Mawson Station Research Articles

USe of morphometric parameters for the determination of sex of Adelie penguins.

The sex of Addie penguins, Pygoscelis adeliae, may be determined by cloacal examination during the early part of the breeding season. Later in the season it becomes increasingly difficult to determine the sex of penguins by this method as the structures used for identification regress. Discriminant analysis of morphometric characters has been suggested as an alternative. This technique was examined for breeding birds of known sex near Mawson Station, Antarctica. The sex of 89% of breeding birds could be correctly determined by comparing the discriminant score D = 0.582 Bl + 1.118 Bd + 0.219Fw, where Bl is bill length, Bd is bill depth and Fw is flipper width, with a mean discriminant score (MDS) of 55.39. In all, the sexes of 87% were correctly determined by means of length and depth only (D=0.601Bl+ 1.154Bd, MDS=44.96). The sex of juvenile birds could not be determined. Determination of sex by discriminant analysis is shown to give acceptable estimates of morphometric characters divided by sex where only the mean and variance of these variables but not the sexual identity of individual birds is required. Where absolute accuracy in sex determination is required, 80% of the birds in our samples would have to be discarded to be 90% confident of the sex of the remainder.

The influence of geomagnetic activity on the upper mesosphere/ lower thermosphere in the auroral zone. I. Vertical winds

A scanning Fabry-Perot spectrometer (FPS), located at Mawson station, Antarctica (67†S, 63°E, invariant latitude 70°S) was used to obtain vertical wind, temperature, and emission intensity measurements from the λ558 nm emission of atomic oxygen. The measured temperature is used to assign an approximate emission height to the observations. A spaced-antenna partial-reflection radar was run concurrently with the FPS from which the presence of enhanced ionization in the D-region could be inferred from the return heights and strengths of the echoes. Large upwards winds of approximately 30 m s −1, at altitudes less than 110 km, appear to be a direct response of the neutral atmosphere to intense auroral events. It is suggested that the observed upwelling is a result of particle heating at heights below the principal emission height. At higher altitudes, vertical winds of a similar magnitude are also measured during geomagnetically disturbed conditions, although here they do not appear to be associated with particular auroral events. In this case it is suggested that upwelling is produced by a combination of Joule and particle heating.

Microorganisms colonizing plants and soil subjected to different degrees of human activity, including petroleum contamination, in the Vestfold hills and MacRobertson Land, Antarctica

The fungal floras of plant communities and mineral soils were determined at locations both close to and away from sites of human activity. Petroleum contaminated soils and discarded wood which occur near Stations were also studied, the former for bacterial as well as fungal colonization. The fungal floras of uncontaminated natural communities comprised relatively few species, Geomyces pannorum, Phoma herbarum and Thelebolus microsporus being the most common, together with Epicoccum nigrum at Mawson. P. herbarum dominated the fungal floras of mosses at Mossell Lake but E. nigrum was also common in Mawson mossbeds. G. pannorum was widespread and colonized a range of different habitats, particularly in the Vestfold Hills. T. microsporus was also widespread particularly at sites frequented by birds and seals. Phialophora fastigiata was common around the Stations, especially Davis Station, in soils including those contaminated with oil and in wood, and is thought to have been introduced with softwood packing crates. A greater range of taxa including Mortierella, Mucor, Penicillium and Cladosporium spp. was recorded from Mawson Station than from other sites, and this was attributed to the effects of human activity. Few fungi but a range of bacteria were isolated from the petroleum contaminated soils. A high percentage of these soils contained bacteria which could utilize hydrocarbons as a sole carbon source. Some of these bacteria showed a strong degradative potential, namely Flavobacterium spp., Corynebacterium spp., Bacillus spp. and an isolate from the family Enterobacteriaceae. One isolate of Corynebacterium and the Enterobacteriaceae isolate were active hydrocarbon degraders at 1°C. Hormoconis resinae, the imperfect state of Amorphotheca resinae was only isolated from oil spill soils and then only from sites of recent spills. Geomyces pannorum and Thelebolus microsporus were less common in oil contaminated soils than in uncontaminated soils.

Radar observations of prevailing winds and waves in the Southern Hemisphere mesosphere and lower thermosphere

HF radar stations (utilizing the spaced-antenna partial-reflection technique) located at Adelaide (35°S, 138°E) and Mawson Station (67°S, 63°E) have observed horizontal mesospheric winds continuously since mid-1984. Observations in the period 1984–87 are compared with the Northern Hemisphere [latitude conjugate] stations of Kyoto (35°N, 136°E) and Poker Flat (65°N, 147°W), and with satellite-derived circulation models. Particular reference is made to the equinoctial changeovers in zonal flow and to the temporal and altitude variations in the planetary wave activity at Mawson and Adelaide.

Australian network of magnetic observatories

Six magnetic observatories are presently operated by the Australian Bureau of Mineral Resources, Geology and Geophysics (BMR), with assistance from various other organizations. Variometer recordings are made of three or more elements of the field at minute intervals, and absolute measurements are made weekly. There are four observatories on the continent (Canberra, Gnangara, Charters Towers, and Learmonth), one on Macquarie Island, and one at Mawson Station in eastern Antarctica (Figure 1). In addition, semiweekly absolute observations of the field (D, H, and F) are made at the other two permanent Australian Antarctic bases (Casey and Davis). A three‐axis fluxgate magnetometer (EDA Electronics, Toronto , Canada) is operated independently by the Upper Atmosphere Physics group at Davis. Monthly mean values, K indices, and information about magnetic disturbances are published monthly in the BMR Geophysical Observatory Report.

A description of the postlarva ofCygnodraco mawsoniWaite, 1916 (Pisces, Bathydraconidae), from the Southern Ocean

Eight postlarvae of Cygnodraco mawsoni Waite, 1916, were collected off the Australian Antarctic Mawson Station in the South Indian Ocean, during the South African SIBEX II expedition. These postlarvae are distinctive by having a long and slender body, projecting lower jaw and bicoloured caudal fin. Their morphology and pigmentation are unlike any known bathydraconid early life history stages.

Fur seals Arctocephalus spp. at Mawson Station, Antarctica, and in the Southern Ocean

Fur seals <i>Arctocephalus</i> spp. at Mawson Station, Antarctica, and in the Southern Ocean

Staphylococcal epidemiology in Antarctica

An investigation of staphylococcal epidemiology was undertaken at an Australian National Antarctic Research Expedition station during 1965-1966. It concerned the carriage of staphylococci by the men and their dogs, and the occurrence of staphylococci in the station environment. The year-long study indicated that coagulase-negative strains survived better in the Antarctic environment than coagulase-positive strains. It was demonstrated that naturally acquired coagulase-positive strains could not maintain colonization on forearm skin under the usual cold exposure experienced at Mawson station, though coagulase-negative skin strains appeared to thrive during the winter. Staphylococcus albus and S. aureus were able to persist in the anterior nares, despite the sometimes lower temperatures recorded in this micro-climate, probably because of the greater humidity and denser populations found there. The majority of the nasal carriers of S. aureus were persistent carriers, only two men in 27 being found to be occasional carriers of nasal strains, which was consistent with the observation that transfer of this pathogen from man to man is not common under Antarctic conditions. Half of the 27 sledge dogs at the station were found to carry coagulase-positive staphylococci but this did not appear to be of pathological significance to their human handlers. The local inanimate environment, including mess hut, sleeping huts and sleeping bags used on expeditions, was searched for contamination by S. aureus but none was detected.

Ice-Fabric Study of the Mawson Region, East Antarctica

Attempts are made to test the relation predicted by Brace (1960) between strain-rates and the ice-fabric patterns obtained at Mawson station, east Antarctica. These orientation fabrics not only are hardly related to the prediction by Brace (1960) or Kamb (1959) but also change easily within a strain grid with 100m diagonals.Stable patterns of two- and three-maximum fabrics are confirmed. The latter is common and stable in the coarse ice at the surface of the ice sheet. It is apparent that the fabric patterns are generally related to the grain-size. The single-maximum fabric always occurs in fine-grained ice, then more maxima are formed in the course of grain growth.It appears that syntectonic-secondary recrystallization is effective in producing the orientation fabrics with two, three and multiple maxima. Also, the maxima always shift away from the pole of foliation as grain-size increases and there are several stable positions of maximum such as 0°, 17°, 23° and 30°. It is expected that further stable angles would occur with coarser crystals as found in temperate glaciers.

Ice-Fabric Study of the Mawson Region, East Antarctica

Attempts are made to test the relation predicted by Brace (1960) between strain-rates and the ice-fabric patterns obtained at Mawson station, east Antarctica. These orientation fabrics not only are hardly related to the prediction by Brace (1960) or Kamb (1959) but also change easily within a strain grid with 100m diagonals.Stable patterns of two- and three-maximum fabrics are confirmed. The latter is common and stable in the coarse ice at the surface of the ice sheet. It is apparent that the fabric patterns are generally related to the grain-size. The single-maximum fabric always occurs in fine-grained ice, then more maxima are formed in the course of grain growth.It appears that syntectonic-secondary recrystallization is effective in producing the orientation fabrics with two, three and multiple maxima. Also, the maxima always shift away from the pole of foliation as grain-size increases and there are several stable positions of maximum such as 0°, 17°, 23° and 30°. It is expected that further stable angles would occur with coarser crystals as found in temperate glaciers.

TWO VOYAGES TO ANTARCTICA WITH THE AUSTRALIAN NATIONAL ANTARCTIC RESEARCH EXPEDITIONS 1961 AND 1962

On December 22nd, 1961, the writer again sailed with the Australian National Antarctic Research Expedition in the polar vessel Thala Dan, primarily to make a hydrographic survey at Wilkes station during the change-over of personnel. Mr. S. L. Kirkby, licensed surveyor, was also included in the expedition to assist with hydrographic work and to obtain astro-fixes where required. He was in the veteran class, having wintered over at Mawson station in 1956 and 1960.

TWO VOYAGES TO ANTARCTICA WITH THE AUSTRALIAN NATIONAL ANTARCTIC RESEARCH EXPEDITIONS 1961 AND 1962

On December 22nd, 1961, the writer again sailed with the Australian National Antarctic Research Expedition in the polar vessel Thala Dan, primarily to make a hydrographic survey at Wilkes station during the change-over of personnel. Mr. S. L. Kirkby, licensed surveyor, was also included in the expedition to assist with hydrographic work and to obtain astro-fixes where required. He was in the veteran class, having wintered over at Mawson station in 1956 and 1960.