The Antarctic Pack-Ice Ecosystem

Abstract. This study investigates the surface albedo of the sea ice areas adjacent to the Antarctic Peninsula during the austral summer. Aircraft measurements of the surface albedo, which were conducted in the sea ice areas of the Weddell and Bellingshausen Seas show significant differences between these two regions. The averaged surface albedo varied between 0.13 and 0.81. The ice cover of the Bellingshausen Sea consisted mainly of first year ice and the sea surface showed an averaged sea ice albedo of αi = 0.64 ± 0.2 (± standard deviation). The mean sea ice albedo of the pack ice area in the western Weddell Sea was αi = 0.75 ± 0.05. In the southern Weddell Sea, where new, young sea ice prevailed, a mean albedo value of αi = 0.38 ± 0.08 was observed. Relatively warm open water and thin, newly formed ice had the lowest albedo values, whereas relatively cold and snow covered pack ice had the highest albedo values. All sea ice areas consisted of a mixture of a large range of different sea ice types. An investigation of commonly used parameterizations of albedo as a function of surface temperature in the Weddell and Bellingshausen Sea ice areas showed that the albedo parameterizations do not work well for areas with new, young ice.

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The occurrence of the copepods Stephos longipes (Calanoida) and Drescheriella glacialis (Harpacticoida) in summer sea ice in the Weddell Sea, Antarctica

Antarctic Science ◽

10.1017/s0954102001000232 ◽

2001 ◽

Vol 13 (2) ◽

pp. 150-157 ◽

Cited By ~ 17

Author(s):

Sigrid B. Schnack-Schiel ◽

David N. Thomas ◽

Christian Haas ◽

Gerhard S. Dieckmann ◽

Ruth Alheit

Keyword(s):

Total Population ◽

Calanoid Copepod ◽

Late Summer ◽

Geographic Area ◽

Weddell Sea ◽

Air Temperatures ◽

Pack Ice ◽

Stephos Longipes ◽

Surface Ice ◽

The Antarctic

In January to March 1997, a RV Polarstern cruise that transected the Weddell Sea resulted in samples being taken in thick pack ice in the south-eastern Weddell Sea and then along the marginal ice edge towards the Antarctic Peninsula. Several ice types were thus sampled over a wide geographic area during late summer/early autumn. Common features of the first warm period was the occurrence of surface ponds, and that many floes had quasi-continuous horizontal gaps, underlying a layer of ice and metamorphic snow. With the onset of cold air temperatures in late February the gaps rapidly refroze. The calanoid copepod Stephos longipes occurred in all habitats encountered and showed highest numbers in the surface ice in summer, in the gap water during both seasons and in the refrozen gap water in autumn. Nauplii outnumbered copepodids in the surface ice and refrozen gap water, while in the gap water copepodids, mainly stages CI–CIII in summer and CII–CIV in autumn, comprised about 70% of the total population. The harpacticoid species Drescheriella glacialis did not occur in all habitats and was missing in surface ponds and new ice. Nauplii of D. glacialis were rarely found in gap water, but predominated in the refrozen gaps.

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Bird and mammal life recorded during the Antarctic drift of SY Aurora, 1915–16

Polar Record ◽

10.1017/s0032247400011785 ◽

1990 ◽

Vol 26 (159) ◽

pp. 277-288 ◽

Cited By ~ 5

Author(s):

P. D. Shaughnessy

Keyword(s):

Southern Ocean ◽

Ross Sea ◽

Killer Whales ◽

Food Items ◽

Emperor Penguins ◽

Sea Birds ◽

Pack Ice ◽

Antarctic Expedition ◽

The Antarctic ◽

Blue Whales

AbstractAfter landing the Ross Sea shore party of Shackleton's Imperial Trans-Antarctic Expedition at Cape Evans, McMurdo Sound, SY Aurora drifted for 313 days between May 1915 and March 1916 in the pack iceof the Ross Sea and Southern Ocean. During the drift A. H. Ninnis maintained observations of the fauna. He was out hunting on the pack ice on at least 86 days to augment the ship's slender provisions, taking 289 penguins, 10 other sea birds and 20 seals. He sighted whales on at least 15 days, including killer whales in July and August and four large whales, possibly blue whales, in November. He also noted birds returning south for the breeding season in spring, progress of moult in emperor penguins, pupping of crabeater and leopard seals, and food items of several seals and seabirds. Most of his report is presented here, edited to improve its readability and remove abbreviations; the text is preceded by a brief summary of the fauna seen and followed by footnotes on some of his observations.

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Estimating population status under conditions of uncertainty: the Ross seal in East Antarctica

Antarctic Science ◽

10.1017/s0954102007000879 ◽

2008 ◽

Vol 20 (2) ◽

pp. 123-133 ◽

Cited By ~ 13

Author(s):

Colin J. Southwell ◽

Charles G.M. Paxton ◽

David L. Borchers ◽

Peter L. Boveng ◽

Erling S. Nordøy ◽

...

Keyword(s):

Survey Design ◽

East Antarctica ◽

Population Status ◽

Pack Ice ◽

The Status ◽

Antarctic Treaty ◽

Survey Design And Analysis ◽

The Many ◽

Many Sources ◽

The Antarctic

AbstractThe Ross seal (Ommatophoca rossii) is the least studied of the Antarctic ice-breeding phocids. In particular, estimating the population status of the Ross seal has proved extremely difficult. The Protocol on Environmental Protection to the Antarctic Treaty currently designates the Ross seal as a ‘Specially Protected Species’, contrasting with the IUCN's classification of ‘Least Concern’. As part of a review of the Ross seal's classification under the Protocol, a survey was undertaken in 1999/2000 to estimate the status of the Ross seal population in the pack ice off East Antarctica between 64–150°E. Shipboard and aerial sighting surveys were carried out along 9476 km of transect to estimate the density of Ross seals hauled out on the ice, and satellite dive recorders deployed on a sample of Ross seals to estimate the proportion of time spent on the ice. The survey design and analysis addressed the many sources of uncertainty in estimating the abundance of this species in an effort to provide a range of best and plausible estimates. Best estimates of abundance in the survey region ranged from 41 300–55 900 seals. Limits on plausible estimates ranged from 20 500 (lower 2.5 percentile) to 226 600 (upper 97.5 percentile).

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Discussion on the preceding papers

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1967.0013 ◽

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.

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The treatment of spatial autocorrelation in biological surveys: the case of line transect surveys

Antarctic Science ◽

10.1017/s0954102002000664 ◽

2002 ◽

Vol 14 (2) ◽

pp. 115-122 ◽

Cited By ~ 8

Author(s):

J.W.H. Ferguson ◽

M.N. Bester

Keyword(s):

Spatial Autocorrelation ◽

Spatial Data ◽

Senior Author ◽

Line Transect ◽

Data Set ◽

Biological Surveys ◽

Pack Ice ◽

Antarctic Seals ◽

Environmental Measures ◽

The Antarctic

Marked spatial autocorrelation was encountered in an extensive data set on Antarctic seal densities as well as Antarctic pack ice characteristics. Whilst the methodology of measuring spatial autocorrelation is well developed, there is no established infrastructure for statistical inference in terms of correlation analysis or ANOVA. We survey the literature that deals with these problems, as well as some of the approaches that have been proposed for taking autocorrelation into account in inferential statistics. We apply these approaches to a data set comprising Antarctic pack ice seal counts as well as a few environmental measures. In contrast to the predictions from the existing literature, nonlinear estimation suggested that Pearson's r substantially overestimates the true correlation between seal densities and environmental variables. When compared to spatially adjusted analysis of variance, conventional ANOVA that compared seal densities or pack ice characteristics in different areas overestimated the degree of difference between these areas in proportion to the degree of spatial autocorrelation of the particular data set. In our case, the effects of spatial autocorrelation were not neutralised by treating entire transects as single points. These results emphasise the need for a methodology that takes spatial autocorrelation into account for interpreting the spatial data on Antarctic seals collected during the Antarctic pack ice seal (APIS) program. New software written for performing these analyses is available from the senior author.

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The Antarctic Pack Ice

Journal of Glaciology ◽

10.3189/s0022143000008017 ◽

1948 ◽

Vol 1 (4) ◽

pp. 156-173

Author(s):

H. F. P. Herdman

Keyword(s):

Surface Waters ◽

Future Research ◽

Pack Ice ◽

Antarctic Continent ◽

Ice Edge ◽

The Antarctic

AbstractObservations on the distribution and movement of the pack ice around Antarctica. These are based mainly on the work of the “Discovery” Committee’s ships between 1925 and 1939, but also include observations from the pelagic whaling fleet for the years 5930–36. The seasonal advance and retreat of the pack ice are considered in detail and information is given of conditions at the ice edge throughout the year. The movement, or drift, of the pack ice is thought to be closely connected with the surface waters around the Antarctic Continent and a brief account of these currents is included. Some outstanding problems are mentioned in connexion with future research and attention is drawn to the need for air reconnaissance.

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Positive selection on the killer whale mitogenome

Biology Letters ◽

10.1098/rsbl.2010.0638 ◽

2010 ◽

Vol 7 (1) ◽

pp. 116-118 ◽

Cited By ~ 73

Author(s):

Andrew D. Foote ◽

Phillip A. Morin ◽

John W. Durban ◽

Robert L. Pitman ◽

Paul Wade ◽

...

Keyword(s):

Amino Acid ◽

Positive Selection ◽

Killer Whale ◽

Functional Change ◽

Ecological Niches ◽

Physico Chemical ◽

Pack Ice ◽

Metabolic Performance ◽

Property Changes ◽

The Antarctic

Mitochondria produce up to 95 per cent of the eukaryotic cell's energy. The coding genes of the mitochondrial DNA may therefore evolve under selection owing to metabolic requirements. The killer whale, Orcinus orca , is polymorphic, has a global distribution and occupies a range of ecological niches. It is therefore a suitable organism for testing this hypothesis. We compared a global dataset of the complete mitochondrial genomes of 139 individuals for amino acid changes that were associated with radical physico-chemical property changes and were influenced by positive selection. Two such selected non-synonymous amino acid changes were found; one in each of two ecotypes that inhabit the Antarctic pack ice. Both substitutions were associated with changes in local polarity, increased steric constraints and α-helical tendencies that could influence overall metabolic performance, suggesting a functional change.

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