Publications

TitleAbstractYear
Filter
PMID
Filter
death of a leopard seal in the falkland islands. 200212448498
age-related differences in the acoustic characteristics of male leopard seals, hydrurga leptonyx.during the breeding season, the underwater vocalizations and calling rates of adult male leopard seals are highly stereotyped. in contrast, sub-adult males have more variable acoustic behavior. although adult males produce only five stereotyped broadcast calls as part of their long-range underwater breeding displays the sub-adults have a greater repertoire including the adult-like broadcast calls, as well as variants of these. whether this extended repertoire has a social function is unknown due ...200717614516
diet and phylogeny shape the gut microbiota of antarctic seals: a comparison of wild and captive animals.the gut microbiota of mammals underpins the metabolic capacity and health of the host. our understanding of what influences the composition of this community has been limited primarily to evidence from captive and terrestrial mammals. therefore, the gut microbiota of southern elephant seals, mirounga leonina, and leopard seals, hydrurga leptonyx, inhabiting antarctica were compared with captive leopard seals. each seal exhibited a gut microbiota dominated by four phyla: firmicutes (41.5 ± 4.0%), ...201323145888
density can be misleading for low-density species: benefits of passive acoustic monitoring.climate-induced changes may be more substantial within the marine environment, where following ecological change is logistically difficult, and typically expensive. as marine animals tend to produce stereotyped, long-range signals, they are ideal for repeatable surveying. in this study we illustrate the potential for calling rates to be used as a tool for determining habitat quality by using an antarctic pack-ice seal, the leopard seal, as a model.with an understanding of the vocal behavior of a ...201323326339
major histocompatibility complex class ii doa sequences from three antarctic seal species verify stabilizing selection on the do locus.to provide additional support for the sequence conservation and hence the regulatory role of the mhc class ii doa locus, we obtained the nucleotide sequences of exon 2 and exon 3, along with the intervening intron, of the ross seal, and sequences from the exon 2 region from the weddell and leopard seals. these are the first reports of the sequences of this locus from a carnivore species. the results demonstrate strong conservation among mammals for the exon sequence and produce a gene genealogy ...200212542748
antarctophthirus carlinii (anoplura: echinophthiriidae), a new species from the weddell seal leptonychotes weddelli.as a part of an ongoing long-term study on the biology of pack-ice seals in antarctica, we had the opportunity to collect lice from weddell seals (leptonychotes weddelli). we did not find the original description of this host-parasite association. antarctophthirus ogmorhini had previously been reported as a parasite for the weddell seal, but the information is, to a certain extent, confusing. during the development of the present study, we had access to literature concerning the presence of a. o ...201425082018
activity time budget during foraging trips of emperor penguins.we developed an automated method using depth and one axis of body acceleration data recorded by animal-borne data loggers to identify activities of penguins over long-term deployments. using this technique, we evaluated the activity time budget of emperor penguins (n = 10) both in water and on sea ice during foraging trips in chick-rearing season. during the foraging trips, emperor penguins alternated dive bouts (4.8 ± 4.5 h) and rest periods on sea ice (2.5 ± 2.3 h). after recorder deployment a ...201223185608
pathological findings of a fatal leopard seal attack.a unique case of a fatal leopard seal attack against an adult human female is presented. the death occurred in rothera, antarctica when the female was snorkeling while undertaking scientific research. the principle injuries occurred, during life, to the facial areas prior to the act of drowning. the method of attack of leopard seals against their natural prey is discussed and related to the findings on the deceased.200725868891
comparative studies of 'bile salts'. 13. bile acids of the leopard seal, hydrurga leptonyx, and of two snakes of the genus bitis. 196113712142
industrial contaminants in antarctic biota.a critical review of the levels and patterns of industrial contaminants in biota from antarctica and the southern ocean revealed that concentrations are low with respect to other regions of the world, although in some specimens/species (e.g. leopard seal, some invertebrates) they are occasionally high and comparable to those found in regions with a strong human impact; the highest levels of persistent organic pollutants (pops) were detected in the vicinity of scientific stations. bioconcentratio ...200918723171
isolation of an actinomycete from a sea leopard (hydrurga leptonyx). 1977275688
histology of selected tissues of the leopard seal and implications for functional adaptations to an aquatic lifestyle.the microscopic anatomy of the cardio-respiratory system, digestive system, kidney, lymphatic system and integument was investigated in the leopard seal, hydrurga leptonyx, by examining histological sections of tissues collected from leopard seals in antarctica and new south wales, australia. the majority of the tissues had similar histological features to those described in terrestrial mammals and other pinniped species, particularly phocid seals. differences noted included readily identifiable ...200616879598
top-down and bottom-up influences on demographic rates of antarctic fur seals arctocephalus gazella.two major drivers in population dynamics are bottom-up processes, such as environmental factors that affect foraging success, and the top-down impacts of predation. many populations of marine mammal and seabird species appear to be declining in response to reductions in prey associated with the bottom-up effects of climate change. however, predation, which usually occurs at sea and is difficult to observe, may also play a key role. we analysed drivers of population dynamics of antarctic fur seal ...201323444975
distribution and coassociations of selected metals in seals of the antarctic.zinc, cu, cd, pb, ag, ni, co, cr, fe and mn concentrations in some tissues of crabeater seal (lobodon carcinophagus), leopard seal (hydrurga leptonyx) and weddell seal (leptonychotes weddelli) from the antarctic were determined. distinct inter-tissue differences in metal concentrations in seals were observed; liver contained maximum levels of zn, cu, ag and mn, whilst kidney showed the highest levels of cd, ni and co. muscle was characterized by low concentrations of all the elements analyzed. t ...199415091740
immobilisation of southern elephant seals and leopard seals with cyclohexamine anaesthetics and xylazine.ketamine and xylazine were given to 55 southern elephant seals (mirounga leonina) for stomach lavaging, and to three leopard seals (hydrurga leptonyx). the elephant seals showed prolonged apnoea and two of them died owing to aspiration of stomach contents. two of the leopard seals died from unknown causes. tiletamine and zolazepam were given to five elephant seals and one leopard seal. two of the elephant seals and the leopard seal died from unknown causes. xylazine alone was administered to 34 ...19911750175
ketamine hcl and diazepam anaesthesia of a leopard seal (hydrurga leptonyx) for the biopsy of multiple fibromatous epulis. 19846517782
trace element analysis in the serum and hair of antarctic leopard seal, hydrurga leptonyx, and weddell seal, leptonychotes weddellii.leopard seal, hydrurga leptonyx, and weddell seal, leptonychotes weddellii, occupy an upper trophic level within the antarctic ecosystem and are useful indicator species in the southern ocean of trace element concentrations. reference values for the concentration of 19 trace elements were determined in the serum and hair of leopard and weddell seals sampled in eastern antarctica. these reference values can be used as 'baseline' levels for monitoring trace element concentrations in these species. ...200818486190
ancient whales did not filter feed with their teeth.the origin of baleen whales (mysticeti), the largest animals on earth, is closely tied to their signature filter-feeding strategy. unlike their modern relatives, archaic whales possessed a well-developed, heterodont adult dentition. how these teeth were used, and what role their function and subsequent loss played in the emergence of filter feeding, is an enduring mystery. in particular, it has been suggested that elaborate tooth crowns may have enabled stem mysticetes to filter with their postc ...201728855416
source levels of the underwater calls of a male leopard seal.leopard seals (hydrurga leptonyx) are top predators in the antarctic ecosystem. they produce stereotyped calls as part of a stylized underwater vocal display. understanding of their acoustic behavior is improved by identifying the amplitude of their calls. the amplitude of five types of calls (n = 50) from a single male seal were measured as broadband source levels and ranged from 153 to 177 db re 1 μpa at 1 m. the mean source levels differed between call types, the lower frequency calls (l, d, ...201425324053
a bizarre new toothed mysticete (cetacea) from australia and the early evolution of baleen whales.extant baleen whales (cetacea, mysticeti) are all large filter-feeding marine mammals that lack teeth as adults, instead possessing baleen, and feed on small marine animals in bulk. the early evolution of these superlative mammals, and their unique feeding method, has hitherto remained enigmatic. here, i report a new toothed mysticete from the late oligocene of australia that is more archaic than any previously described. unlike all other mysticetes, this new whale was small, had enormous eyes a ...200617015308
leopard seal diets in a rapidly warming polar region vary by year, season, sex, and body size.resolving the preferred prey items and dietary proportions of leopard seals is central to understanding food-web dynamics in the rapidly-warming antarctic peninsula region. previous studies have identified a wide range of prey items; however, due to anecdotal or otherwise limited information, leopard seal diets remain unresolved by seal sex, individual, body size, region, and season. over the 2013, 2014, and 2017 field seasons we collected scat, tissue samples (red blood cells and plasma; n = 23 ...202032493329
a review of heavy metal and organochlorine levels in marine mammals in australia.study of toxic contaminants in marine mammal specimens collected around australia is currently uncoordinated and piecemeal. most states collect samples but there is little or no financial support for their analysis. this study combines data, published or unpublished, from 13 sources. heavy metals have been analysed in about 676 specimens; over 400 were for mercury levels in p. macrocephalus taken at a whaling station. the remaining samples were mostly from toothed whales, a few baleen whales (< ...19947973602
toneburst-evoked auditory brainstem response in a leopard seal, hydrurga leptonyx.toneburst-evoked auditory brainstem responses (abrs) were recorded in a captive subadult male leopard seal. three frequencies from 1 to 4 khz were tested at sound levels from 68 to 122 db peak equivalent sound pressure level (pespl). results illustrate brainstem activity within the 1-4 khz range, with better hearing sensitivity at 4 khz. as is seen in human abr, only wave v is reliably identified at the lower stimulus intensities. wave v is present down to levels of 82 db pespl in the right ear ...201121303028
comparative pathology of nocardiosis in marine mammals.nocardia spp. infections in mammals cause pyogranulomatous lesions in a variety of organs, most typically the lung. members of the nocardia asteroides complex are the most frequently recognized pathogens. nine cases of nocardiosis in free-ranging pinnipeds and 10 cases of nocardiosis in cetaceans were evaluated. host species included the hooded seal (cystophora cristata, n = 8), leopard seal (hydrurga leptonyx, n = 1), atlantic bottlenose dolphin (tursiops truncatus, n = 4), beluga whale (delphi ...200919261643
calling underwater is a costly signal: size-related differences in the call rates of antarctic leopard seals.it is proposed that where sexually selected vocal communication is an honest signal, the call production rate is predicted to change throughout the breeding season. male leopard seals call underwater for many hours each day over their three- to four-month breeding season, and it is hypothesized that a decrease in calling rate would be associated with the declining body condition of smaller males. the calling rates of leopard seals were measured (n = 49 recordings) and compared between seals of d ...201729492003
long term movements and activity patterns of an antarctic marine apex predator: the leopard seal.leopard seals are an important antarctic apex predator that can affect marine ecosystems through local predation. here we report on the successful use of micro geolocation logging sensor tags to track the movements, and activity, of four leopard seals for trips of between 142-446 days including one individual in two separate years. whilst the sample size is small the results represent an advance in our limited knowledge of leopard seals. we show the longest periods of tracking of leopard seals' ...201829870541
an accurate and adaptable photogrammetric approach for estimating the mass and body condition of pinnipeds using an unmanned aerial system.measurements of body size and mass are fundamental to pinniped population management and research. manual measurements tend to be accurate but are invasive and logistically challenging to obtain. ground-based photogrammetric techniques are less invasive, but inherent limitations make them impractical for many field applications. the recent proliferation of unmanned aerial systems (uas) in wildlife monitoring has provided a promising new platform for the photogrammetry of free-ranging pinnipeds. ...201729186134
mercury and major essential elements in seals, penguins, and other representative fauna of the antarctic.concentrations of total hg and major essential elements, ca, mg, na, and k, were measured in the muscle, liver, and kidney of three species of seals, crabeater seal (lobodon carcinophagus), leopard seal (hydrurga leptonyx), and weddell seal (leptonychotes weddelli) collected in the antarctic. the muscle and liver of three species of penguins, i.e., gentoo penguin (pygoscelis papua), adelie penguin (p. adeliae), chinstrap penguin (p. antarctica), and other representative fauna were also analyzed ...19938239712
a molecular view of pinniped relationships with particular emphasis on the true seals.phylogenetic analysis of conservative nucleotide substitutions in 18 complete sequences of the mitochondrial cytochrome b gene of phocidae (true seals), odobenidae (walruses), and otariidae (sea lions and fur seals), plus three ursid and three felid sequences, identified the pinnipeds as monophyletic with otariidae and odobenidae on a common evolutionary branch. analysis of total nucleotide differences separated the evolutionary lineages of northern and southern phocids. both lineages are distin ...19957714914
some anatomical aspects of the cardiovascular system of antarctic seals and their possible functional significance in diving.the hearts and ascending aortae of 11 weddell seals, leptonychotes weddelli, three adult crabeater seals, lobodon carcinophagus, two adult ross seals, ommatophoca rossi, and one adult leopard seal, hydrurga leptonyx, were examined for comparison with terrestrial forms. the weddell seal specimens were from animals ranging in age from midterm in fetal development to mature adults. all specimens were collected in 1971, 1972, and 1973, from mcmurdo sound and the ross sea, antarctica. the phocid hear ...19751111424
do free-ranging common brushtail possums (trichosurus vulpecula) play a role in the transmission of toxoplasma gondii within a zoo environment?to investigate the possible role of common brushtail possums (trichosurus vulpecula) in the transmission of toxoplasma gondii within a zoo environment, a serological survey of a free-ranging population resident within taronga zoo, sydney, australia was undertaken using the modified agglutination test (mat). for comparison, the seroprevalence of t. gondii antibodies was also assessed in a possum population inhabiting a felid-free, non-urban woodland habitat. six of 126 possums (4.8%) from the zoo ...200818281157
growth in pinnipeds.this review presents summary figures of, and fits growth curves to, data on body lengths (as standard length, sl, whenever possible) of pinnipeds at ages estimated to o.i y. (1) generalized von bertalanffy (vb) growth curves are fitted to most data: lx = l infinity (i - ea(x-x0)b, lx is length at age x, x0 is the origin of the curve (here chosen a priori as time of initiation of embryonic growth), l infinity is asymptotic length, a (which is negative) determines rate of approach to the asymptote ...19938457634
new zealand's cetaceans and pinnipeds.the 8 species of baleen whale in new zealand waters range in length from 6 to 30+ metres, and the 25 species of toothed whale range up to 18 metres. a single porpoise species is known in new zealand sub-antarctic waters. the baleen whales and many of the toothed whales are migratory, and new zealand straddles their well-defined routes: a combination which allowed whaling to flourish. the toothed whales are the more gregarious and may indulge in mass strandings. current research aims to investiga ...198116030799
a new approach to the solution of the linear mixing model for a single isotope: application to the case of an opportunistic predator.mixing models are used to determine diets where the number of prey items are greater than one, however, the limitation of the linear mixing method is the lack of a unique solution when the number of potential sources is greater than the number (n) of isotopic signatures +1. using the isosource program all possible combinations of each source contribution (0-100%) in preselected small increments can be examined and a range of values produced for each sample analysed. we propose the use of a moore ...200415599768
the influence of sea ice, wind speed and marine mammals on southern ocean ambient sound.this paper describes the natural variability of ambient sound in the southern ocean, an acoustically pristine marine mammal habitat. over a 3-year period, two autonomous recorders were moored along the greenwich meridian to collect underwater passive acoustic data. ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. with increasing sea-ice concentration, area and thickness, sound levels ...201728280544
serum proteins in the leopard seal, hydrurga leptonyx, in prydz bay, eastern antarctica and the coast of nsw, australia.blood protein analysis including total serum protein and albumin by chemical methods, fibrinogen estimation and serum protein electrophoresis (spe) was performed on the leopard seal, hydrurga leptonyx. the most commonly observed spe pattern was eight fractions designated albumin, alpha(1a), alpha(1b), alpha(2a), alpha(2b), beta(1), beta(2) and gamma-globulin. significantly higher total serum protein and albumin concentrations, as determined by chemical methods, and significantly higher alpha(2)- ...200515993637
the better to eat you with: the comparative feeding morphology of phocid seals (pinnipedia, phocidae).one adaptation crucial to the survival of mammalian lineages that secondarily transitioned from land to water environments was the ability to capture and consume prey underwater. phocid seals have evolved diverse feeding strategies to feed in the marine environment, and the objectives of this study were to document the specialized feeding morphologies and identify feeding strategies used by extant phocids. this study used principal component analysis (pca) to determine the major axes of diversif ...201626646351
Displaying items 1 - 37 of 37