Antarctic Science - Current Issue

Volume 20 Issue 06

Mon, 01 Dec 2008 00:00:00 GMT

Antarctic Science, Volume 20 Issue 06

Antarctic Science provides a truly international forum for the broad spread of studies that increasingly characterise scientific research in the Antarctic. Whilst emphasising interdisciplinary work, the journal publishes papers from environmental management to biodiversity, from volcanoes to icebergs, and from oceanography to the upper atmosphere. No other journal covers such a wide range of Antarctic scientific studies. The journal attracts papers from all countries currently undertaking Antarctic research. It publishes both review and data papers with no limits on length, two page short notes on technical developments and recent discoveries, and book reviews. These, together with an editorial discussing broader aspects of science, provide a rich and varied mixture of items to interest researchers in all areas of science. One issue each year is normally devoted to a specific theme or papers from a major meeting. The journal will be published in full colour from 2009 onwards.

Naming the parts

Editorial
David W.H. Walton,
Antarctic Science, Volume 20 Issue 06 , pp 519-519

Abstract

Response of antioxidant defence systems to thermal stress in the Antarctic clam Laternula elliptica

Research Articles
Hyun Park, In-Young Ahn, Kyung-Il Park, Seunghun Hyun,
Antarctic Science, Volume 20 Issue 06 , pp 521-526

Abstract
The effects of thermal stress on antioxidant defences in tissues of the Antarctic clam Laternula elliptica were evaluated and the activities of some antioxidant enzymes, and levels of total glutathione (GSH) and protein carbonyl (PC) in digestive gland and gill over 0 C) were measured. Superoxide dismutase activity was slightly higher after one day of thermal stress, although catalase activity was not altered significantly in either digestive gland or gill tissues. Thermal stress was associated with a significant increase in the activity of GSH-related antioxidant enzymes. Glutathione peroxidase and glutathione reductase activities increased up to 1.8- and 2.0-fold, respectively, after two days of thermal stress. Glutathione S-transferase activity drastically increased, to over 3.4- and 4.2-fold in digestive gland and gill, respectively, and remained high on day four. GSH levels also increased in both tissues and remained high on day four. PC content, a marker of protein oxidation, increased after two days of thermal stress. There is evidence that GSH-related antioxidant defence plays a significant role in relation to potential toxicity from reactive oxygen species during thermal stress.

Deep dehydration of Umbilicaria aprina thalli observed by proton NMR and sorption isotherm

Research Articles
H. Harańczyk, M. Bacior, M.A. Olech,
Antarctic Science, Volume 20 Issue 06 , pp 527-535

Abstract
The initial stages of Umbilicaria aprina Nyl. hydration (starting from the hydration level 0.004) were observed using hydration kinetics, sorption isotherm and proton NMR. The thalli were hydrated from gaseous phase. The total saturation hydration level obtained at the relative humidity p/p0 = 100% was 0.009. The hydration courses revealed i) a fraction of very tightly bound water ( 0.011, short hydration time constant, thyd), ii) a fraction of tightly bound water [ 0.038, thyd = (4.7 1.9) h] for higher values of target humidity. The sorption isotherm of U. aprina was fitted well using Dent model. The relative mass of water saturating primary binding sites was sealed water fraction trapped in pores of the thallus.

Biological implications of low condition factor “axe handle” specimens of the Antarctic toothfish, Dissostichus mawsoni , from the Ross Sea

Research Articles
J.M. Fenaughty, Joseph T. Eastman, Bruce D. Sidell,
Antarctic Science, Volume 20 Issue 06 , pp 537-551

Abstract
We evaluated the condition factor (K), an index of weight per unit length, in a sample of 49 761 longline-caught specimens of Antarctic toothfish, Dissostichus mawsoni, from the Ross Sea. Our sample consisted of specimens from northern (60 S) and southern (70 S) regions. Fifty percent of the northern sample and 4.9% of the southern sample were large individuals with a low condition factor (Kah axe handle (ah) morphology with a notably thinner trunk. In the northern sample 55.4% of the males and 43.2% of the females were less than Kah. In the southern region 5.3% of the males and 4.5% of the females were less than Kah. The axe handle morphology is attributable to the metabolic loss of muscular and subcutaneous lipid stores, and probably proteins, from white muscle. Our discussion considers energy metabolism as related to migration, feeding and reproduction. We suggest that migration, a life history trait of the phyletically basal notothenioid clades Pseudaphritis and Eleginops, persists in D. mawsoni. The spawning migration from the southern shelf to ridges and seamounts in the north may reflect fidelity to historic spawning grounds. As evidenced by the axe handle specimens neutral buoyancy of large D. mawsoni may be ephemeral, fluctuating over the course of adult life.

A preliminary floristic classification of southern and northern Victoria Land vegetation, continental Antarctica

Research Articles
Nicoletta Cannone, Rodney Seppelt,
Antarctic Science, Volume 20 Issue 06 , pp 553-562

Abstract
This paper proposes a new objectively-generated vegetation classification for southern and northern Victoria Land (continental Antarctica) based on the floristic composition of the plant communities. The new classification aims to integrate the existing physiognomic classification of the cryptogamic Antarctic tundra, provide useful data on floristic composition and distribution of the vegetation occurring in southern and northern Victoria Land, and develop a suitable tool allowing easy comparison of syntaxa from different locations. Field data from 26 sites along a latitudinal gradient (72 77 S) were analysed by a hierarchical classification integrated with multivariate statistics, including indirect ecological information (Principal Component Analysis). Similarity of the identified groups was assessed through the Jaccard similarity index. The new classification is compatible with previous ones and is widely applicable to Victoria Land and includes previous classification. This standardized approach relates plant communities to their floristic composition and provides a basis for relating vegetation composition to environmental gradients and to patterns of vegetation dynamics and succession which are still poorly understood in Antarctica.

Short Note: Life history of the Antarctic sea star Labidiaster annulatus (Asteroidea: Labidiasteridae) revealed by DNA barcoding

Research Articles
Alexis M. Janosik, Andrew R. Mahon, Rudolf S. Scheltema, Kenneth M. Halanych,
Antarctic Science, Volume 20 Issue 06 , pp 563-564

Abstract

The role of thermal contraction crack polygons in cold-desert fluvial systems

Research Articles
Joseph S. Levy, James W. Head, David R. Marchant,
Antarctic Science, Volume 20 Issue 06 , pp 565-579

Abstract
Thermal contraction crack polygons modify the generation, transport, and storage of water in Wright Valley gullies. Water generation is contributed to by trapping of windblown snow in polygon troughs. Water transport is modified by changes to the ice-cement table and active layer topography caused by polygon trough formation. Water storage is modified by sediment grain-size distribution within polygons in gully distal hyporheic zones. Patterned ground morphological variation can serve as an indicator of fluvial modification, ranging from nearly unmodified composite-wedge polygons to polygons forming in association with gully channels. Thermal contraction crack polygons may also constrain the gully formation sequence, suggesting the continuous presence of permafrost beneath the Wright Valley gullies during the entire period of gully emplacement. This analysis provides a framework for understanding the relationships between polygons and gullies observed on Mars. If comparable stratigraphic relationships can be documented, the presence of an analogous impermeable ice-cemented layer beneath the gullies can be inferred, suggesting an atmospheric source for Martian gully-carving fluids.

The last deglaciation of Cape Adare, northern Victoria Land, Antarctica

Research Articles
Joanne S. Johnson, Claus-Dieter Hillenbrand, John L. Smellie, Sergio Rocchi,
Antarctic Science, Volume 20 Issue 06 , pp 581-587

Abstract
We present two 10Be exposure ages from erratic boulders at Cape Adare, northern Victoria Land. The exposure ages obtained suggest that Cape Adare was covered by ice during the last glacial period, and the younger age points to deglaciation around 16.2 ka. Comparison of our younger 10Be exposure age with published radiocarbon dates for Ad 3 kyr before present) lagged behind the deglaciation by at least 11.5 kyr. These observations indicate that penguin colonization did not occur until several thousand years after ice free ground became available.

Short Note: An intriguing penguin bone from the Late Eocene of Seymour Island, Antarctic Peninsula

Research Articles
Piotr Jadwiszczak,
Antarctic Science, Volume 20 Issue 06 , pp 589-590

Abstract

Short Note: Late Miocene marine trace fossils from James Ross Island

Research Articles
Anna E. Nelson, John L. Smellie, Mark Williams, Jan Zalasiewicz,
Antarctic Science, Volume 20 Issue 06 , pp 591-592

Abstract

Impact of the B-15 iceberg “stranding event” on the physical and biological properties of sea ice in McMurdo Sound, Ross Sea, Antarctica

Research Articles
J.-P. Remy, S. Becquevort, T.G. Haskell, J.-L. Tison,
Antarctic Science, Volume 20 Issue 06 , pp 593-604

Abstract
Ice cores were sampled at four stations in McMurdo Sound (Ross Sea) between 1999 and 2003. At the beginning of year 2000, a very large iceberg (B-15) detached itself from the Ross Ice Shelf and stranded at the entrance of the Sound, preventing the usual oceanic circulation purging of the annual sea ice cover from this area. Ice textural studies showed that a second year sea ice cover was built-up at three out of the four stations: ice thickness increased to about 3 m. Repeated alternation of columnar and platelet ice appeared, and bulk salinity showed a strong decrease, principally in the upper part of the ice sheet, with associated brine volume decrease. Physical modification influenced the biology as well. By decreasing the light and space available for organisms in the sea ice cover, the stranding of B-15 has i) hampered autotrophic productivity, with chlorophyll a concentration and algae biomass significantly lower for second year ice stations, and ii) affected trophic relationships such as the bacterial biomass/chl a concentration correlation, or the autotrophic to heterotrophic ratio.

First space-borne high-spatial-resolution optical imagery of the Antarctic from Formosat-2

Research Articles
Cheng-Chien Liu, Yueh-Cheng Chang, Stefani Huang, Frank Wu, An-Ming Wu, Soushi Kato, Yasushi Yamaguchi,
Antarctic Science, Volume 20 Issue 06 , pp 605-606

Abstract

Antarctic Bioprospecting Edited by Alan D. Hemmings & Michelle Rogan-Finnemore Gateway Antarctica Special Publication, Christchurch, 2005 ISBN 0-476-01647-9, 351 pp, NZ$65

Book Reviews
Kevin Hughes,
Antarctic Science, Volume 20 Issue 06 , pp 607-608

Abstract

Antarctic Ecology: From Genes to Ecosystems. Part 2: Evolution, Diversity and Function Edited by A.D. Rogers, E.J. Murphy, A. Clarke & N.M. Johnston Philosophical Transactions of The Royal Society Series B, 362, 2183–2378, 2007.

Book Reviews
Kevin J. Gaston,
Antarctic Science, Volume 20 Issue 06 , pp 608-609

Abstract

Deep-Time Perspectives on Climate Change: Marrying the Signal from Computer Models and Biological Proxies Edited by M. Williams, A.M. Haywood, F.J. Gregory & D.N. Schmidt The Geological Society, 2007. ISBN 1-86239-240-4, £95 (fellows £57)

Book Reviews
Ulrich Salzmann,
Antarctic Science, Volume 20 Issue 06 , pp 609-610

Abstract

Snow and Climate: Physical Processes, Surface Energy Exchange and Modeling Edited by R.L. Armstrong & E. Brun Cambridge University Press, Cambridge, 2008 ISBN 9780521854542, 256 pages, £65

Book Reviews
Michiel van den Broeke,
Antarctic Science, Volume 20 Issue 06 , pp 610-611

Abstract

Trends in Antarctic Terrestrial and Limnetic Ecosystems: Antarctica as a global indicator Edited by D.M. Bergstrom, P. Convey & A.H.L. Huiskes Springer, Dordrecht, 2006. ISBN 978-1-4020-5276-7, 369 pp, US$119

Book Reviews
D.W.H. Walton,
Antarctic Science, Volume 20 Issue 06 , pp 611-612

Abstract