Description: While modern sampling techniques, such as autonomous underwater vehicles, are increasing our knowledge of the fauna beneath Antarctic sea ice of only a few meters in depth, greater sampling difficulties mean that little is known about the marine life underneath Antarctic ice shelves over 100 m thick. In this study, we present underwater images showing the underside of an Antarctic ice shelf covered by aggregated invertebrate communities, most likely cnidarians and isopods. These images, taken at an average depth of 145 m, were obtained with a digital still camera system attached to Weddell seals Leptonychotes weddellii foraging just beneath the ice shelf. Our observations indicate that, similar to the sea floor, ice shelves serve as an important habitat for a remarkable amount of marine invertebrate fauna in Antarctica.

Description: We examined how seabirds might be used to study marine environmental variables, which necessitates knowing location and the value of the variable to be studied. Five systems can potentially be used for determination of location: VHF (Very High Frequency) telemetry, PTT (Platform Terminal Transmitters) telemetry, GLS (Global Location Service) geolocation methods, dead reckoning and GPS (Global Positioning System), each with its own advantages with respect to accuracy, potential number of fixes and size. Temperature and light were used to illustrate potential difficulties in recording environmental variables. Systems currently used on seabirds for measurement of temperature respond slowly to environmental changes; thus, they may not measure sea surface temperature adequately when contact periods with water bodies are too short. Light can be easily measured for light extinction studies, but sensor orientation plays a large role in determining recorded values. Both problems can be corrected. The foraging behaviour of seabirds was also examined in order to identify those features which would be useful for determination of marine environmental variables at a variety of spatial and temporal scales. Area coverage by birds is highly dependent on breeding phase and tends to be concentrated in areas where prey acquisition is particularly enhanced. The identification of these sites may be of particular interest to marine biologists. 'Plungers' and 'divers' are potentially most useful for assessment of variables deeper within the water column, with some divers spending up to 90% of their time sub-surface. Few seabirds exploit the water column deeper than 20 m, although some divers regularly exceed 50 m (primarily penguins and auks), while 2 species dive in excess of 300 m. The wide-ranging behaviour of seabirds coupled, in many instances, with their substantial body size makes them potentially excellent carriers of sophisticated environmental measuring technology; however, the ethical question of how much the well-being of birds can, and should, be compromised by such an approach needs to be carefully considered.

Description: We examined how seabirds might be used to study marine environmental variables, which necessitates knowing location and the value of the variable to be studied. Five systems can potentially be used for determination of location: VHF (Very High Frequency) telemetry, PTT (Platform Terminal Transmitter) telemetry, GLS (Global Location Service) geolocation methods, dead reckoning and GPS (Global Positioning System), each with its own advantages with respect to accuracy, potential number of fixes and size. Temperature and light were used to illustrate potential difficulties in recording environmental variables. Systems currently used on seabirds for measurement of temperature respond slowly to environmental changes; thus, they may not measure sea surface temperature adequately when contact periods with water bodies are too short. Light can be easily measured for light extinction studies, but sensor orientation plays a large role in determining recorded values. Both problems can be corrected. The foraging behaviour of seabirds was also examined in order to identify those features which would be useful for determination of marine environmental variables at a variety of spatial and temporal scales. Area coverage by birds is highly dependent on breeding phase and tends to be concentrated in areas where prey acquisition is particularly enhanced. The identification of these sites may be of particular interest to marine biologists. Plungers and divers are potentially most useful for assessment of variables deeper within the water column, with some divers spending up to 90% of their time sub-surface. Few seabirds exploit the water column deeper than 20 m, although some divers regularly exceed 50 m (primarily penguins and auks), while 2 species dive in excess of 300 m. The wide-ranging behaviour of seabirds coupled, in many instances, with their substantial body size makes them potentially excellent carriers of sophisticated environmental measuring technology; however, the ethical question of how much the well-being of birds can, and should, be compromised by such an approach needs to be carefully considered.

Description: The migratory behaviour of adult male southern elephant seals, Mirounga leonina, from King George Island was studied in relation to sea ice coverage. Fourteen animals were immobilzed and fitted with satellite linked transmitters (Telonics/Wildlife Computers, USA) after the annual moult at their southernmost breeding colony at Stranger Point, King George Island, South Shetland Islands, from March to May 2000. The seals were tracked by Service ARGOS (Toulouse/France) for up to 12 months until March 2001. Daily data of sea ice coverage were derived from the Special Sensor Microwave/Imager (SSM/I) of the Defence Meteorological Satellite Program (DMSP).The bulls moved south-eastward along the shelf margin east of the Antarctic Peninsula reaching their southernmost locations in the interior pack ice of the Weddell Sea in May 2000.Here they concentrated their foraging close to the northern sill of the Filchner Trough. This region corresponds to a divergence of the Antarctic Coastal Current which forms the southern limb of the Weddell Gyre. Upwelling in this area might cause vertical transport of organic material which correlates with increased prey availability for top predators through food web linkages. In August 2000 the remaining bulls with functional transmitters returned northwards to their breeding sites, mainly King George Island.The migration routes of the bulls differ considerably from those of cows and weaned pups of both sexes which moved westward from King George Island into the Pacific sector of the Antarctic Ocean as revealed in a previous tracking study. It needs to be verified whether such separation is maintained within and between years.

Description: Twenty-seven adult male southern elephant seals were immobilised to enableattachment of satellite transmitters and to obtain tissue samples. Large AnimalImmobilon (LA Immobilon) was injected remotely to achieve initial sedation(x=0,0009 mg/kg etorphine; 0.0037 mg/kg acepromacine) while ketamine wasinjected manually on demand to maintain narcosis (x=81 min). The total dosages(x=1,7 mg/kg) of ketamine required were negatively correlated with those ofLA Immobilon (p 〈 0,01). The dosages of LA Immobilon were approximately15 to 30 times lower than recommended for other large-sized mammal species,and the therapeutic range was low. Nine cases required the application of theetorphine-antidote Large Animal Revivon (x=0,0052 mg/kg diprenorphine) injectedintraveneously (n=3), intramuscularly (n=5), or sublingually (n=1). LA Immobilonappears to be useful to attain immobilisation in adult male southern elephantseals by remote injection owing to its high potency and hence small volume required.It must, however, be used sparingly and ideally for initial sedation due to its potentialdanger and narrow therapeutic margin.

Description: The microscopic anatomy of the eye of the Weddell seal was studied with various light and electronmicroscopic methods with aview to correlating morphological findings with the biology of this seal whichis adapted to the extremes of the Antarctic environment and to extreme diving excursions into the lightlessdepth of the sea. In the retina and area centralis was found but no fovea centralis. Thedensily packed photoreceptors consist exclusively of highly differenciated rods, which inprimates detect light at low intensity but have rather poor image discrimination.The ganglion cells are relatively scarce, suggesting a high degree of convergence of thelight-sensitive cells on the ganglion cells. The pigment epithelium is almost devoid ofpigment granules. The extensive tapetum lucidum is about 400-500 micrometer thickand is composed of about 30 layers of specialized cells. the cornea is 650 (center)to 800-900 (periphery) micrometer thick. Its structure and glucosaminoglycan histochemistrycorrespond to that of other mammals. The iridocorneal angle is unusually deep andpervaded by an elaborate trabecular meshwork, which together with a complex canalof Schlemm can be correlated with the ability to absorb large amounts of fluid. Theciliary muscle and its antagonist, the membrane of Bruch, are poorly developed., suggestingrelatively poor abilities of accomodation. The combination of a well-developed tapetumlucidum, and unpigmented pigment epithelium, well-developed rods, and a high number of rodconverging on only few ganglion cells is obviously an adaptation to an extreme lightsensitivity, enabling the animal to make use of the little light available in the deep sea.

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.