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  • 1
    ISSN: 1573-5117
    Keywords: marking ; monitoring ; elephant seals ; Kerguelen Province
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Southern elephant seals Mirounga leonina breed and moult on many subantarctic islands during the austral spring and summer. In the Kerguelen Province the subpopulations of M. leonina at Kerguelen (49°21′S, 70°12′E), Marion (46°54′S, 37°45′E) and Possession (46°25′S, 51°45′E) Islands have declined since 1970 and their present status at Heard Island (53°05′S, 73°30′E) is unknown. Population studies during their terrestrial phase have failed to explain the declines. Long distance movements of individuals between the subpopulations in question and also the Vestfold Hills, Antarctica (68°35′S, 77°58′E) have been recorded. The availability of food resources, competition with rapidly increasing fur seal populations and competition with fishing fleets have all been implicated in their decline. These explanations assume that communal feeding grounds are utilized. As they are predators entirely dependent on marine feeding, a study of their spatial and temporal distribution during their pelagic existence is of the utmost importance. Parameters describing growth, reproduction rates, population dynamics, and feeding ecology of the subpopulations in the Kerguelen Province may furthermore serve as indices of change within the marine ecosystem. The presence of a relatively large and predominantly male nonbreeding population of M. leonina at the Vestfold Hills in Antarctica which originates from the Kerguelen/Heard Island group, and which shows annual return, should be included in the marking and monitoring studies of the Kerguelen stock of southern elephant seals. Studies here, including an update of the size and social structure of the Heard island subpopulation, may elucidate the observed decline of, in particular, the adult bull component of the breeding stock.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2018-08-10
    Description: Germany intends to present the Scientific Committee the background document that provides the scientific basis for the evaluation of marine protected areas (MPAs) in the Weddell Sea. Please note, that the current state of the background document presents a comprehensive yet incomplete first version concerning chapters that have to be (further) developed or revised. The contents and structure of the document reflect also its main objectives, i.e. (i) to set out the general background and context of the establishment of MPAs, (ii) to describe the boundaries of the Weddell Sea MPA Planning Area, (iii) to inform on the data retrieval process, (iv) to provide - for the first time- a comprehensive, yet succinct, general description of the Weddell Sea ecosystem to reflect the state of the science, and additionally to present the results of the various preliminary scientific analyses that were carried out so far within the framework of the MPA Weddell Sea project, and finally (v) to describe future work beyond the development of the scientific basis for the evaluation of a Weddell Sea MPA.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Miscellaneous , NonPeerReviewed
    Format: application/pdf
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  • 3
    Publication Date: 2017-04-07
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , NonPeerReviewed
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  • 4
    Publication Date: 2019-07-17
    Description: A proposed study into the ranging and diving behaviour of Ross seals Ommatophoca rossii in an area of high relative abundance in the eastern Weddell Sea, and their diet through direct (stomach contents and scats) and indirect (dive behaviour, jaw activity recordings and stable isotope analyses) means was turned down for the SANAP research period 2012-2014. The aim was to improve knowledge of the way oceanographic conditions affect one of the four true Antarctic species of seal breeding off the Princess Martha Coast, Antarctica in the King Haakon VII Sea with a view to using Ross seals as bioindicators of environmental change under a scenario of ocean warming, progressive disintegration of the West Antarctic ice-sheet and decrease in sea-ice coverage. Designed to build on earlier SANAP seal research in this area of pack-ice in the late 1970’s and early 1990’s, using the new SA Agulhas II as the research platform, it would apply latest technology such as Conductivity, Temperature, Depth (CTD)-Satellite Relay Data Loggers (SRDLs), Mandible Accelerometers (MACs) and stable isotope analyses to characterise Ross seal distribution, diet and physical characteristics of the water column where they forage. Ross seals are ideal candidates as they made long foraging trips north of the pack-ice into pelagic areas of the Southern Ocean for most of the year (in 2001) and returned to the pack-ice only for short periods to breed and moult. The comprehensive analysis and synthesis of biological and physical data perceivably could make an important contribution to determining relationships between hydrographic features, ocean currents, sea floor characteristics, prey dynamics, and the distribution and abundance of marine top predators. A possible way forward in the use of a top predator as an oceanographic profiler to detailing the structure and function of the pack-ice ecosystem likely affected by global warming is presented.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 5
    Publication Date: 2019-07-17
    Description: Adult female southern elephant seals are predominantly pelagic, coming ashore biannually solely to breed and to moult. The success of the post-moult foraging trip has direct implications for female breeding success and the final weaning weight and future survival of the pup and may impact population fluctuations. In 2007 and 2008, a total of 13 post-moult adult female southern elephant seals from sub-Antarctic Marion Island were tracked via satellite transmitters. Ten of the resulting tracks were completed by recurrence of the female to Marion Island, with mean track durations of 250 days. The total trip distances ranged between 22 810.6 km and 13 169.7 km (mean = 18 980.9 km). Seals tracked in 2008 displayed longer total trip distances (20 450.6 km ± 5362.5 km) than seals tracked in 2007 (16 776.3 km ± 6106.5 km). The mean maximum distance attained was 2 793.9 km ± 845.6 km and did not vary between years. In contrast to southern elephant seals tracked from Kerguelen Island in 2003/2004, adult female seals (this study) travelled extensive distances due west of Marion Island. Only three individuals travelled to and within the Antarctic sea ice during the study period. The remaining animals travelled extensively along the South West Indian Ridge, often resulting in overlap of large portions of the tracks. Tracks displayed areas of restricted movement, which either coincided with areas of higher chlorophyll concentrations, anomalous sea-surface temperatures or mesoscale sea-surface height anomalies. An understanding of the relationships between southern elephant seal female movements and the variability of oceanographic features may help to identify driving forces of Marion Island southern elephant seal population fluctuations. Quantification of heterogeneity within marine habitats is thus necessary in order to further our understanding of such relationships.
    Repository Name: EPIC Alfred Wegener Institut
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  • 6
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 7
    Publication Date: 2019-07-17
    Description: Extended AbstractStudies on wild pinnipeds such as blood and tissue sampling or attachment ofinstruments usually require immobilization. This is particularly true for adult malesouthern elephant seals whose body mass generally exceeds 2 tons, and hence,a suitable chemical restraint is required for any handling. Therefore, both appropriatedrugs and a remote delivery system as generally applied in wild animal research isrequired (CLINE et al., 1969; TRILLMICH and WIESNER, 1979; KOCK, 1987; BUSH,1992). Wild elephant seals are only accessable during their onshore-periods whilebreeding and moulting. At this time, they fast and hence undergo considerablemetabolic changes. The individuals' constitutions are then highly variable, and thereaction to external stimuli ranges from being calm to being aroused. Thereby, thedosage of drugs is hardly to assess, and the response to drugs is variable(HAMMOND and ELSNER, 1977). Estimation of body mass is also difficult sincemoulting males tend to aggregate tightly in large groups when ashore, occasionallylying over and over. The harsh field conditions in polar regions aggravate the workadditionally. Therefore, both a sturdy drug delivery system, and some considerationson the methods of application are recommended.In the present study, 27 animals were immobilized to obtain subcutaneous tissuesamples, and to attach satellite linked dive recorders to their pelage at the end oftheir annual moult. Prior to immobilization, doses were calculated roughly basedon the estimated body mass. Immo-bilization was performed in two steps. Firstly,Large Animal Immobilon® (LA Immobilon®) was injected remotely to achieveinitial sedation (x=0.0009 mg/kg etorphine; 0.0037 mg/kg acepromacine). As thesecond step, if breathing and reflexes occured regularly, ketamine wassubsequently injected by hand to maintain narcosis (x=81 min). Nine casesrequired the application of the etorphine-antidote Large Animal Revivon®(x=0.0052 mg/kg diprenor-phine) injected intraveneously (n=3), intramuscularly(n=5), or sublingually (n=1) to antagonize side effects such as prolonged apneaand/or decrease of reflexes.Results and DiscussionThe total dosages of ketamine required to maintain narcosis (x=1.7 mg/kg) werenegatively correlated with those of LA Immobilon® (p〈0.01). The dosages ofLA Immobilon® were approximatelly 15-30 times lower than recommended forother large-sized mammal species including marine mammals (ALFORT et al.,1974; BORN and KNUTSEN, 1990; GRIFFITH et al., 1993), and the therapeuticrange was low. LA Immobilon® appears nevertheless to be useful as a first-stepimmobilization agent in adult male southern elephant seals owing to its smallvolume required for remote injection, and the possibility of high specificantagonization by Large Animal Revivon®. We nevertheless suggest thatLA Immobilon® should only be used as a kind of pre-medication, not usedrepeatedly in the same individual, and solely if high specific antidote(Large Animal Revivon®) is availlable. It has further to be realized thatLA Immobilon® is potentially dangerous for personnel, especially when usedin remote areas. Therefore, both the specific morphine-antidote for humans(Narcanti®), and trained field personnel should be aboard.
    Repository Name: EPIC Alfred Wegener Institut
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  • 8
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , NonPeerReviewed
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  • 9
    Publication Date: 2019-07-17
    Description: The audible frequency ranges and corresponding hearing thresholds are the most characteristic properties of any auditory system. They are typically displayed in the form of an audiogram as the function of minimal audible sound level in respect to frequency. For about 90% of marine mammal species including all Antarctic seals audiograms have not been measured as yet, and knowledge about their hearing is limited to assumptions based on measurements on similar species and frequency ranges of their own vocalisations, with the underlying assumption that vocalisation frequencies correspond with hearing abilities. However, it is well known that hearing is possible in excess of up to several octaves beyond the vocalisation frequencies since hearing has not only evolved as a function of communication; and marine mammals in particular have evolved to use sound and hearing as their primary means of perceiving their surroundings. Recordings of vocalisations related to reproductive or feeding behaviour as well as measurements of hearing abilities are therefore very relevant to interpret population ecology as well as several other aspects of seal biology.We used electro-encephalography to measure auditory evoked potentials, especially the auditory brainstem responses of immobilised southern elephant seal yearlings. The field study was conducted at the haulout sites of elephant seals close to the Marion Island Research Base (46°54S, 37°45E) from 12 to 24 April 2007. Five 1.5 years old seals were chosen for experiments. We developed a portable experimental set-up in order to test for basic audiogram data. The experiment was focussed on a mapping procedure to identify areas on the seals head most suitable for AEP recordings by seeking for optimal electrode placements, where signal to noise ratios are best. The poster shows the methodological approach, presents first results on audiometric procedures on southern elephant seals, and discusses the ecological relevance of audiometric investigations.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 10
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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