bing Xu ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Antarctic Peninsula ◽  
Austral Summer ◽  
Correlation Coefficients ◽  
East Antarctica ◽  
West Antarctica ◽  
Austral Spring ◽  
Reanalysis Dataset ◽  
Near Surface ◽  
The Antarctic

The European Center for Medium-Range Weather Forecasts (ECMWF) released its latest reanalysis dataset named ERA5 in 2017. To assess the performance of ERA5 in Antarctica, we compare the near-surface temperature data from ERA5 and ERA-Interim with the measured data from 41 weather stations. ERA5 has a strong linear relationship with monthly observations, and the statistical significant correlation coefficients (p < 0.05) are higher than 0.95 at all stations selected. The performance of ERA5 shows regional differences, and the correlations are high in West Antarctica and low in East Antarctica. Compared with ERA5, ERA-Interim has a slightly higher linear relationship with observations in the Antarctic Peninsula. ERA5 agrees well with the temperature observations in austral spring, with significant correlation coefficients higher than 0.90 and bias lower than 0.70 °C. The temperature trend from ERA5 is consistent with that from observations, in which a cooling trend dominates East Antarctica and West Antarctica, while a warming trend exists in the Antarctic Peninsula except during austral summer. Generally, ERA5 can effectively represent the temperature changes in Antarctica and its three subregions. Although ERA5 has bias, ERA5 can play an important role as a powerful tool to explore the climate change in Antarctica with sparse in situ observations.

Movements of southern elephant seals

1996 ◽  
Vol 74 (8) ◽  
pp. 1485-1496 ◽  
Author(s):  
B. J. McConnell ◽  
M. A. Fedak
Keyword(s):  
Southern Ocean ◽  
Continental Shelf ◽  
Antarctic Peninsula ◽  
Average Rate ◽  
Stationary Phases ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
South Georgia ◽  
Southern Elephant Seals ◽  
The Antarctic

Twelve southern elephant seals (Mirounga leonina) were tracked for an average of 119 days as they left their breeding or moulting beaches on the island of South Georgia between 1990 and 1994. Females travelled either eastward up to 3000 km away to the open Southern Ocean or to the continental shelf on or near the Antarctic Peninsula. Males either stayed close to South Georgia or used South Georgia as a base for shorter trips. The females all left South Georgia in a directed manner at an average rate of 79.4 km/day over at least the first 15 days. Thereafter travel was interrupted by bouts of slower travel or stationary phases. The latter were localized at sites on the continental shelf or along its edge. Three seals that were tracked over more than one season repeated their outward direction of travel and used some of the same sites in subsequent years. The magnitude of the movements makes most of the Southern Ocean potentially available to elephant seals.

Estimation of turbulent heat fluxes and exchange coefficients for heat at Dumont d'Urville, East Antarctica

1999 ◽  
Vol 11 (1) ◽  
pp. 93-99 ◽  
Author(s):  
S. Argentini ◽  
G. Mastrantonio ◽  
A. Viola
Keyword(s):  
Boundary Layer ◽  
Heat Fluxes ◽  
East Antarctica ◽  
Turbulent Heat ◽  
Convective Boundary ◽  
Doppler Sodar ◽  
Turbulent Heat Fluxes ◽  
Unstable Boundary Layer ◽  
Sodar Measurements ◽  
The Antarctic

Simultaneous acoustic Doppler sodar and tethersonde measurements were used to study some of the characteristics of the unstable boundary layer at Dumont d'Urville, Adélie Land, East Antarctica during the summer 1993–94. A description of the convective boundary layer and its behaviour in connection with the wind regime is given along with the frequency distribution of free convection episodes. The surface heat flux has been evaluated using the vertical velocity variance derived from sodar measurements. The turbulent exchange coefficients, estimated by coupling sodar and tethered balloon measurements, are in strong agreement with those present in literature for the Antarctic regions.

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

&lt;p&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;auto&quot;&gt;&lt;span&gt;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 &lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;auto&quot;&gt;&lt;span&gt;advect&lt;/span&gt;&lt;/span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;auto&quot;&gt;&lt;span&gt; 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 &lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;auto&quot;&gt;&lt;span&gt;from ice shel&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;auto&quot;&gt;&lt;span&gt;f meltwater&lt;/span&gt;&lt;/span&gt;&lt;/span&gt; &lt;span xml:lang=&quot;EN-US&quot; data-contrast=&quot;auto&quot;&gt;&lt;span&gt;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 &lt;span&gt;Lagrangian&lt;/span&gt; tracking software Parcels, to investigate the pathways and timescales connecting different regions of the Antarctic continental shelf&lt;span&gt; with a view to understanding&lt;/span&gt;&lt;span&gt; the timescales of meltwater transport around the continent&lt;/span&gt;. Virtual particles are released over the continental shelf, poleward of the 1000 &lt;span&gt;metre&lt;/span&gt; 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 &lt;span&gt;and the timescales &lt;/span&gt;&lt;span&gt;of meltwater transport from source regions to downstream &lt;/span&gt;&lt;span&gt;shelf locations. &lt;/span&gt;&lt;span&gt;Further&lt;/span&gt;&lt;span&gt;more, t&lt;/span&gt;&lt;span&gt;he timescales and pathways we &lt;/span&gt;&lt;span&gt;present &lt;/span&gt;&lt;span&gt;p&lt;/span&gt;rovide a baseline from which to assess long-term changes in Antarctic coastal circulation due to local and remote forcing.&lt;br&gt;&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;

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