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.

Cold tolerance of the Antarctic springtail Gomphiocephalus hodgsoni (Collembola, Hypogastruridae)

2001 ◽  
Vol 13 (3) ◽  
pp. 271-279 ◽  
Author(s):  
Brent J. Sinclair ◽  
Heidi Sjursen
Keyword(s):  
Cold Tolerance ◽  
Thermal Environment ◽  
Strong Relationship ◽  
Dry Weight ◽  
Glycerol Content ◽  
Recrystallization Inhibition ◽  
Low Levels ◽  
Inhibition Studies ◽  
The Antarctic ◽  
The Relationship

Cold tolerance of the springtail Gomphiocephalus hodgsoni Carpenter (Collembola: Hypogastruridae) was studied at Cape Bird, Ross Island, Antarctica (77°13′S, 166°26′E). Microclimate temperatures indicate a highly seasonal thermal environment, with winter minima <–39°C. Snow cover significantly buffers both minimum temperatures and cooling rates. Gomphiocephalus hodgsoni survives low temperatures by avoiding freezing. Mean low group supercooling points (SCPs) ranged from –35.4°C in October to –28.3°C in January. The lowest SCP measured was –38.0°C. The high SCP group was very small, making up only 18% of the population in January. In October, G. hodgsoni had a very high glycerol content (>80 μg mg−1 dry weight), although this declined rapidly to low levels (c. 7–10 μg mg−1 dry weight) in January. Quantities of glucose and trehalose were low during October, but steadily increased throughout the summer. Haemolymph osmolality was exceptionally high (up to 1755 mOsm kg−1) at the end of November, but this rapidly declined to c. 500 mOsm kg−1 by late December. The presence of thermal hystersis proteins was indicated by both osmometry on haemolymph samples and recrystallization inhibition studies of springtail homogenates. There was a strong relationship between glycerol content and SCP, but the relationship between haemolymph osmolality, SCP and carbohydrates is uncertain.

scholarly journals A description and summary of the Antarctic Humpback Whale Catalogue

2020 ◽  
pp. 95-99
Author(s):  
Judith Allen ◽  
Carole Carlson ◽  
Peter T. Stevick
Keyword(s):  
South America ◽  
Southern Ocean ◽  
Antarctic Peninsula ◽  
Humpback Whale ◽  
Humpback Whales ◽  
Western Coast ◽  
Long Distance ◽  
Dorsal Fin ◽  
Feeding Area ◽  
The Antarctic

The Antarctic Humpback Whale Catalogue (AHWC) is an international collaborative project investigating movement patterns of humpback whales in the Southern Ocean and corresponding lower latitude waters. The collection contains records contributed by 261 researchers and opportunistic sources. Photographs come from all of the Antarctic management areas, the feeding grounds in southern Chile and also most of the known or suspected low-latitude breeding areas and span more than two decades. This allows comparisons to be made over all of the major regions used by  Southern Hemisphere humpback whales. The fluke, left dorsal fin/flank and right dorsal fin/flank collections represent 3,655, 413 and 407 individual whales respectively. There were 194 individuals resighted in more than one year, and 82 individuals resighted in more than one region. Resightings document movement along the western coast of South America and movement between the Antarctic Peninsula and western coast of South America and Central America. A single individual from Brazil was resighted off South Georgia, representing the first documented link between the Brazilian breeding ground and any feeding area. A second individual from Brazil was resighted off Madagascar, documenting long distance movement of a female between non-adjacent breeding areas. Resightings also include two matches between American Samoa and the Antarctic Peninsula, documenting the first known feeding site for American Somoa and setting a new long distance seasonal migration record. Three matches between Sector V and eastern Australia support earlier evidence provided by Discovery tags. Multiple resightings of individuals in the Antarctic Peninsula during more than one season indicate that humpback whales in this area show some degree of regional feeding area fidelity. The AHWC provides a powerful non-lethal and non-invasive tool for investigating the movements and population structure of the whales utilising the Southern Ocean Sanctuary. Through this methodical, coordinated comparison and maintenance of collections from across the hemisphere, large-scale movement patterns may be examined, both within the Antarctic, and from the Antarctic to breeding grounds at low latitudes.

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.

Parasites and low temperatures

Parasitology ◽  
1999 ◽  
Vol 119 (S1) ◽  
pp. S7-S17 ◽  
Author(s):  
D. A. Wharton
Keyword(s):  
Life Cycle ◽  
Cold Tolerance ◽  
Low Temperatures ◽  
Cold Hardiness ◽  
Free Living ◽  
Rate Of Growth ◽  
Subzero Temperatures ◽  
Growth Development ◽  
Epidemiological Significance

SUMMARYLow temperatures affect the rate of growth, development and metabolism of parasites and when temperatures fall below 0°C may expose the parasite to the potentially lethal risk of freezing. Some parasites have mechanisms, such as diapause, which synchronise their life cycle with favourable seasons and the availability of hosts. Parasites of endothermic hosts are protected from low temperatures by the thermoregulatory abilities of their host. Free-living and off-host stages, however, may be exposed to subzero temperatures and both freezing-tolerant and freeze-avoiding strategies of cold hardiness are found. Parasites of ectothermic hosts may be exposed to subzero temperatures within their hosts. They can rely on the cold tolerance adaptations of their host or they may develop their own mechanisms. Exposure to low temperatures may occur within the carcass of the host and this may be of epidemiological significance if the parasite can be transmitted via the consumption of the carcass.

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.

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