scholarly journals Glacimarine sediment flows in small bays on the Danco Coast, Antarctic Peninsula

2021 ◽  
Vol 50 (SuplEsp) ◽  
pp. 149-168
Author(s):  
Cristian Rodrigo ◽  
Andrés Varas ◽  
César Grisales ◽  
Diana Quintana ◽  
Ricardo Molares
Keyword(s):  
Antarctic Peninsula ◽  
Central Area ◽  
Average Particle ◽  
Western Antarctic Peninsula ◽  
Glacier Melting ◽  
Tidewater Glacier ◽  
Glacier Front ◽  
Glacial Melting ◽  
Glaciomarine Sediments ◽  
The Antarctic

Global atmospheric warming and rising ocean temperatures can contribute to the acceleration of glacier melting and influence the generation and physical characteristics of sediment flows in bays and fjords of the Antarctic Peninsula. During the First Scientific Expedition of Colombia to the Antarctic, carried out between January and February 2015, hydrographic variables (temperature, salinity, pressure and turbidity) were measured in the water column, from very close to the main glacier front towards the offshore, on 5 bays of the Danco Coast, Western Antarctic Peninsula. Glacimarine sediment plumes from the tidewater glacier were identified in all bays, however, with varying spatial extensions as well as the concentration of sediments, being those of the central area of the Danco Coast, the most extensive and concentrated. By comparison with previous years, in this work higher average particle concentrations were recorded. The greater flow of glaciomarine sediments could be associated with greater glacial melting, among other possible factors

scholarly journals Variations of glacier frontal positions on the northern Antarctic Peninsula

2004 ◽  
Vol 39 ◽  
pp. 525-530 ◽  
Author(s):  
Frank Rau ◽  
Fabian Mauz ◽  
Hernán De Angelis ◽  
Ricardo Jaña ◽  
Jorge Arigony Neto ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Thermal Emission ◽  
General Trend ◽  
Glacier Recession ◽  
Research Initiative ◽  
Glacier Front ◽  
James Ross Island ◽  
Investigation Period ◽  
The Antarctic ◽  
Local Accumulation

AbstractChanges in the ice fronts on the Antarctic Peninsula north of 70˚ S are currently being investigated through a comprehensive analysis of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Landsat Thematic Mapper (TM) data as part of the international research initiative ‘Global land Ice Measurements from Space’ (GLIMS). Regional case studies are presented that cover a variety of glacial systems distributed over the northern Antarctic Peninsula and provide data on glacier front variations during the period 1986–2002. The results confirm a general trend of regional glacier front recession, but a range of different glacier variations are observed throughout the study area. Areas of predominant retreat are located in the northeastern and southwestern sectors, while stationary ice fronts characterize glacial behaviour on the northwestern coast of the peninsula. In addition, a significant increase in glacier recession is identified on James Ross Island, where retreat rates doubled during the period 1988–2001 compared to the previous investigation period, 1975–88. These observations are interpreted as being direct consequences of the rapidly changing climate in the region, which differentially affects the local accumulation and ablation patterns of the glacial systems.

Late Miocene Asterozoans (Echinodermata) in the James Ross Island Volcanic Group

2006 ◽  
Vol 18 (1) ◽  
pp. 117-122 ◽  
Author(s):  
Mark Williams ◽  
John L. Smellie ◽  
Joanne S. Johnson ◽  
Daniel B. Blake
Keyword(s):  
Antarctic Peninsula ◽  
Late Miocene ◽  
Volcanic Group ◽  
Antarctic Marine ◽  
Morphological Detail ◽  
James Ross Island ◽  
Ecology And Environment ◽  
Fossil Data ◽  
Glaciomarine Sediments ◽  
The Antarctic

Asterozoans (Echinodermata) of Late Miocene age (6.02 ± 0.12 Ma) are preserved as external moulds in water-lain tuffs of the James Ross Island Volcanic Group (JRIVG), James Ross Island, Antarctic Peninsula. The asterozoans are complete, and appear to represent specimens suffocated after having been pinioned by rapid sedimentation on the distal fringe of an erupting sub-aqueous tuff cone. Although the coarse nature of the host sediments has obliterated the fine morphological detail of the specimens, at least one suggests evidence of entrainment by a turbidity current. A second shows evidence of detachment of the distal tip of one of its arms. In addition to fossil discoveries from glaciomarine sediments, the volcanic tuffs of the JRIVG represent a new source of fossil data that can be used to interpret the ecology and environment of the Antarctic marine shelf biota during the Neogene.

scholarly journals Every Rule Has an Exception: a Cheater in the Community-Wide Mutualism in Antarctic Seaweed Forests

2020 ◽  
Vol 60 (6) ◽  
pp. 1358-1368
Author(s):  
Sabrina Heiser ◽  
Charles D Amsler ◽  
James B McClintock ◽  
Andrew J Shilling ◽  
Bill J Baker
Keyword(s):  
Primary Production ◽  
Antarctic Peninsula ◽  
Ecosystem Engineers ◽  
Chemical Defenses ◽  
Western Antarctic Peninsula ◽  
Macroalgal Species ◽  
Antarctic Ecosystem ◽  
Ecological Roles ◽  
The Antarctic ◽  
Plocamium Cartilagineum

Synopsis Dense macroalgal forests on the Western Antarctic Peninsula serve important ecological roles both in terms of considerable biomass for primary production as well as in being ecosystem engineers. Their function within the Antarctic ecosystem has been described as a crucial member of a community-wide mutualism which benefits macroalgal species and dense assemblages of associated amphipod grazers. However, there is a cheater within the system that can feed on one of the most highly chemically defended macroalgal hosts. The amphipod Paradexamine fissicauda has been found to readily consume the finely branched red macroalga Plocamium cartilagineum. This amphipod grazer not only feeds on its host, but also appears to sequester its host’s chemical defenses for its own utilization. This review summarizes what we know about both of these exceptions to the community-wide mutualism.

scholarly journals From ice-shelf tributary to tidewater glacier: continued rapid recession, acceleration and thinning of Röhss Glacier following the 1995 collapse of the Prince Gustav Ice Shelf, Antarctic Peninsula

2011 ◽  
Vol 57 (203) ◽  
pp. 397-406 ◽  
Author(s):  
N.F. Glasser ◽  
T.A. Scambos ◽  
J. Bohlander ◽  
M. Truffer ◽  
E. Pettit ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Satellite Image ◽  
Ice Shelf ◽  
Tidewater Glaciers ◽  
Speed Increase ◽  
Glacier System ◽  
Digital Elevation ◽  
Tidewater Glacier ◽  
Before And After ◽  
The Antarctic

AbstractWe use optical (ASTER and Landsat) and radar (ERS-1 and ERS-2) satellite imagery to document changes in the Prince Gustav Ice Shelf, Antarctic Peninsula, and its tributary glaciers before and after its January 1995 collapse. The satellite image record captures the transition from an ice-shelf glacier system to a tidewater glacial system and the subsequent rapid retreat and inferred ‘fatal’ negative mass balances that occur as lower glacier elevations lead to higher ablation and tidewater-style calving collapse. Pre-1995 images show that the central ice shelf was fed primarily by Sjögren Glacier flowing from the Antarctic Peninsula and by Röhss Glacier flowing from James Ross Island. Numerous structural discontinuities (rifts and crevasses) and melt ponds were present on the ice shelf before the collapse. After the ice shelf collapsed, Röhss Glacier retreated rapidly, becoming a tidewater glacier in 2002 and receding a total of ∼15 km between January 2001 and March 2009, losing >70% of its area. Topographic profiles of Röhss Glacier from ASTER-derived digital elevation models show a thinning of up to ∼150 m, and surface speeds increased up to ninefold (0.1–0.9 m d−1) over the same period. The rates of speed increase and elevation loss, however, are not monotonic; both rates slowed between late 2002 and 2005, accelerated in 2006 and slowed again in 2008–09. We conclude that tributary glaciers react to ice-shelf removal by rapid (if discontinuous) recession, and that the response of tidewater glaciers on the Antarctic Peninsula to ice-shelf removal occurs over timescales ranging from sub-annual to decadal.

An evaluation of sponge-associated amphipods from the Antarctic Peninsula

2009 ◽  
Vol 21 (6) ◽  
pp. 579-589 ◽  
Author(s):  
Margaret O. Amsler ◽  
James B. Mcclintock ◽  
Charles D. Amsler ◽  
Robert A. Angus ◽  
Bill J. Baker
Keyword(s):  
Antarctic Peninsula ◽  
Energy Flow ◽  
Benthic Communities ◽  
Diversity Indices ◽  
Amphipod Species ◽  
Western Antarctic Peninsula ◽  
Gut Content ◽  
Algal Communities ◽  
Host Relationships ◽  
The Antarctic

AbstractNearshore marine benthic algal communities along the western Antarctic Peninsula harbour extremely high densities of amphipods that probably play important roles in nutrient and energy flow. This study extends our evaluation of the importance of amphipods in the nearshore Antarctic Peninsular benthic communities and focuses on sponge associations. We found a mean density of 542 amphipods per litre (L) sponge for twelve species of ecologically dominant sponges. The highest mean density (1295 amphipods per L sponge) occurred withDendrilla membranosaPallas. The amphipod community associated with the 12 sponges was diverse (38 species), with mean species richness values ranging from two to eight species. Mean Shannon diversity indices (H’) ranged from 0.52 to 1.49. Amphipods did not appear to have obligate host relationships. Qualitative gut content analyses indicated that 12 of the 38 amphipod species were found with sponge spicules in their guts. However, only one of the amphipods,Echiniphimedia hodgsoniWalker, had considerable amounts of spicules in the gut. Organic lipophilic and hydrophilic extracts of the twelve sponges were presented in alginate food disks to a sympatric omnivorous amphipod in feeding bioassays and extracts of only two sponges deterred feeding.

The abundance and distribution of echinoderms in nearshore hard-bottom habitats near Anvers Island, western Antarctic Peninsula

2012 ◽  
Vol 24 (6) ◽  
pp. 554-560 ◽  
Author(s):  
Brittny A. White ◽  
James McClintock ◽  
Charles D. Amsler ◽  
Christopher L. Mah ◽  
Margaret O. Amsler ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Positive Relationship ◽  
Western Antarctic Peninsula ◽  
Benthic Production ◽  
Odontaster Validus ◽  
Sterechinus Neumayeri ◽  
Significant Relationships ◽  
Inherent Vulnerability ◽  
Abundance And Distribution ◽  
The Antarctic

AbstractEchinoderms are well represented in nearshore hard-bottom (< 100 m depth) habitats along the Antarctic Peninsula where they are presumably important contributors to benthic production, carbon flow, and determinants of community structure. The present study assesses the densities of echinoderms at shallow depths (2–15 m) at five sampling sites within three kilometres of Anvers Island on the central western Antarctic Peninsula. The asteroids Odontaster validus, Granaster nutrix, Lysasterias perrieri and Adelasterias papillosa, two ophiuroids in the Amphiuridae, the holothuroids Psolicrux coatsi and Psolus carolineae and one representative of the Cucumaridae, and the regular echinoid Sterechinus neumayeri were enumerated. Mean total echinoderm densities were high (34.9 individuals m-2) and ranged from 21.9 individuals m-2 for asteroids to 2.7 individuals m-2 for holothuroids. With the exception of a positive relationship between the abundance of the regular echinoid Sterechinus neumayeri and the biomass of the brown alga Himanthothallus grandifolius, no significant relationships were found between the abundance of asteroids, ophiuroids, or holothuroids and two species of brown algae or three algal ecotypes. The present study indicates nearshore hard-bottom echinoderms are important in the carbon cycle and their inherent vulnerability to ocean acidification may have community-level impacts.

Morphology of Australoneis gen. nov. and A. frenguelliae comb. nov. (Achnanthales, Bacillariophyta) from the Antarctic Peninsula

Phytotaxa ◽  
2021 ◽  
Vol 513 (2) ◽  
pp. 81-98
Author(s):  
JOSÉ M. GUERRERO ◽  
CATHERINE RIAUX-GOBIN ◽  
JUAN I. DEBANDI ◽  
KATHARINA ZACHER ◽  
MARIA LILIANA QUARTINO ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Antarctic Peninsula ◽  
New Genus ◽  
Light And Electron Microscopy ◽  
Benthic Diatoms ◽  
Western Antarctic Peninsula ◽  
Potter Cove ◽  
The Antarctic

Based on marine benthic diatoms collected at Potter Cove (Western Antarctic Peninsula), we present a detailed study, using both light and electron microscopy, of the morphology of Campyloneis frenguelliae, a species recently transferred from Cocconeis. Ultrastructural observations revealed a combination of new and unusual features within the Achnanthales: a raphe valve with different areolation patterns, a hollow valvocopula with no apparent fimbriae, and a sternum valve externally ornamented by an embossed structure, areolae occluded by hymenes mostly supported by one short peg, and multiple marginal pores that open internally into shallow valve depressions. In view of these unique set of features, we describe Australoneis gen. nov. to include Australoneis frenguelliae comb. nov. and designate a sample from Potter Cove as epitype of the latter. The main characteristics of the new genus are compared to those of its closely allied Cocconeis, Campyloneis, Xenococconeis and Amphicocconeis.

scholarly journals Climate change and the marine ecosystem of the western Antarctic Peninsula

2006 ◽  
Vol 362 (1477) ◽  
pp. 149-166 ◽  
Author(s):  
Andrew Clarke ◽  
Eugene J Murphy ◽  
Michael P Meredith ◽  
John C King ◽  
Lloyd S Peck ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Food Web ◽  
Antarctic Peninsula ◽  
Sublethal Effects ◽  
Marine Ecosystem ◽  
Ecological Interactions ◽  
Western Antarctic Peninsula ◽  
Ice Dynamics ◽  
The Antarctic

The Antarctic Peninsula is experiencing one of the fastest rates of regional climate change on Earth, resulting in the collapse of ice shelves, the retreat of glaciers and the exposure of new terrestrial habitat. In the nearby oceanic system, winter sea ice in the Bellingshausen and Amundsen seas has decreased in extent by 10% per decade, and shortened in seasonal duration. Surface waters have warmed by more than 1 K since the 1950s, and the Circumpolar Deep Water (CDW) of the Antarctic Circumpolar Current has also warmed. Of the changes observed in the marine ecosystem of the western Antarctic Peninsula (WAP) region to date, alterations in winter sea ice dynamics are the most likely to have had a direct impact on the marine fauna, principally through shifts in the extent and timing of habitat for ice-associated biota. Warming of seawater at depths below ca 100 m has yet to reach the levels that are biologically significant. Continued warming, or a change in the frequency of the flooding of CDW onto the WAP continental shelf may, however, induce sublethal effects that influence ecological interactions and hence food-web operation. The best evidence for recent changes in the ecosystem may come from organisms which record aspects of their population dynamics in their skeleton (such as molluscs or brachiopods) or where ecological interactions are preserved (such as in encrusting biota of hard substrata). In addition, a southwards shift of marine isotherms may induce a parallel migration of some taxa similar to that observed on land. The complexity of the Southern Ocean food web and the nonlinear nature of many interactions mean that predictions based on short-term studies of a small number of species are likely to be misleading.

scholarly journals Transport of warm Upper Circumpolar Deep Water onto the western Antarctic Peninsula continental shelf

Ocean Science ◽  
2012 ◽  
Vol 8 (4) ◽  
pp. 433-442 ◽  
Author(s):  
D. G. Martinson ◽  
D. C. McKee
Keyword(s):  
Continental Shelf ◽  
Antarctic Peninsula ◽  
Deep Water ◽  
Antarctic Circumpolar Current ◽  
Western Antarctic Peninsula ◽  
Dominant Mechanism ◽  
Circumpolar Deep Water ◽  
Marguerite Bay ◽  
Circumpolar Current ◽  
The Antarctic

Abstract. Five thermistor moorings were placed on the continental shelf of the western Antarctic Peninsula (between 2007 and 2010) in an effort to identify the mechanism(s) responsible for delivering warm Upper Circumpolar Deep Water (UCDW) onto the broad continental shelf from the Antarctic Circumpolar Current (ACC) flowing over the adjacent continental slope. Historically, four mechanisms have been suggested: (1) eddies shed from the ACC, (2) flow into the cross-shelf-cutting canyons with overflow onto the nominal shelf, (3) general upwelling, and (4) episodic advective diversions of the ACC onto the shelf. The mooring array showed that for the years of deployment, the dominant mechanism is eddies; upwelling may also contribute but to an unknown extent. Mechanism 2 played no role, though the canyons have been shown previously to channel UCDW across the shelf into Marguerite Bay. Mechanism 4 played no role independently, though eddies may be advected within a greater intrusion of the background flow.

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