scholarly journals The Timing of reproduction in the Antarctic limpet Nacella concinna (srebel, 1908) (Patellidae) at Signy Island, in relation to environmental variables

1998 ◽  
Vol 64 (1) ◽  
pp. 123-127 ◽  
Author(s):  
D. Stanwell-Smith ◽  
A. Clarke
Keyword(s):  
Environmental Variables ◽  
Timing Of Reproduction ◽  
Signy Island ◽  
The Antarctic

Recent Rapid Climate Changes in Antarctic and their Influence on Low Diversity Ecosystems

2010 ◽  
Vol 17 (1) ◽  
pp. 17-30 ◽  
Author(s):  
Katarzyna J. Chwedorzewska
Keyword(s):  
Environmental Variables ◽  
Climate Changes ◽  
Biological Significance ◽  
Global Changes ◽  
Factors Affecting ◽  
Low Diversity ◽  
Main Factors ◽  
The Antarctic ◽  
High Diversity ◽  
Temperature Water

ABSTRACTThe geographic position, astronomic factors (e.g. the Earth’s maximum distance from the Sun during winter), ice cover and altitude are the main factors affecting the climate of the Antarctic, which is the coldest place on Earth. Parts of Antarctica are facing the most rapid rates of anthropogenic climate change currently seen on the planet. Climate changes are occurring throughout Antarctica, affecting three major groups of environmental variables of considerable biological significance: temperature, water, UV-B radiation.Low diversity ecosystems are expected to be more vulnerable to global changes than high diversity ecosystems

scholarly journals Driving Forces of Circum-Antarctic Glacier and Ice Shelf Front Retreat over the Last Two Decades

2020 ◽  
Author(s):  
Celia A. Baumhoer ◽  
Andreas J. Dietz ◽  
Christof Kneisel ◽  
Heiko Paeth ◽  
Claudia Kuenzer
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Air Temperature ◽  
Environmental Variables ◽  
Sea Surface ◽  
Ice Shelf ◽  
Antarctic Ice Sheet ◽  
Ice Shelves ◽  
The Antarctic

Abstract. The safety band of Antarctica consisting of floating glacier tongues and ice shelves buttresses ice discharge of the Antarctic Ice Sheet. Recent disintegration events of ice shelves and glacier retreat indicate a weakening of this important safety band. Predicting calving front retreat is a real challenge due to complex ice dynamics in a data-scarce environment being unique for each ice shelf and glacier. We explore to what extent easy to access remote sensing and modelling data can help to define environmental conditions leading to calving front retreat. For the first time, we present a circum-Antarctic record of glacier and ice shelf front retreat over the last two decades in combination with environmental variables such as air temperature, sea ice days, snowmelt, sea surface temperature and wind direction. We find that the Antarctic ice sheet area shrank 29,618 ± 29 km2 in extent between 1997–2008 and gained an area of 7,108 ± 144.4 km2 between 2009 and 2018. Retreat concentrated along the Antarctic Peninsula and West Antarctica including the biggest ice shelves Ross and Ronne. Glacier and ice shelf retreat comes along with one or several changes in environmental variables. Decreasing sea ice days, intense snow melt, weakening easterlies and relative changes in sea surface temperature were identified as enabling factors for retreat. In contrast, relative increases in air temperature did not correlate with calving front retreat. To better understand drivers of glacier and ice shelf retreat it is of high importance to analyse the magnitude of basal melt through the intrusion of warm Circumpolar Deep Water (CDW) driven by strengthening westerlies and to further assess surface hydrology processes such as meltwater ponding, runoff and lake drainage.

The effectiveness of Virkon® S disinfectant against an invasive insect and implications for Antarctic biosecurity practices

2020 ◽  
pp. 1-9 ◽  
Author(s):  
Jesamine C. Bartlett ◽  
Richard James Radcliffe ◽  
Pete Convey ◽  
Kevin A. Hughes ◽  
Scott A.L. Hayward
Keyword(s):  
Salt Water ◽  
Hot Water ◽  
Antarctic Region ◽  
Invasive Insect ◽  
Signy Island ◽  
Antarctic Treaty ◽  
Biosecurity Practices ◽  
Water Treatments ◽  
The Antarctic ◽  
Maximum Threshold

Abstract The flightless midge Eretmoptera murphyi is thought to be continuing its invasion of Signy Island via the treads of personnel boots. Current boot-wash biosecurity protocols in the Antarctic region rely on microbial biocides, primarily Virkon® S. As pesticides have limited approval for use in the Antarctic Treaty area, we investigated the efficacy of Virkon® S in controlling the spread of E. murphyi using boot-wash simulations and maximum threshold exposures. We found that E. murphyi tolerates over 8 h of submergence in 1% Virkon® S. Higher concentrations increased effectiveness, but larvae still exhibited > 50% survival after 5 h in 10% Virkon® S. Salt and hot water treatments (without Virkon® S) were explored as possible alternatives. Salt water proved ineffective, with mortality only in first-instar larvae across multi-day exposures. Larvae experienced 100% mortality when exposed for 10 s to 50°C water, but they showed complete survival at 45°C. Given that current boot-wash protocols alone are an ineffective control of this invasive insect, we advocate hot water (> 50°C) to remove soil, followed by Virkon® S as a microbial biocide on ‘clean’ boots. Implications for the spread of invasive invertebrates as a result of increased human activity in the Antarctic region are discussed.

scholarly journals Surviving the Antarctic Winter—Life Stage Cold Tolerance and Ice Entrapment Survival in The Invasive Chironomid Midge Eretmoptera murphyi

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 147 ◽  
Author(s):  
Jesamine C. Bartlett ◽  
Peter Convey ◽  
Scott A. L. Hayward
Keyword(s):  
Cold Tolerance ◽  
Cold Hardiness ◽  
Life Stage ◽  
Western Coast ◽  
Critical Determinant ◽  
Signy Island ◽  
Detailed Assessment ◽  
Freeze Tolerant ◽  
The Antarctic ◽  
Assessment Of Stress

An insect’s ability to tolerate winter conditions is a critical determinant of its success. This is true for both native and invasive species, and especially so in harsh polar environments. The midge Eretmoptera murphyi (Diptera, Chironomidae) is invasive to maritime Antarctic Signy Island, and the ability of fourth instar larvae to tolerate freezing is hypothesized to allow the species to extend its range further south. However, no detailed assessment of stress tolerance in any other life stage has yet been conducted. Here, we report that, although larvae, pupae and adults all have supercooling points (SCPs) of around −5 °C, only the larvae are freeze-tolerant, and that cold-hardiness increases with larval maturity. Eggs are freeze-avoiding and have an SCP of around −17 °C. At −3.34 °C, the CTmin activity thresholds of adults are close to their SCP of −5 °C, and they are likely chill-susceptible. Larvae could not withstand the anoxic conditions of ice entrapment or submergence in water beyond 28 d. The data obtained here indicate that the cold-tolerance characteristics of this invasive midge would permit it to colonize areas further south, including much of the western coast of the Antarctic Peninsula.

scholarly journals The scale of the whale: using video-tag data to evaluate sea-surface ice concentration from the perspective of individual Antarctic minke whales

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Jacob M. J. Linsky ◽  
Nicole Wilson ◽  
David E. Cade ◽  
Jeremy A. Goldbogen ◽  
David W. Johnston ◽  
...  
Keyword(s):  
Satellite Imagery ◽  
Antarctic Peninsula ◽  
Environmental Variables ◽  
Cloud Cover ◽  
Video Data ◽  
Environmental Data ◽  
Minke Whales ◽  
Ice Concentration ◽  
Surface Ice ◽  
The Antarctic

Abstract Background Advances in biologging technology allow researchers access to previously unobservable behavioral states and movement patterns of marine animals. To relate behaviors with environmental variables, features must be evaluated at scales relevant to the animal or behavior. Remotely sensed environmental data, collected via satellites, often suffers from the effects of cloud cover and lacks the spatial or temporal resolution to adequately link with individual animal behaviors or behavioral bouts. This study establishes a new method for remotely and continuously quantifying surface ice concentration (SIC) at a scale relevant to individual whales using on-animal tag video data. Results Motion-sensing and video-recording suction cup tags were deployed on 7 Antarctic minke whales (Balaenoptera bonaerensis) around the Antarctic Peninsula in February and March of 2018. To compare the scale of camera-tag observations with satellite imagery, the area of view was simulated using camera-tag parameters. For expected conditions, we found the visible area maximum to be ~ 100m2 which indicates that observations occur at an equivalent or finer scale than a single pixel of high-resolution visible spectrum satellite imagery. SIC was classified into one of six bins (0%, 1–20%, 21–40%, 41–60%, 61–80%, 81–100%) by two independent observers for the initial and final surfacing between dives. In the event of a disagreement, a third independent observer was introduced, and the median of the three observer’s values was used. Initial results (n = 6) show that Antarctic minke whales in the coastal bays of the Antarctic Peninsula spend 52% of their time in open water, and only 15% of their time in water with SIC greater than 20%. Over time, we find significant variation in observed SIC, indicating that Antarctic minke occupy an extremely dynamic environment. Sentinel-2 satellite-based approaches of sea ice assessment were not possible because of persistent cloud cover during the study period. Conclusion Tag-video offers a means to evaluate ice concentration at spatial and temporal scales relevant to the individual. Combined with information on underwater behavior, our ability to quantify SIC continuously at the scale of the animal will improve upon current remote sensing methods to understand the link between animal behavior and these dynamic environmental variables.

Discussion on the preceding papers

1967 ◽  
Vol 252 (777) ◽  
pp. 209-212
Keyword(s):  
Elephant Seal ◽  
Short Term ◽  
Marginal Population ◽  
Secular Changes ◽  
Long Period ◽  
Signy Island ◽  
Pack Ice ◽  
Seal Population ◽  
Ice Conditions ◽  
The Antarctic

J . E. Smith. May I ask, at the outset of our discussion of this morning’s papers, whether there is any evidence of long- or short-term secular changes of climate in the Signy Island area? G. de Q. Robin. J. A. Heap, in preparing an ice atlas of the Antarctic seas, drew upon the long period of meteorological records from the Argentine station ‘Orcadas’ on Laurie Island, South Orkney Island, and from the British station at Grytviken, South Georgia. He was able to show that in the late 1920s there were several years with mean annual temperatures 1 or 2 degC below average, while in the 1950-60 period moderate fluctuations in climate could be associated with fluctuations in the pack ice. M. W. Holdgate. Because of the lack of suitable ‘indicator species’ in the land flora, pollen analysis from the Antarctic zone is not likely to help in this problem. However, some evidence of climatic change may be derived from the fluctuating fortunes of the small elephant seal population at Signy Island. When first studied by R. M. Laws in 1948 this was producing 80 to 100 pups annually: latterly numbers have fallen off dramatically and in some seasons only four or five have been born. This is a marginal population of a species not penetrating deeply within the ice zone, and hence will probably be a good indicator of changing climate and ice conditions.

The first record of a myxomycete from subantarctic Macquarie Island

1992 ◽  
Vol 4 (4) ◽  
pp. 431-432 ◽  
Author(s):  
Steven L. Stephenson ◽  
Rodney D. Seppelt ◽  
Gary A. Laursen
Keyword(s):  
Antarctic Peninsula ◽  
Boreal Forests ◽  
Woody Debris ◽  
First Record ◽  
South Georgia ◽  
Orkney Islands ◽  
Signy Island ◽  
Slime Moulds ◽  
Plasmodial Slime Moulds ◽  
The Antarctic

Myxomycetes (plasmodial slime moulds) are best known from temperate and boreal forests, where they are commonly found in association with decaying coarse woody debris and leaf litter on the forest floor (Martin & Alexopoulos 1969). There have been only a few reports of myxomycetes from either the continent of Antarctica or the subantarctic islands. In what apparently represents the first record of a myxomycete from the south polar region, Horak (1966) described a new species, Diderma antarcticolum Horak, from material collected on the Antarctic Peninsula (64°53′S, 62°53′W). Later, Ing & Smith (1980,1983) reported Didymium dubium Rost., Lamproderma arcyrioides (Sommerf.) Rost., Stemonitopsis (Comatricha) subcaespitosa (Peck) Nann.- Brem. and Diderma niveum (Rost.) Macbr. from South Georgia (54–55°S, 36–38°W). They also indicated that the latter species was known from Signy Island, South Orkney Islands (60°43′S, 45°36′W) and the Antarctic Peninsula (65°16′S, 64°08′W) as well as South Georgia.

scholarly journals Evaluating Highest-Temperature Extremes in the Antarctic

Eos ◽  
2017 ◽  
Author(s):  
Maria Skansi ◽  
John King ◽  
Matthew Lazzara ◽  
Randall Cerveny ◽  
Jose Stella ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Extremes ◽  
Research Station ◽  
Signy Island ◽  
The Antarctic

The record high temperature for regions south of 60°S latitude is a balmy 19.8°C (67.6°F), recorded 30 January 1982 at a research station on Signy Island.

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