The status and seasonal occurrence of Leopard Seals, Hydrurga leptonyx, in Tasmanian waters.

1994 ◽  
Vol 17 (1) ◽  
pp. 97
Author(s):  
D. Rounsevell ◽  
D. Pemberton
Keyword(s):  
Age Structure ◽  
Seasonal Occurrence ◽  
Clinal Variation ◽  
Dispersal Pattern ◽  
Marine Fauna ◽  
Pack Ice ◽  
Subantarctic Islands ◽  
Hydrurga Leptonyx ◽  
The Status ◽  
The Antarctic

Seventy nine sightings of Leopard Seals, Hydrurga leptonyx, made over a period of 7 years in Tasmania are reported. They show that the species occurs annually in Tasmanian waters between July and November, probably as a result of northward movement from the Antarctic pack ice zone. Its seasonal occurrence in Tasmanian waters implies that it is a regular member of the marine fauna of the region. This is in contrast to previous reports that the species was a rare vagrant, occasionally stranding along the coastline. Comparisons of the age structure of H. leptonyx in Tasmania with those on subantarctic islands suggests that there is a clinal variation with latitude in the dispersal pattern, as young animals disperse further north than adults.

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

2008 ◽  
Vol 20 (2) ◽  
pp. 123-133 ◽  
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).

scholarly journals Summer circumpolar acoustic occurrence and call rates of Ross, Ommatophoca rossii, and leopard, Hydrurga leptonyx, seals in the Southern Ocean

Polar Biology ◽  
2021 ◽  
Vol 44 (2) ◽  
pp. 433-450
Author(s):  
Fannie W. Shabangu ◽  
Tracey L. Rogers
Keyword(s):  
Southern Ocean ◽  
Austral Summer ◽  
Call Rate ◽  
Leopard Seal ◽  
Survey Techniques ◽  
Pack Ice ◽  
Hydrurga Leptonyx ◽  
Spatio Temporal ◽  
The Antarctic ◽  
Temporal Overlap

Abstract Two of the Antarctic pack ice seals, Ross, Ommatophoca rossii, and leopard, Hydrurga leptonyx, seals, are extremely difficult to study via traditional visual survey techniques, yet are ideal for an acoustic survey as they are highly vociferous and produce an array of underwater sounds during the austral summer. To determine their acoustic occurrence in the Antarctic pack ice, we use their calls, detected within 680 acoustic recordings made between 1999 and 2009 as part of two multinational programmes. Siren calls of Ross seals were detected mainly in January, and 9.88 calls per minute from low siren calls was the highest call rate for this species. High numbers of Ross seal calls were detected close to the ice edge in areas between 0° and 20° E and 60° and 130° E, suggesting these are important summer habitats. Leopard seal calls were detected mainly in December and January, and December had the highest percentage of calls. Call rate of 11.93 calls per minute from low double trills was the highest call rate for leopard seals. Leopard seal calls were detected throughout the Southern Ocean with more calls detected throughout the pack ice. There was little spatio-temporal overlap in call occurrence of Ross and leopard seals, but both species were more vocally active during the day. Longitude and latitude were the most important predictors of Ross seal occurrence, and month of the year highly predicted leopard seal occurrence. This is the first study to examine the circumpolar acoustic occurrence of Ross and leopard seals in the Southern Ocean pack ice.

Roman Age Structure: Evidence and Models

2001 ◽  
Vol 91 ◽  
pp. 1-26 ◽  
Author(s):  
Walter Scheidel
Keyword(s):  
Age Structure ◽  
Cultural Practices ◽  
Well Being ◽  
The Elderly ◽  
Public Affairs ◽  
High Fertility ◽  
Average Life Expectancy ◽  
Specific Distribution ◽  
The Status ◽  
To Come

For many Romans, life was short. In consequence, the young greatly outnumbered the elderly. Historians have long accepted these basic truths, even if they are only beginning to come to terms with the social implications of an alien demographic regime. But how short is ‘short’, and how many Romans were children, how many adults? Does it matter, and can we know?The importance of demographic structure is not in doubt. High mortality causes scarce energy resources to be wasted in pregnancies and nursing, and poses a disincentive to investment in education. It destabilizes families and households, exposes orphans and widows to risk and potential hardship, and shortens the time-horizons of economic activity. In the long term, average life expectancy is the principal determinant of fertility. Poor chances of survival trigger high birth rates to ensure genetic survival. High fertility, in turn, is negatively correlated with the status and well-being of women, and constrains female participation in economic and public affairs. Overall age structure, in conjunction with cultural practices from marriage to child care, determines the prevalence of orphans and widows, and affects the age-specific distribution of fertility. In sum, age structure is instrumental in framing and shaping expectations and experiences. For this reason alone, our understanding of life in the Roman world is critically dependent on our knowledge of demographic conditions.

scholarly journals Albedo of the ice covered Weddell and Bellingshausen Seas

2012 ◽  
Vol 6 (2) ◽  
pp. 479-491 ◽  
Author(s):  
A. I. Weiss ◽  
J. C. King ◽  
T. A. Lachlan-Cope ◽  
R. S. Ladkin
Keyword(s):  
Sea Ice ◽  
Surface Albedo ◽  
Austral Summer ◽  
Open Water ◽  
Weddell Sea ◽  
First Year ◽  
Pack Ice ◽  
Bellingshausen Sea ◽  
The Mean ◽  
The Antarctic

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.

On the taxonomy of Apistobranchus species (Polychaeta: Apistobranchidae) from the Antarctic

Zootaxa ◽  
2007 ◽  
Vol 1440 (1) ◽  
pp. 51 ◽  
Author(s):  
MÔNICA A. VARELLA PETTI ◽  
EDMUNDO F. NONATO ◽  
SANDRA BROMBERG ◽  
PAULA F. GHELLER ◽  
PAULO CESAR PAIVA ◽  
...  
Keyword(s):  
Type Material ◽  
Valid Species ◽  
Ecological Studies ◽  
First Report ◽  
Additional Work ◽  
The Status ◽  
The Antarctic

The first report of Apistobranchus Levinsen, 1883 (Family Apistobranchidae) in Antarctica was presented by Hartman (1967). Two species were later described: Apistobranchus glacierae Hartman, 1978 and Apistobranchus gudrunae Hartmann- Schröder & Rosenfeldt, 1988, which differed from A. glacierae mainly by having compound setae. Subsequently, ecological studies in Antarctica have identified both of these species. On the status of Antarctic Apistobranchus, we concluded that there is up to now, only one valid species, A. glacierae. The character ‘compound-setae’ referred for A. gudrunae is in fact simple limbate ones eventually splintered as described for A. glacierae. Other characters, also previously considered as diagnostics for A. gudrunae, did not differ in both species as shown by the observation of several specimens of different sizes and type material of A. glacierae and A. gudrunae. All the reports on the densities of Antarctic apistobranchids, including ours, show that they have higher values in finer sediments of 20 and 40 m depth. The need of additional work, including the rearing of specimens in the laboratory and plankton analysis, is emphasized.

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

2001 ◽  
Vol 13 (2) ◽  
pp. 150-157 ◽  
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.

scholarly journals In situmorphometric survey elucidates the evolutionary systematics of the EurasianHimantoglossumclade (Orchidaceae: Orchidinae)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e2893 ◽  
Author(s):  
Richard M. Bateman ◽  
Attila Molnár V. ◽  
Gábor Sramkó
Keyword(s):  
Molecular Phylogenetics ◽  
Morphological Characters ◽  
Morphometric Character ◽  
Clinal Variation ◽  
Plant Vigour ◽  
Parallel Acquisition ◽  
The Status ◽  
Show Evidence ◽  
Conservation Concern ◽  
Vegetative Characters

Background and AimsThe charismaticHimantoglossum s.l.clade of Eurasian orchids contains an unusually large proportion of taxa that are of controversial circumscriptions and considerable conservation concern. Whereas our previously published study addressed the molecular phylogenetics and phylogeography of every named taxon within the clade, here we use detailed morphometric data obtained from the same populations to compare genotypes with associated phenotypes, in order to better explore taxonomic circumscription and character evolution within the clade.MethodsBetween one and 12 plants found in 25 populations that encompassed the entire distribution of theHimantoglossum s.l.clade were measuredin situfor 51 morphological characters. Results for 45 of those characters were subjected to detailed multivariate and univariate analyses.Key ResultsMultivariate analyses readily separate subgenusBarliaand subgenusComperiafrom subgenusHimantoglossum, and also the early-divergentH. formosumfrom the less divergent remainder of subgenusHimantoglossum. The sequence of divergence of these four lineages is confidently resolved. Our experimental approach to morphometric character analysis demonstrates clearly that phenotypic evolution withinHimantoglossumis unusually multi-dimensional.ConclusionsDegrees of divergence between taxa shown by morphological analyses approximate those previously shown using molecular analyses.Himantoglossum s.l. is readily divisible into three subgenera. The three sections of subgenusHimantoglossum—hircinum,caprinumandformosum—are arrayed from west to east with only limited geographical overlap. At this taxonomic level, their juxtaposition combines with conflict between contrasting datasets to complicate attempts to distinguish between clinal variation and the discontinuities that by definition separatebona fidespecies. All taxa achieve allogamy via food deceit and have only weak pollinator specificity. Artificial crossing demonstrates that intrinsic sterility barriers are weak. Although we have found evidence of gene flow among and within the three sections of subgenusHimantoglossum, reports of natural hybrids are surprisingly rare, probably because putative parents are sufficiently similar to questionably warrant the status of species. Phenological separation and increased xeromorphy characterise the origin of subgenusBarlia. Several individual morphological characters show evidence of parallel acquisition, and loss of features is especially frequent in floral markings among members of sectioncaprinum. Detailed patterns of gain and loss demonstrate that several different categories of flower markings are inherited independently. Along with the dimensions of labellar lobes, these pigmentation characters have been over-emphasised in previous taxonomic treatments. Increased plant vigour was a crucial element of the origin of the genus, but vegetative characters underwent remarkably little subsequent evolution. Attempts to reconstruct hypothetical ancestors at internal nodes of the phylogeny are weakened by (a) uncertain placement ofSteveniellaas sister toHimantoglossum s.l.and (b) uncertain relationships among subtly different putative species within sectioncaprinum. Nonetheless, heterochronic/allometric trends, ultimately limited by functional constraints, clearly dictate transitions between contrasting flower sizes and complex labellum shapes.

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

Polar Record ◽  
1990 ◽  
Vol 26 (159) ◽  
pp. 277-288 ◽  
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.

Developing an Iranian Antarctic Science Roadmap: A Legal and Policy Outlook

2019 ◽  
Vol 10 (1) ◽  
pp. 435-454
Author(s):  
Zia E. Madani ◽  
Julia Jabour
Keyword(s):  
Scientific Research ◽  
Strategic Plan ◽  
Geographical Proximity ◽  
Law And Policy ◽  
Number Of Factors ◽  
The Status ◽  
Antarctic Treaty ◽  
The Antarctic ◽  
Preparatory Work ◽  
Antarctic Treaty System

The Antarctic offers unique opportunities to scientists in many disciplines for improving understanding of regional and global conditions. The governing Antarctic Treaty has 53 State Parties, many of which do not have geographical proximity to the continent. However, the importance of various disciplines of science and many other factors, urge them to participate in the Antarctic scientific activities. Therefore, it is not surprising that Iran is considering participation in Antarctic scientific research, and it has now set processes in motion to join these states in their endeavour to undertake research in Antarctica and contribute to its governance. Iran will develop a strategic plan prior to the commencement of its Antarctic activities, outlining its vision and objectives of an Antarctic program, as well as the financial and logistical implications, and is currently undertaking preparatory work that will culminate in the drafting of an Antarctic strategic plan. In doing so, the authors examined a number of factors including ones that could be identified in Antarctic law and policy as influencing the status and development of the existing Antarctic regime, the recent Antarctic Treaty States’ accession processes and strategies, the express or implied motivations for States to join the Antarctic Treaty, and generally the Antarctic Treaty System, all of which can be reached based on the aforementioned examination that can be incorporated in an Iranian Antarctic science roadmap.

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