| thyroid morphology and function and its role in thermoregulation in the newborn southern elephant seal (mirounga leonina) at macquarie island. | the thyroid gland of the newborn southern elephant seal pup exhibits markedly increased secretory activity during the first 24 hours after birth. thyroid epithelial cell height is cuboidal to columnar for pups from birth to 48 hours postpartum after which it decreases by five days of age. ultrastructurally the thyroid epithelial cells show pseudopodia protruding into the lumen at zero, two and six hours after birth. after 24 hours postpartum pseudopodia are rarely observed in thyroid follicles f ... | 1991 | 1917675 |
| use of a tiletamine-zolazepam mixture to immobilise wild grey seals and southern elephant seals. | a mixture of tiletamine and zolazepam at a combined dose of 1 mg/kg was a reliable and safe agent for immobilising wild grey seals (halichoerus grypus) and southern elephant seals (mirouga leonina). the agent had a number of advantages over all the other agents used previously. | 1990 | 2309387 |
| the use of a ketamine-diazepam mixture to immobilise wild grey seals (halichoerus grypus) and southern elephant seals (mirounga leonina). | a mixture of ketamine and diazepam, at doses of 6 mg/kg and 0.30 mg/kg respectively, proved to be a reliable and reasonably safe immobilisation agent for field work on grey and southern elephant seals. it was better than previously reported drugs used either singly or in combination. | 1988 | 3195003 |
| molecular population genetics of the southern elephant seal mirounga leonina. | southern elephant seals breed on sub-antarctic islands and have a circumpolar distribution. we assayed mitochondrial dna (mtdna) and nuclear dna (ndna) variation in the three main populations in the south atlantic, south indian, and south pacific oceans, and a smaller continental population in south america. population structure of mtdna was strong and not consistent with isolation by distance. the ndna loci, although less informative, were consistent with the mtdna results. geographic structure ... | 1998 | 9691049 |
| pharmacokinetics of intravenously administered ketamine in southern elephant seals (mirounga leonina). | southern elephant seals (mirounga leonina) are large, potentially dangerous animals which must be restrained before study or treatment. however, chemical restraint is unpredictable, possibly because of differences in body composition during fasting ashore, and circulatory adaptations to enable diving. the pharmacokinetics of ketamine (1.1 mg/kg i.v.) was studied in 15 southern elephant seals which had come ashore on macquarie island. the animals were first sedated with pethidine (5 mg/kg i.m.) t ... | 1999 | 10530900 |
| arbovirus of marine mammals: a new alphavirus isolated from the elephant seal louse, lepidophthirus macrorhini. | a novel alphavirus was isolated from the louse lepidophthirus macrorhini, collected from southern elephant seals, mirounga leonina, on macquarie island, australia. the virus displayed classic alphavirus ultrastructure and appeared to be serologically different from known australasian alphaviruses. nearly all macquarie island elephant seals tested had neutralizing antibodies against the virus, but no virus-associated pathology has been identified. antarctic division personnel who have worked exte ... | 2001 | 11287559 |
| evolutionary relationships and systematics of the alphaviruses. | partial e1 envelope glycoprotein gene sequences and complete structural polyprotein sequences were used to compare divergence and construct phylogenetic trees for the genus alphavirus. tree topologies indicated that the mosquito-borne alphaviruses could have arisen in either the old or the new world, with at least two transoceanic introductions to account for their current distribution. the time frame for alphavirus diversification could not be estimated because maximum-likelihood analyses indic ... | 2001 | 11581380 |
| evidence of helicobacter sp. in dental plaque of captive dolphins (tursiops gephyreus). | gastrointestinal lesions have been extensively reported in wild and captive marine mammals. however, their etiology remains unclear. in humans and other animals, chronic gastritis and peptic ulcers have been associated with helicobacter sp. therefore, the aim of our study was to investigate the presence of helicobacter sp. in the gastric juice, dental plaque, and saliva of marine mammals living in a controlled environment. five dolphins (tursiops gephyreus), one killer whale (orcinus orca), one ... | 2002 | 12238390 |
| genetic evidence for two sibling species within contracaecum ogmorhini johnston & mawson, 1941 (nematoda: anisakidae) from otariid seals of boreal and austral regions. | genetic variation of contracaecum ogmorhini (sensu lato) populations from different otariid seals of the northern and southern hemisphere was studied on the basis of 18 enzyme loci as well as preliminary sequence analysis of the mitochondrial cyt b gene (260 bp). samples were collected from zalophus californianus in the boreal region and from arctocephalus pusillus pusillus, a. pusillus doriferus and a. australis from the austral region. marked genetic heterogeneity was found between c. ogmorhin ... | 2003 | 12567006 |
| climate change and seal survival: evidence for environmentally mediated changes in elephant seal, mirounga leonina, pup survival. | maternal and physical factors play a significant role in animal life-history variability, which means that large scale climate change has the potential to affect the size and dynamics of animal populations indirectly through maternal investment and directly through conditions that animals are exposed to. however, little is known about the effects of large-scale oceanographic events such as the el-niño southern oscillation (enso) that influence productivity in the southern ocean and the abundance ... | 2005 | 16024347 |
| handling intensity and the short- and long-term survival of elephant seals: addressing and quantifying research effects on wild animals. | this study addresses the consequences of repeated human handling on the survival of an endangered phocid, the southern elephant seal and the implications for wildlife research. southern elephant seal pups were repeatedly handled during the first six weeks of their lives. the possibility that such anthropogenic research may have altered the very parameters that were being investigated is a topical and relevant study area that we address here. our results show that there were no measurable effects ... | 2005 | 16201211 |
| lactational transfer of pcbs and chlorinated pesticides in pups of southern elephant seals (mirounga leonina) from antarctica. | seven pairs of southern elephant seals (mirounga leonina) pups and their dams were sampled during the late weaning season among a breeding population of seals on elephant island in antarctica. the blubber of the pups and the milk and blubber of their dams were analyzed for lipid-normalized concentrations of pcbs and organochlorines compounds in order to evaluate the lactational transfer of these contaminants. the lipid-normalized concentrations in these tissues were in the ppb range (i.e., ngg(- ... | 2009 | 19201445 |
| ddt in endangered galapagos sea lions (zalophus wollebaeki). | we characterize for the first time the presence of ddt and its metabolites in tropical galapagos sea lions (zalophus wolleabeki). ?ddt concentrations in galapagos sea lion pups sampled in 2005 and 2008 ranged from 16 to 3070 µg/kg lipid. concentrations of ?ddt in pups in 2008 averaged 525 µg/kg lipid and were 1.9 times higher than that (281 µg/kg lipid) detected in pups in 2005. these concentrations are lower than those reported in many pinnipeds elsewhere, comparable to those in hawaiian monk s ... | 2011 | 21353257 |
| Indications for both host-specific and introduced genotypes of Staphylococcus aureus in marine mammals. | Staphylococcus aureus is present in the marine environment and causes disease in marine mammals. To determine whether marine mammals are colonized by host-specific strains or by strains originating from other species, we performed multi-locus sequence typing on ten S. aureus strains isolated from marine mammals in the U.K., the Netherlands, and the Antarctic. Four new sequence types of S. aureus were discovered. S. aureus strains from a southern elephant seal (n=1) and harbour porpoises (n=2) di ... | 2011 | 22112853 |
| n-terminal amino acid sequence of trypsinogen from the elephant seal mirounga leonina l. (carnivora). | | 2015 | 4834682 |
| prolonged and multiple immobilizations of the southern elephant seal using ketamine hydrochloride-xylazine hydrochloride or ketamine hydrochloride-diazepam combinations. | thirty seven southern elephant seals (mirounga leonina) were singularly or repeatedly immobilized with combinations of ketamine hydrochloride (hcl) and xylazine hcl or ketamine hcl and diazepam. atropine sulphate was included in the drug combinations. to permit experimental procedures the seals were immobilized for periods of 30-330 min. the mean induction dose of ketamine hcl was 8.71 +/- 0.25 mg/kg (mean +/- se). the mean induction time was 16.02 +/- 2.62 min. for the elephant seals immobilize ... | 2013 | 3682087 |
| molecular systematics of pinniped hookworms (nematoda: uncinaria): species delimitation, host associations and host-induced morphometric variation. | hookworms of the genus uncinaria have been widely reported from juvenile pinnipeds, however investigations of their systematics has been limited, with only two species described, uncinaria lucasi from northern fur seals (callorhinus ursinus) and uncinaria hamiltoni from south american sea lions (otaria flavescens). hookworms were sampled from these hosts and seven additional species including steller sea lions (eumetopias jubatus), california sea lions (zalophus californianus), south american fu ... | 2013 | 24162075 |
| morphometric and molecular characterization of the species of uncinaria frölich, 1789 (nematoda) parasitic in the australian fur seal arctocephalus pusillus doriferus (schreber), with notes on hookworms in three other pinniped hosts. | this study presents morphological and molecular data on hookworms from the australian fur seal arctocephalus pusillus doriferus (schreber) currently identified in australian waters as uncinaria hamiltoni baylis, 1933. additional specimens from the australian sea lion neophoca cinerea (péron) and the new zealand fur seal arctocephalus forsteri (lesson) from australia, and the southern elephant seal mirounga leonina (linnaeus) from antarctica, were included. using the internal transcribed spacer ( ... | 2013 | 23595493 |
| rapid response of a marine mammal species to holocene climate and habitat change. | environmental change drives demographic and evolutionary processes that determine diversity within and among species. tracking these processes during periods of change reveals mechanisms for the establishment of populations and provides predictive data on response to potential future impacts, including those caused by anthropogenic climate change. here we show how a highly mobile marine species responded to the gain and loss of new breeding habitat. southern elephant seal, mirounga leonina, rema ... | 2009 | 19593366 |
| persistent organic pollutants and stable isotopes in pinnipeds from king george island, antarctica. | in the present work, fat, skin, liver and muscle samples from leptonychotes weddellii (weddell seal, n=2 individuals), lobodon carcinophagus (crabeater seal, n=2), arctocephalus gazella (antarctic fur seal, n=3) and mirounga leonina (southern elephant seal, n=1) were collected from king george island, antarctica, and analysed for pops (pcbs, organochlorine pesticides and pbdes) and stable isotopes (δ¹³c and δ¹⁵n in all tissues but fat). pbdes could be found in only one sample (l. weddellii fat). ... | 2012 | 23154138 |
| relative abundance and behavior of marine mammals exposed to transmissions from the heard island feasibility test. | the heard island feasibility test source transmitted a hum at 209-220 db re: 1 micropa at 175-m depth, centered on 57 hz with a maximum bandwidth of 30 hz for 1 h of every 3. experienced marine mammal observers conducted line-transect surveys and monitored marine mammal behavior visually and acoustically in a 70 x 70 km square centered on the transmission site. thirty-nine groups of cetaceans and 19 of pinnipeds were sighted from both vessels before the start of transmissions. thirty-nine groups ... | 1994 | 7963037 |
| southern ocean frontal structure and sea-ice formation rates revealed by elephant seals. | polar regions are particularly sensitive to climate change, with the potential for significant feedbacks between ocean circulation, sea ice, and the ocean carbon cycle. however, the difficulty in obtaining in situ data means that our ability to detect and interpret change is very limited, especially in the southern ocean, where the ocean beneath the sea ice remains almost entirely unobserved and the rate of sea-ice formation is poorly known. here, we show that southern elephant seals (mirounga l ... | 2008 | 18695241 |
| a phylogenomic study of the genus alphavirus employing whole genome comparison. | the phylogenetics of the genus alphavirus have historically been characterized using partial gene, single gene or partial proteomic data. we have mined cdna and amino acid sequences from genbank for all fully sequenced and some partially sequenced alphaviruses and generated phylogenomic analyses of the genus alphavirus genus, employing capsid encoding structural regions, non-structural coding regions and complete viral genomes. our studies support the presence of the previously reported recombin ... | 2005 | 18629194 |
| residues of persistent organochlorine contaminants in southern elephant seals (mirounga leonina) from elephant island, antarctica. | contamination of blubber tissues by organochlorine pesticides (oc) and pcbs was assessed in female and male pups and juveniles, as well as in adult females and subdominant adult males of the southern elephant seal, mirounga leonina, from elephant island in the antarctic peninsula. all residues of persistent organochlorine contaminants analyzed were found in blubber samples, except for beta-hch, endosulfan ii, endrin, heptachlor, and aldrin. the relative concentrations of the analytes detected we ... | 2007 | 17612156 |
| successful foraging zones of southern elephant seals from the kerguelen islands in relation to oceanographic conditions. | southern elephant seals, mirounga leonina, undertake large-scale oceanic movements to access favourable foraging areas. successful foraging areas of elephant seals from the kerguelen islands are investigated here in relation to oceanographic parameters. movements and diving activity of the seals as well as oceanographic data were collected through a new generation of satellite relayed devices measuring and transmitting locations, pressure, temperature and salinity. for the first time, we have as ... | 2007 | 17472917 |
| detection and characterization of a cryptosporidium isolate from a southern elephant seal (mirounga leonina) from the antarctic peninsula. | the presence of cryptosporidium and giardia in 221 fecal samples from different species of antarctic pinnipeds was investigated by immunofluorescence microscopy and pcr. cryptosporidium, a skunk-like genotype, was detected only in a southern elephant seal. giardia was not detected. this is the first report of a cryptosporidium sp. in antarctic marine mammals. | 2011 | 21169427 |
| holocene elephant seal distribution implies warmer-than-present climate in the ross sea. | we show that southern elephant seal (mirounga leonina) colonies existed proximate to the ross ice shelf during the holocene, well south of their core sub-antarctic breeding and molting grounds. we propose that this was due to warming (including a previously unrecognized period from approximately 1,100 to 2,300 (14)c yr b.p.) that decreased coastal sea ice and allowed penetration of warmer-than-present climate conditions into the ross embayment. if, as proposed in the literature, the ice shelf su ... | 2006 | 16801535 |
| how to build a deep diver: the extreme morphology of mesoplodonts. | mesoplodont beaked whales are extreme divers, diving for over 45 mins and to depths of over 800 m. these dives are of similar depth and duration to those of the giant sperm whale (physeter macrocephalus) whose body mass can be 50 times larger. velten et al. (2013) provided anatomical data that demonstrated that on-board oxygen stores were sufficient to aerobically support the extreme dives of mesoplodonts if their diving metabolic rates are low. because no physiological data yet exist, we utiliz ... | 2016 | 27940620 |
| corynosoma australe johnston, 1937 and c. cetaceum johnston & best, 1942 (acanthocephala: polymorphidae) from marine mammals and fishes in argentinian waters: allozyme markers and taxonomic status. | genetic and morphological studies were carried out on acanthocephalans belonging to corynosoma lühe, 1904 and referable to the species c. cetaceum johnston & best, 1942 and c. australe johnston, 1937, which were recovered from both definitive and intermediate hosts in argentinian waters. the aims were to estimate the level of genetic differentiation between the two taxa at any stage of their life-cycle, to provide genetic (allozyme) markers for their recognition and to analyse the systematic sta ... | 2005 | 15980967 |
| conservation of mhc class ii doa sequences among carnivores. | we obtained the nucleotide sequence for most of the major histocompatibility complex (mhc) class ii doa locus for weddell, leopard, northern elephant, and southern elephant seals and from the coyote and compared them to all known doa data available to date. we found generally low levels of interspecific polymorphisms, providing further support for stabilizing selection acting on the doa locus. this suggests that do gene products play a substantial functional role in the regulation of antigen pre ... | 2005 | 15730524 |
| jeotgalicoccus pinnipedialis sp. nov., from a southern elephant seal (mirounga leonina). | a previously unknown gram-positive, catalase-positive, facultatively anaerobic, non-spore-forming, coccus-shaped bacterium (a/g14/99/10(t)), originating from the mouth of a female southern elephant seal, was subjected to a taxonomic analysis. comparative 16s rrna gene-sequencing showed that the organism formed a hitherto unknown subline within the catalase-positive, low-g+c, gram-positive cocci, exhibiting a specific association with species of the genus jeotgalicoccus. sequence divergence value ... | 2004 | 15143018 |
| increasing levels and biomagnification of persistent organic pollutants (pops) in antarctic biota. | representatives of the antarctic food web (krill, cephalopod, fish, penguin, seal) of the area around elephant island and from the weddell sea were analysed for the most recalcitrant organochlorine compounds. due to sorption of the compounds to sinking particles and accumulation in sediments, two benthic fish species (gobionotothen gibberifrons, chaenocephalus aceratus) feeding on benthos invertebrates and fish reflected significantly increasing concentrations within a decade (1987-1996), while ... | 2004 | 14972581 |
| blubber and buoyancy: monitoring the body condition of free-ranging seals using simple dive characteristics. | elephant seals regularly perform dives during which they spend a large proportion of time drifting passively through the water column. the rate of vertical change in depth during these "drift" dives is largely a result of the proportion of lipid tissue in the body, with fatter seals having higher (more positive or less negative) drift rates compared with leaner seals. we examined the temporal changes in drift rates of 24 newly weaned southern elephant seal (mirounga leonina) pups during their fi ... | 2003 | 12939372 |
| you are what you eat: describing the foraging ecology of southern elephant seals (mirounga leonina) using blubber fatty acids. | understanding the trophodynamics of marine ecosystems requires data on the temporal and spatial variation in predator diet but, particularly for wide-ranging species, these data are often unavailable. the southern elephant seal (mirounga leonina) consumes large quantities of fish and squid prey in the southern ocean relative to other marine mammals; however, how diet varies relative to seasonal and spatial foraging behaviour is unknown. we used fatty acid (fa) signature analysis of 63 blubber co ... | 2003 | 12816642 |
| blood chemistry in southern elephant seal mothers and pups during lactation reveals no effect of handling. | serum clinical chemistry parameters were examined in lactating southern elephant seal mirounga leonina mothers and their pups from the declining macquarie island population. there were significant changes in serum values from 2 to 21 days postpartum in both nursing mothers (increase: inorganic phosphate; decrease: creatinine, potassium, chloride, cholesterol, total protein, albumin, globulin, aspartate aminotransferase, creatine kinase) and suckling pups (increase: inorganic phosphate, globulin, ... | 2002 | 12208307 |
| facklamia miroungae sp. nov., from a juvenile southern elephant seal (mirounga leonina). | an unusual gram-positive, catalase-negative, facultatively anaerobic, coccus-shaped organism that originated from a juvenile elephant seal was characterized by phenotypic and molecular taxonomic methods. comparative 16s rrna gene sequencing showed that the unknown coccus represents a new subline within the genus facklamia. the unknown strain was readily distinguishable from all currently recognized species of the genus facklamia (facklamia hominis, facklamia languida, facklamia ignava, facklamia ... | 2001 | 11491339 |
| postweaning duration and body composition changes in southern elephant seal (mirounga leonina) pups at king george island. | weaning mass in southern elephant seals is highly variable, the heaviest pups being three times as heavy as the lightest ones. after weaning, pups undergo an extensive postweaning period in which they draw on their reserves. to quantify the energy expenditure during the postweaning period, changes in mass, body composition, and postweaning duration were measured in southern elephant seals at king george island, south shetland islands, antarctica. overall, mean pup weaning mass was 154 +/- 26 kg ... | 2001 | 11436137 |
| lipid composition of blood platelets and erythrocytes of southern elephant seal (mirounga leonina) and antarctic fur seal (arctocephalus gazella). | erythrocyte and blood platelet phospholipid compositions were studied in three elephant seals and two fur seals, two species of marine mammals living in the subantarctic region feeding on preys rich in (n-3) polyunsaturated fatty acids. results were compared with those reported for related species and humans. in erythrocytes, the phospholipid (pl) and cholesterol (chol) contents were lower in pinnipeds than in humans. phosphatidylcholine (pc) levels were higher in elephant seals than in fur seal ... | 2000 | 10825663 |
| molecular genetic diversity and evolution at the mhc dqb locus in four species of pinnipeds. | variation was investigated at exon 2 (including part of the putative peptide-binding region) of the class ii major histocompatibility complex (mhc) dqb locus for two congeneric phocid seal species and two congeneric otariid seal species. polymorphism in one phocid species, the southern elephant seal (mirounga leonina), was comparable to that seen in human populations, while the other phocid, the northern elephant seal (mirounga angustirostris), has been through a severe population bottleneck and ... | 1999 | 10335654 |
| immunoglobulin m serum levels in females and pups of southern elephant seal (mirounga leonina) during the suckling period. | this paper reports immunoglobulin m (igm) levels in serum samples from eight female-pup pairs of southern elephant seals (mirounga leonina), at king george island, antarctica. igm levels were determined on sera obtained from sequential sampling throughout the suckling period (approximately 23 days). the igm concentration in southern elephant seal serum was measured by single radial immunodiffusion on agarose plates. female igm levels (123.5-613.0 mg/dl, n = 8) were significantly higher than pup ... | 1998 | 9683413 |
| plasma concentrations of 25-hydroxyvitamin-d3 (calcifediol) as an indicator of ultraviolet radiation. | vitamin d3 is produced in the skin of animals and humans by the sun's ultraviolet rays (uvb region, 290-315 nm). the main metabolite 25-hydroxyvitamin-d3 has a seasonal variation, depending on the ultraviolet radiation. in the antarctic preliminary investigations on penguins (pygoscelis papua), female sea elephants (mirounga leonina), and humans showed that there was an increase in plasma 25-hydroxyvitamin-d3 concentrations during uv-exposure in all three species. this metabolite can therefore b ... | 1993 | 8305094 |
| concentrations, metabolic clearance rates, production rates and plasma binding of cortisol in antarctic phocid seals. | we have reported previously that plasma of the weddell seal, a member of the phocid family, contains a very high concentration of cortisol. the present study was undertaken to determine whether high cortisol levels were common to seals in the antarctic environment, or to other phocidae, and to determine the mechanism of the hypercortisolaemia. high levels of cortisol (0.82-2.38 mumol/l) were found in 4 phocidae (weddell, crabeater, leopard and southern elephant seals), whereas levels in a member ... | 1993 | 8237255 |
| disease and injury in the southern elephant seal. | disease and injury was recorded in 170 tagged soughern elephant seals (mirounga leonina) on the antarctic continent. trauma due to interspecific predation was the most common disorder. no small seals were observed with lesions attributable to this in the antarctic population. this finding differs from data recorded in a sub-antarctic (macquarie island) population where seals of all class sizes exhibit lesions due to interspecific trauma. no external parasites were observed in the antarctic popul ... | 1977 | 856149 |
| summer and winter cycles in plasma melatonin levels in the elephant seal (mirounga leonina). | plasma melatonin concentration of immature male elephant seals was determined by radioimmunoassay. comparison of concentrations during two 24-h periods, one in midsummer and one in midwinter, showed that there was a marked circadian cycle in winter which was greatly modified during the long day length of summer. it is suggested that in summer there was sufficient ambient lighting during the night hours to depress the nocturnal rise in plasma melatonin. the complexity of pineal cycles in the natu ... | 1979 | 549553 |
| brucella antibody seroprevalence in antarctic seals (arctocephalus gazella, leptonychotes weddellii and mirounga leonina). | brucellosis is a worldwide infectious zoonotic disease caused by gram-negative bacteria of the genus brucella, and brucella infections in marine mammals were first reported in 1994. a serosurvey investigating the presence of anti-brucella antibodies in 3 antarctic pinniped species was undertaken with a protein a/g indirect enzyme-linked immunosorbent assay (ielisa) and the rose bengal test (rbt). serum samples from 33 weddell seals leptonychotes weddelli were analysed, and antibodies were detect ... | 2013 | 23999701 |
| relating diving behavior and antioxidant status: insights from oxidative stress biomarkers in the blood of two distinct divers, mirounga leonina and arctocephalus australis. | pinnipeds rely upon diving to perform essential activities, including foraging. as pulmonated animals, oxygen privation experienced during submergence represents a considerable challenge both physiologically and biochemically. routine exposure to hypoxia and the rapid transitions between ischemia/reperfusion of tissues leads to extremely high reactive oxygen species (ros) production, which must be opposed by antioxidant defenses to avoid oxidative stress. the diving behaviors and capabilities of ... | 2014 | 24607367 |
| detection of toxoplasma gondii antibodies in antarctic pinnipeds. | the presence of toxoplasma gondii antibodies was investigated in antarctic marine mammals. two hundred and eleven sera from different species of pinnipeds collected in years 2007, 2010 and 2011 from different locations in the south shetland islands and antarctic peninsula were analysed using a commercially available agglutination test kit. the presence of antibodies (titres ≥ 1:25) against t. gondii was detected in a total of 28 animals (13.3%). amongst animal species, percentages of detection w ... | 2012 | 22726387 |
| foraging fidelity as a recipe for a long life: foraging strategy and longevity in male southern elephant seals. | identifying individual factors affecting life-span has long been of interest for biologists and demographers: how do some individuals manage to dodge the forces of mortality when the vast majority does not? answering this question is not straightforward, partly because of the arduous task of accurately estimating longevity in wild animals, and of the statistical difficulties in correlating time-varying ecological covariables with a single number (time-to-event). here we investigated the relation ... | 2012 | 22505993 |
| effects of physiological state on duration of sedation in southern elephant seals. | one hundred eighty-one female and thirteen postweanling pup southern elephant seals (mirounga leonina) were sedated using a combination of ketamine hydrochloride and xylazine hydrochloride. physiological state had a profound effect on response of the animals to sedation. physiologically stressed postlactation and postpartum cows had significantly longer periods of sedation than pre-molting females or recently weaned pups. induction time was not affected by physiological status. dose rates are re ... | 1989 | 2810559 |
| 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 ... | 2016 | 26646351 |
| spatially explicit estimates of prey consumption reveal a new krill predator in the southern ocean. | development in foraging behaviour and dietary intake of many vertebrates are age-structured. differences in feeding ecology may correlate with ontogenetic shifts in dispersal patterns, and therefore affect foraging habitat and resource utilization. such life-history traits have important implications in interpreting tropho-dynamic linkages. stable isotope ratios in the whiskers of sub-yearling southern elephant seals (mirounga leonina; n = 12) were used, in conjunction with satellite telemetry a ... | 2014 | 24516515 |
| detection of a novel genotype of cryptosporidium in antarctic pinnipeds. | a study was conducted to investigate the presence of cryptosporidium and giardia in antarctic marine mammals. a total of 270 faecal samples from different species of pinnipeds from different locations in the south shetland islands and antarctic peninsula were analysed by immunofluorescence microscopy and pcr. cryptosporidium was detected by pcr in three samples from southern elephant seals (mirounga leonina) and 2 weddell seals (leptonychotes weddellii). however, no oocysts were observed in any ... | 2013 | 23021408 |
| speciation, population structure, and demographic history of the mojave fringe-toed lizard (uma scoparia), a species of conservation concern. | the north american deserts were impacted by both neogene plate tectonics and quaternary climatic fluctuations, yet it remains unclear how these events influenced speciation in this region. we tested published hypotheses regarding the timing and mode of speciation, population structure, and demographic history of the mojave fringe-toed lizard (uma scoparia), a sand dune specialist endemic to the mojave desert of california and arizona. we sampled 109 individual lizards representing 22 insular dun ... | 2014 | 25360285 |
| 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 ... | 1993 | 8457634 |
| the immunocompetence handicap hypothesis in two sexually dimorphic pinniped species--is there a sex difference in immunity during early development? | the 'immunocompetence handicap hypothesis' predicts that highly sexually dimorphic and polygynous species will exhibit sex differences in immunity. we tested this hypothesis in southern elephant and grey seals during their early development by measuring the following parameters: leucocyte counts, serum igg levels, erythrocyte sedimentation rate and haematocrit. we failed to find any differences due to sex as assessed by the parameters investigated. animals were sampled longitudinally during thei ... | 2006 | 12697319 |
| 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%), ... | 2013 | 23145888 |
| 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 ... | 1991 | 1750175 |
| a new method to quantify within dive foraging behaviour in marine predators. | studies on diving behaviour classically divide a dive into three phases: the descent, bottom and ascent phases, with foraging assumed to occur during the bottom phase. the greater complexity of dive revealed through modern, high resolution data highlights the need to re-assess this approach and to consider a larger number of phases within individual dives. two southern elephant seals (ses) were fitted with a head mounted time depth recorder (tdr) and an accelerometer from which prey capture atte ... | 2014 | 24922323 |
| metabolic biochemistry and the making of a mesopelagic mammal. | large seals such as northern and southern elephant seals and weddell seals are able to dive for startling duration and enormous depth. the current dive duration record is 120 minutes (recorded for the southern elephant seal); the current depth record is 1.5 km (recorded for the northern elephant seal). equally striking is the widespread observation that these seals when at sea spend close to 90% of the time submerged and often at great depth. for practical purposes, these species can be viewed a ... | 1992 | 1612137 |
| arteriovenous anastomoses in the skin of seals. i. the weddell seal leptonychotes weddelli and the elephant seal mirounga leonina (pinnipedia: phocidae). | the structure, distribution, density and innervation of arteriovenous anastomoses (avas) have been compared in the skin of weddell and elephant seals, as part of a study of the structure and function of arteriovenous anastomoses in mammals. in both genera avas were coiled vessels with the segmental structure typical of "epithelioid" anastomoses and possessed a dense peripheral adrenergic innervation. in both weddell and elephant seals there was no statistically significant difference between the ... | 1978 | 666019 |
| estimating resource acquisition and at-sea body condition of a marine predator. | 1. body condition plays a fundamental role in many ecological and evolutionary processes at a variety of scales and across a broad range of animal taxa. an understanding of how body condition changes at fine spatial and temporal scales as a result of interaction with the environment provides necessary information about how animals acquire resources. 2. however, comparatively little is known about intra- and interindividual variation of condition in marine systems. where condition has been studie ... | 2013 | 23869551 |
| plasma melatonin concentration in neonatal northern elephant seals, mirounga angustirostris. | the development of pineal function in northern elephant seals was examined in an attempt to understand the physiological basis for previously observed high daytime levels of melatonin in neonatal southern elephant seals. pineal glands from four northern elephant seal pups, estimated age less than 1 week, weighted 3.0 +/- 0.80 g, which was significantly less than that previously found in southern elephant seals (4.6 +/- 0.35 g). midday concentrations of plasma melatonin in pups averaged more than ... | 1994 | 7828030 |
| decadal changes in habitat characteristics influence population trajectories of southern elephant seals. | understanding divergent biological responses to climate change is important for predicting ecosystem level consequences. we use species habitat models to predict the winter foraging habitats of female southern elephant seals and investigate how changes in environmental variables within these habitats may be related to observed decreases in the macquarie island population. there were three main groups of seals that specialized in different ocean realms (the sub-antarctic, the ross sea and the vic ... | 2017 | 28590592 |
| estimation and simulation of foraging trips in land-based marine predators. | the behavior of colony-based marine predators is the focus of much research globally. large telemetry and tracking data sets have been collected for this group of animals, and are accompanied by many empirical studies that seek to segment tracks in some useful way, as well as theoretical studies of optimal foraging strategies. however, relatively few studies have detailed statistical methods for inferring behaviors in central place foraging trips. in this paper we describe an approach based on h ... | 2017 | 28470722 |
| multiple nuclear-gene phylogenies: application to pinnipeds and comparison with a mitochondrial dna gene phylogeny. | phylogenetic analyses of closely related species should use information from multiple, independent genes with relatively high rates of sequence evolution. to investigate species for which there are few prior sequence data for single-copy nuclear (scndna) genes, primers for gene amplification can be designed to highly conserved regions of exons in order to amplify both coding (exons) and noncoding (introns) sequences. we have explored this approach in a phylogenetic analysis of six species of pin ... | 1994 | 8015430 |
| southern elephant seals (mirounga leonina linn.) depredate toothfish longlines in the midnight zone. | humans have devised fishing technologies that compete with marine predators for fish resources world-wide. one such fishery for the patagonian toothfish (dissostichus eleginoides) has developed interactions with a range of predators, some of which are marine mammals capable of diving to extreme depths for extended periods. a deep-sea camera system deployed within a toothfish fishery operating in the southern ocean acquired the first-ever video footage of an extreme-diver, the southern elephant s ... | 2017 | 28234988 |
| variability in sea ice cover and climate elicit sex specific responses in an antarctic predator. | contrasting regional changes in southern ocean sea ice have occurred over the last 30 years with distinct regional effects on ecosystem structure and function. quantifying how antarctic predators respond to such changes provides the context for predicting how climate variability/change will affect these assemblages into the future. over an 11-year time-series, we examine how inter-annual variability in sea ice concentration and advance affect the foraging behaviour of a top antarctic predator, t ... | 2017 | 28233791 |
| seal mothers expend more on offspring under favourable conditions and less when resources are limited. | in mammals, maternal expenditure on offspring is a complex mix of several factors including the species' mating system, offspring sex and the condition and age of the mother. while theory suggests that in polygynous species mothers should wean larger male offspring than females when resources and maternal conditions allow, the evidence for this remains equivocal. southern elephant seals are highly dimorphic, polygynous capital breeders existing in an environment with highly variable resources an ... | 2017 | 27859273 |
| population differentiation in the context of holocene climate change for a migratory marine species, the southern elephant seal. | understanding observed patterns of connectivity requires an understanding of the evolutionary processes that determine genetic structure among populations, with the most common models being associated with isolation by distance, allopatry or vicariance. pinnipeds are annual breeders with the capacity for extensive range overlap during seasonal migrations, establishing the potential for the evolution of isolation by distance. here, we assess the pattern of differentiation among six breeding colon ... | 2016 | 27012933 |
| elephant seal genetic variation and the use of simulation models to investigate historical population bottlenecks. | because the northern elephant seal (mirounga angustirostrus) was heavily exploited during the 19th century, it experienced an extreme population bottleneck. since then, under legislative protection in the united states and mexico, northern elephant seals have recovered dramatically in number, although their genomic diversity was greatly reduced, apparently as a consequence of the bottleneck. in this study we investigated dna sequence diversity in two mtdna regions (the control region and 16s rna ... | 2008 | 7505788 |
| bio-physical characterisation of polynyas as a key foraging habitat for juvenile male southern elephant seals (mirounga leonina) in prydz bay, east antarctica. | antarctic coastal polynyas are persistent open water areas in the sea ice zone, and regions of high biological productivity thought to be important foraging habitat for marine predators. this study quantified southern elephant seal (mirounga leonina) habitat use within and around the polynyas of the prydz bay region (63°e- 88°e) in east antarctica, and examined the bio-physical characteristics structuring polynyas as foraging habitat. output from a climatological regional ocean model was used to ... | 2017 | 28902905 |
| three-dimensional space use during the bottom phase of southern elephant seal dives. | in marine pelagic ecosystems, the spatial distribution of biomass is heterogeneous and dynamic. at large scales, physical processes are the main driving forces of biomass distribution. at fine scales, both biotic and abiotic parameters are likely to be key determinants in the horizontal and vertical distribution of biomass, with direct consequences on the foraging behaviour of diving predators. however, fine scale three-dimensional (3d) spatial interactions between diving predators and their pre ... | 2017 | 28861272 |
| five decades on: use of historical weaning size data reveals that a decrease in maternal foraging success underpins the long-term decline in population of southern elephant seals (mirounga leonina). | | 2017 | 28301546 |
| big data analyses reveal patterns and drivers of the movements of southern elephant seals. | the growing number of large databases of animal tracking provides an opportunity for analyses of movement patterns at the scales of populations and even species. we used analytical approaches, developed to cope with "big data", that require no 'a priori' assumptions about the behaviour of the target agents, to analyse a pooled tracking dataset of 272 elephant seals (mirounga leonina) in the southern ocean, that was comprised of >500,000 location estimates collected over more than a decade. our a ... | 2017 | 28273915 |
| acoustic measurements of post-dive cardiac responses in southern elephant seals (mirounga leonina) during surfacing at sea. | measuring physiological data in free-ranging marine mammals remains challenging, owing to their far-ranging foraging habitat. yet, it is important to understand how these divers recover from effort expended underwater, as marine mammals can perform deep and recurrent dives. among them, southern elephant seals (mirounga leonina) are one of the most extreme divers, diving continuously at great depth and for long duration while travelling over large distances within the southern ocean. to determine ... | 2017 | 28202583 |
| marine bioluminescence: measurement by a classical light sensor and related foraging behavior of a deep diving predator. | bioluminescence is produced by a broad range of organisms for defense, predation or communication purposes. southern elephant seal (ses) vision is adapted to low-intensity light with a peak sensitivity, matching the wavelength emitted by myctophid species, one of the main preys of female ses. a total of 11 satellite-tracked female sess were equipped with a time-depth-light 3d accelerometer (tdr10-x) to assess whether bioluminescence could be used by sess to locate their prey. firstly, we demonst ... | 2017 | 28425091 |
| quasi-planktonic behavior of foraging top marine predators. | monitoring marine top predators is fundamental for assessing the health and functioning of open ocean ecosystems. although recently tracking observations have substantially increased, factors determining the horizontal exploration of the ocean by marine predators are still largely unknown, especially at the scale of behavioral switches (1-100 km, days-weeks). it is commonly assumed that the influence of water movement can be neglected for animals capable of swimming faster than the current. here ... | 2015 | 26666350 |
| fishing for drifts: detecting buoyancy changes of a top marine predator using a step-wise filtering method. | in southern elephant seals (mirounga leonina), fasting- and foraging-related fluctuations in body composition are reflected by buoyancy changes. such buoyancy changes can be monitored by measuring changes in the rate at which a seal drifts passively through the water column, i.e. when all active swimming motion ceases. here, we present an improved knowledge-based method for detecting buoyancy changes from compressed and abstracted dive profiles received through telemetry. by step-wise filtering ... | 2015 | 26486362 |
| integrative modelling of animal movement: incorporating in situ habitat and behavioural information for a migratory marine predator. | a fundamental goal in animal ecology is to quantify how environmental (and other) factors influence individual movement, as this is key to understanding responsiveness of populations to future change. however, quantitative interpretation of individual-based telemetry data is hampered by the complexity of, and error within, these multi-dimensional data. here, we present an integrative hierarchical bayesian state-space modelling approach where, for the first time, the mechanistic process model for ... | 2013 | 23135676 |
| how large is large: estimating ecologically meaningful isotopic differences in observational studies of wild animals. | in ecological studies of wildlife movements and foraging, bio-logging and isotopic data are routinely collected and increasingly analyzed in tandem. such analyses have two shortcomings: (1) small sample size linked with the number of telemetric tags that can be deployed, and (2) the observational nature of isotopic gradients. wildlife ecologists are thus put in a statistical conundrum known as the small n, large p problem. | 2012 | 23124655 |
| relationship between chlorophyll a concentration, light attenuation and diving depth of the southern elephant seal mirounga leonina. | recently, a number of antarctic marine environmental studies have used oceanographic parameters collected from instrumented top predators for ecological and physical information. phytoplankton concentration is generally quantified through active measurement of chlorophyll fluorescence. in this study, light absorption coefficient (k(0.75)) was used as an indicator of phytoplankton concentration. this measurement, easy to obtain and requiring low electric power, allows for assessing of the fine sc ... | 2012 | 23082166 |
| dissolved oxygen sensor in animal-borne instruments: an innovation for monitoring the health of oceans and investigating the functioning of marine ecosystems. | the current decline in dissolved oxygen concentration within the oceans is a sensitive indicator of the effect of climate change on marine environment. however the impact of its declining on marine life and ecosystems' health is still quite unclear because of the difficulty in obtaining in situ data, especially in remote areas, like the southern ocean (so). southern elephant seals (mirounga leonina) proved to be a relevant alternative to the traditional oceanographic platforms to measure physica ... | 2015 | 26200780 |
| morphology of the tympanic-basicranial region in mirounga leonina (phocidae, carnivora), postnatal ontogeny and sexual dimorphism. | the auditory region of pinnipeds has seldom been described. here we describe and analyze the ontogenetic trajectory of the tympanic bulla of the southern elephant seal, mirounga leonina (phocidae, mammalia). this species is extremely sexually dimorphic and highly polygynous (organized in harems). we examined 118 specimens, arranged in three age classes (ci, cii, and ciii), ranging from newborn to adults (males and females). to analyze the overall size and shape of the tympanic bulla we performed ... | 2015 | 25827162 |
| stable isotope analyses reveal individual variability in the trophic ecology of a top marine predator, the southern elephant seal. | identifying individuals' foraging strategies is critical to understanding the ecology of a species, and can provide the means to predict possible ecological responses to environmental change. our study combines stable isotope analysis and satellite telemetry to study the variability in individual foraging strategies of adult female southern elephant seals (mirounga leonina). our hypothesis is that female elephant seals from the western antarctica peninsula (wap) display individual specialization ... | 2012 | 22139429 |
| serum leptin concentration during the terrestrial phase of the southern elephant seal mirounga leonina (carnivora: phocidae). | this study aimed to verify the serum leptin concentration during the terrestrial phase of the southern elephant seal (mirounga leonina) on elephant island (south shetlands, antarctica). sera from 25 adult southern elephant seals were analyzed. leptin concentration was determined using the 125i radioimmunoassay method. total protein, triglycerides, and cholesterol concentration were measured by spectrophotometric methods. seals were grouped by sex and their physiological status (reproducing or mo ... | 2004 | 15504391 |
| in situ measures of foraging success and prey encounter reveal marine habitat-dependent search strategies. | predators are thought to reduce travel speed and increase turning rate in areas where resources are relatively more abundant, a behavior termed "area-restricted search." however, evidence for this is rare, and few empirical data exist for large predators. animals exhibiting foraging site fidelity could also be spatially aware of suitable feeding areas based on prior experience; changes in movement patterns might therefore arise from the anticipation of higher prey density. we tested the hypothes ... | 2011 | 21797154 |
| how elephant seals (mirounga leonina) adjust their fine scale horizontal movement and diving behaviour in relation to prey encounter rate. | understanding the diving behaviour of diving predators in relation to concomitant prey distribution could have major practical applications in conservation biology by allowing the assessment of how changes in fine scale prey distribution impact foraging efficiency and ultimately population dynamics. the southern elephant seal (mirounga leonina, hereafter ses), the largest phocid, is a major predator of the southern ocean feeding on myctophids and cephalopods. because of its large size it can car ... | 2016 | 27973587 |
| southern elephant seals replenish their lipid reserves at different rates according to foraging habitat. | assessing energy gain and expenditure in free ranging marine predators is difficult. however, such measurements are critical if we are to understand how variation in foraging efficiency, and in turn individual body condition, is impacted by environmentally driven changes in prey abundance and/or accessibility. to investigate the influence of oceanographic habitat type on foraging efficiency, ten post-breeding female southern elephant seals mirounga leonina (ses) were equipped and tracked with bi ... | 2016 | 27902786 |
| assessment of scale-dependent foraging behaviour in southern elephant seals incorporating the vertical dimension: a development of the first passage time method. | 1. identifying the spatial scales at which top marine predators forage is important for understanding oceanic ecosystems. several methods quantify how individuals concentrate their search effort along a given path. among these, first-passage time (fpt) analysis is particularly useful to identify transitions in movement patterns (e.g. between searching and feeding). this method has mainly been applied to terrestrial animals or flying seabirds that have little or no vertical component to their for ... | 2008 | 18513336 |
| variations in behavior and condition of a southern ocean top predator in relation to in situ oceanographic conditions. | responses by marine top predators to environmental variability have previously been almost impossible to observe directly. by using animal-mounted instruments simultaneously recording movements, diving behavior, and in situ oceanographic properties, we studied the behavioral and physiological responses of southern elephant seals to spatial environmental variability throughout their circumpolar range. improved body condition of seals in the atlantic sector was associated with circumpolar deep wat ... | 2007 | 17693555 |
| juvenile southern elephant seals exhibit seasonal differences in energetic requirements and use of lipids and protein stores. | growing juvenile animals undergo many morphological, physiological, and behavioural changes that influence their energetic requirements, patterns of energy use, and ultimately, their survival and reproductive success. we examined changes in mass loss and body composition of juvenile southern elephant seals (1- and 2-yr-olds) during their two annual haul-outs. at the start and end of the midyear and molt haul-outs, we caught, weighed, and measured 41 and 14 seals, respectively. we measured blubbe ... | 2016 | 15957104 |
| new insights into the cardiorespiratory physiology of weaned southern elephant seals (mirounga leonina). | southern elephant seal (mirounga leonina) pups must strike a balance between conserving energy during their post-weaning fast and simultaneously developing diving abilities to attain nutritional independence. little is known about environmental influences on cardiorespiratory patterns, hence energy use, throughout the 6 week fast. continuous heart rates were recorded for free-ranging, newly weaned southern elephant seals using heart rate time-depth recorders for 5-9 days at sub-antarctic macquar ... | 2015 | 27293733 |
| estimating trans-seasonal variability in water column biomass for a highly migratory, deep diving predator. | the deployment of animal-borne electronic tags is revolutionizing our understanding of how pelagic species respond to their environment by providing in situ oceanographic information such as temperature, salinity, and light measurements. these tags, deployed on pelagic animals, provide data that can be used to study the ecological context of their foraging behaviour and surrounding environment. satellite-derived measures of ocean colour reveal temporal and spatial variability of surface chloroph ... | 2014 | 25427104 |
| age-specific cost of first reproduction in female southern elephant seals. | when to commence breeding is a crucial life-history decision that may be the most important determinant of an individual's lifetime reproductive output and can have major consequences on population dynamics. the age at which individuals first reproduce is an important factor influencing the intensity of potential costs (e.g. reduced survival) involved in the first breeding event. however, quantifying age-related variation in the cost of first reproduction in wild animals remains challenging beca ... | 2014 | 24872464 |
| variation in body condition during the post-moult foraging trip of southern elephant seals and its consequences on diving behaviour. | mature female southern elephant seals (mirounga leonina) come ashore only in october to breed and in january to moult, spending the rest of the year foraging at sea. mature females may lose as much as 50% of their body mass, mostly in lipid stores, during the breeding season due to fasting and lactation. when departing to sea, post-breeding females are negatively buoyant, and the relative change in body condition (i.e. density) during the foraging trip has previously been assessed by monitoring ... | 2014 | 24803471 |
| satellites, the all-seeing eyes in the sky: counting elephant seals from space. | regular censuses are fundamental for the management of animal populations but, are logistically challenging for species living in remote regions. the advent of readily accessible, high resolution satellite images of earth mean that it is possible to resolve relatively small (0.6 m) objects, sufficient to discern large animals. to illustrate how these advances can be used to count animals in remote regions, individual elephant seals (mirounga leonina) were counted using satellite imagery. we used ... | 2014 | 24651378 |
| foraging in the darkness of the southern ocean: influence of bioluminescence on a deep diving predator. | how non-echolocating deep diving marine predators locate their prey while foraging remains mostly unknown. female southern elephant seals (ses) (mirounga leonina) have vision adapted to low intensity light with a peak sensitivity at 485 nm. this matches the wavelength of bioluminescence produced by a large range of marine organisms including myctophid fish, ses's main prey. in this study, we investigated whether bioluminescence provides an accurate estimate of prey occurrence for ses. to do so, ... | 2012 | 22952706 |
| depletion of deep marine food patches forces divers to give up early. | many optimal foraging models for diving animals examine strategies that maximize time spent in the foraging zone, assuming that prey acquisition increases linearly with search time. other models have considered the effect of patch quality and predict a net energetic benefit if dives where no prey is encountered early in the dive are abandoned. for deep divers, however, the energetic benefit of giving up is reduced owing to the elevated energy costs associated with descending to physiologically h ... | 2013 | 22881702 |
| o' mother where wert thou? maternal strategies in the southern elephant seal: a stable isotope investigation. | maternal effects are widespread in ecology and can alter the dynamics of a population. we investigated the impact of maternal foraging strategies on offspring weaning mass--a proxy of maternal foraging success and of offspring survival--in southern elephant seals on îles kerguelen. using 4 years of data, we modelled pup weaning mass as a two-component mixture and used blood stable isotope values to discriminate between maternal foraging strategies previously identified from bio-logging studies. ... | 2012 | 22398171 |
| bottom-up regulation of a pole-ward migratory predator population. | as the effects of regional climate change are most pronounced at polar latitudes, we might expect polar-ward migratory populations to respond as habitat suitability changes. the southern elephant seal (mirounga leonina l.) is a pole-ward migratory species whose populations have mostly stabilized or increased in the past decade, the one exception being the macquarie island population which has decreased continuously over the past 50 years. to explore probable causes of this anomalous trend, we co ... | 2014 | 24619437 |