Sponges of the Lazarev and Weddell Sea, Antarctica: explanations for their patchy occurrence

1995 ◽  
Vol 7 (3) ◽  
pp. 227-234 ◽  
Author(s):  
Julian Gutt ◽  
Vladimir M. Koltun
Keyword(s):  
Continental Shelf ◽  
Weddell Sea ◽  
Small Scale ◽  
Atlantic Sector ◽  
Investigation Area ◽  
Antarctic Continental Shelf ◽  
The Individual ◽  
Environmental Events ◽  
The Antarctic ◽  
First Time

Seventy-three sponge species were caught at 23 stations on the continental shelf of the Lazarev and Weddell Sea (Atlantic sector of the Southern Ocean). Tedania tantula was the most often found species amongst the 63 demosponge species caught and among the five hexactinellid species Rossella racovitzae was most common. The stations were classified according to their species inventory, and so the individual stations of the resulting four groups were rather uniformly dispersed over the entire investigation area. The species composition of adjacent stations varied considerably. There was no discernible relationship between the biological set of data and any combination of the available environmental characteristics of the stations. The sponge fauna of the, so far very poorly investigated, Lazarev Sea did not differ considerably from that of the adjacent Weddell Sea. The only species to be recorded for the first time on the Antarctic continental shelf were Homaxinella flagelliformis and Hyrtios arenosa. Small scale environmental events such as iceberg scouring, or biological characteristics such as extremely slow growth and budding reproduction are thought to generate the patchy distribution pattern.

scholarly journals Explicit and parametrised representation of under ice shelf seas in a z<sup>*</sup> coordinate ocean model

2017 ◽  
Author(s):  
Pierre Mathiot ◽  
Adrian Jenkins ◽  
Christopher Harris ◽  
Gurvan Madec
Keyword(s):  
Sea Ice ◽  
Continental Shelf ◽  
Weddell Sea ◽  
Depth Range ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Antarctic Continental Shelf ◽  
Shelf Seas ◽  
Ocean Properties ◽  
The Antarctic

Abstract. Ice shelf/ocean interactions are a major source of fresh water on the Antarctic continental shelf and have a strong impact on ocean properties, ocean circulation and sea ice. However, climate models based on the ocean/sea ice model NEMO currently do not include these interactions in any detail. The capability of explicitly simulating the circulation beneath ice shelves is introduced in the non-linear free surface model NEMO. Its implementation into the NEMO framework and its assessment in an idealised and realistic circum-Antarctic configuration is described in this study. Compared with the current prescription of ice shelf melting (i.e. at the surface) inclusion of open sub-ice-shelf leads to a decrease sea ice thickness along the coast, a weakening of the ocean stratification on the shelf, a decrease in salinity of HSSW on the Ross and Weddell Sea shelves and an increase in the strength of the gyres that circulate within the over-deepened basins on the West Antarctic continental shelf. Mimicking the under ice shelf seas overturning circulation by introducing the meltwater over the depth range of the ice shelf base, rather than at the surface is also tested. It yields similar improvements in the simulated ocean properties and circulation over the Antarctic continental shelf than the explicit ice shelf cavity representation. With the ice shelf cavities opened, the widely-used “3 equations” ice shelf melting formulation enables an interactive computation of melting that has been assessed. Comparison with observational estimates of ice shelf melting indicates realistic results for most ice shelves. However, melting rates for Amery, Getz and George VI ice shelves are considerably overestimated.

Meiofauna response to iceberg disturbance on the Antarctic continental shelf at Kapp Norvegia (Weddell Sea)

Polar Biology ◽  
2001 ◽  
Vol 24 (12) ◽  
pp. 926-933 ◽  
Author(s):  
Dieter Gerdes ◽  
Sandra Vanhove ◽  
Magda Vincx ◽  
Hee Lee
Keyword(s):  
Continental Shelf ◽  
Weddell Sea ◽  
Antarctic Continental Shelf ◽  
The Antarctic

scholarly journals Explicit representation and parametrised impacts of under ice shelf seas in the <i>z</i><sup>∗</sup> coordinate ocean model NEMO 3.6

2017 ◽  
Vol 10 (7) ◽  
pp. 2849-2874 ◽  
Author(s):  
Pierre Mathiot ◽  
Adrian Jenkins ◽  
Christopher Harris ◽  
Gurvan Madec
Keyword(s):  
Sea Ice ◽  
Continental Shelf ◽  
Weddell Sea ◽  
Surface Model ◽  
Depth Range ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Antarctic Continental Shelf ◽  
Ocean Properties ◽  
The Antarctic

Abstract. Ice-shelf–ocean interactions are a major source of freshwater on the Antarctic continental shelf and have a strong impact on ocean properties, ocean circulation and sea ice. However, climate models based on the ocean–sea ice model NEMO (Nucleus for European Modelling of the Ocean) currently do not include these interactions in any detail. The capability of explicitly simulating the circulation beneath ice shelves is introduced in the non-linear free surface model NEMO. Its implementation into the NEMO framework and its assessment in an idealised and realistic circum-Antarctic configuration is described in this study. Compared with the current prescription of ice shelf melting (i.e. at the surface), inclusion of open sub-ice-shelf cavities leads to a decrease in sea ice thickness along the coast, a weakening of the ocean stratification on the shelf, a decrease in salinity of high-salinity shelf water on the Ross and Weddell sea shelves and an increase in the strength of the gyres that circulate within the over-deepened basins on the West Antarctic continental shelf. Mimicking the overturning circulation under the ice shelves by introducing a prescribed meltwater flux over the depth range of the ice shelf base, rather than at the surface, is also assessed. It yields similar improvements in the simulated ocean properties and circulation over the Antarctic continental shelf to those from the explicit ice shelf cavity representation. With the ice shelf cavities opened, the widely used three equation ice shelf melting formulation, which enables an interactive computation of melting, is tested. Comparison with observational estimates of ice shelf melting indicates realistic results for most ice shelves. However, melting rates for the Amery, Getz and George VI ice shelves are considerably overestimated.

scholarly journals New species and occurrences of <i>Bradleya</i> Benson, 1972, <i>Harleya</i> Jellinek & Swanson, 2003 and <i>Poseidonamicus</i> Benson, 1972 (Ostracoda: Cytheroidea) from the Atlantic Sector of the Southern Ocean

2011 ◽  
Vol 30 (2) ◽  
pp. 141-166 ◽  
Author(s):  
Simone N. Brandão ◽  
Olinga Päplow
Keyword(s):  
New Species ◽  
Southern Ocean ◽  
Geographical Distribution ◽  
Weddell Sea ◽  
Bathymetric Distribution ◽  
Atlantic Sector ◽  
Three New Species ◽  
Abyssal Zone ◽  
The Antarctic ◽  
First Time

Abstract. The Southern Ocean shelf ostracod fauna is quite well known, while the bathyal and abyssal ones remain poorly understood. Herein, Recent Thaerocytheridae ostracods collected from deep regions in the Atlantic Sector of the Southern Ocean are described and figured. The discovery of Bradleya mesembrina Mazzini, 2005 extends its geographical and bathymetric distribution to the Antarctic zone of the Southern Ocean and to shallower (231 m) and to deeper regions (4420 m). Harleya ansoni (Whatley, Moguilevsky, Ramos &amp; Coxill, 1998) is reported for the first time from the Weddell Sea. We also describe three new species: Poseidonamicus hunti Brandão &amp; Päplow sp. nov., Poseidonamicus tainae Brandão sp. nov. and Poseidonamicus yasuharai Brandão &amp; Päplow sp. nov. For the first time we provide SEM photos of the lectotype of Poseidonamicus viminea (Brady, 1880) nomen dubium. We observe that P. yasuharai displays features intermediate to Harleya and Poseidonamicus, indicating that these two genera may require new diagnoses. The bathymetric distribution of Poseidonamicus is extended to the abyssal zone and to shallower environments, and its geographical distribution is extended southwards. Finally, the inter-specific variability in the number and type of setae and claws found on several segments of Poseidonamicus limbs are intermediate between the highly variable Bairdioidea and the homogeneous Macrocyprididae.

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;

Spatial distribution of Antarctic shrimps (Crustacea: Decapoda) by underwater photography

1991 ◽  
Vol 3 (4) ◽  
pp. 363-369 ◽  
Author(s):  
Julian Gutt ◽  
M. Gorny ◽  
W. Arntz
Keyword(s):  
Spatial Distribution ◽  
Continental Shelf ◽  
Weddell Sea ◽  
Small Scale ◽  
Frequency Distributions ◽  
South Eastern ◽  
Direct Observations ◽  
Underwater Photography ◽  
Dispersion Patterns ◽  
Eastern Weddell Sea

Three species of shrimps (Notocrangon antarcticus, Chorismus antarcticus, Nematocarcinus lanceopes) were investigated in the south-eastern Weddell Sea using of underwater photography. Maximum densities of c. 100 specimens per 100 m2 were found for N. antarcticus on the continental shelf (200–600 m) and for N. lanceopes on the slope (800–1200 m). Small-scale dispersion patterns and size-frequency distributions were analyzed within dense concentrations. These direct observations indicate that the behaviour of the three species is adapted to different habitats with Chorismus distribution correlated with that of sponges and Notocrangon with base sediment.

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