Ecology of Southern Elephant Seals
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Metadata record for data from ASAC Project 257 See the link below for public details on this project. From the abstracts of some of the referenced papers: Anatomical and physiological studies of southern elephant seals (Mirounga leonina), particularly in the post-natal period, raise questions of relative musculature growth, control of metabolism, circulation and temperature regulation, which could be important in our understanding of these processes in mammals and of their contribution to adaptation to environmental extremes. The diving behaviour of 14 adult southern elephant seals was investigated using time depth recorders. Each of the seals performed some dives that were longer than its theoretical aerobic dive limit. Forty-four percent of all dives made by post-moult females exceeded the calculated limit compared with 7% of those made by postbreeding females and less than 1% of those made by adult males. The extended dives displayed characteristics that suggested they were predominantly foraging dives, although some were apparently rest dives. Dives longer than the calculated aerobic limits often occurred in bouts; the longest consisted of 63 consecutive dives and lasted 2 days. Postmoult females performed longer bouts of extended dives than postbreeding females. Extended surface periods (longer than 30 min) were not related to the occurrence of extended dives or bouts of extended dives. The possible physiological mechanisms that permit such prolonged continuous dives are discussed. Southern elephant seals may increase the aerobic capacity of dives by lowering their metabolism to approximately 40% of the resting metabolic rate on long dives. There is substantial interseal variability in the methods used to cope with long dives. Some animals appear to use phsyiological strategies that allow them to prolong the time available to them at the bottom of a dive, while others use alternative strategies that may limit the time available at the bottom of their dives. Fourteen time-depth-temperature recorders were recovered from adult southern elephant seals (Mirounga leonina) returning to Macqaurie Island to breed or moult. The resulting temperature/depth profiles indicated that all four males spent most of their time in waters lying over the Antarctic Continental Shelf, whereas only one of the ten females spent any time there. Five of the females foraged just off the Antarctic Continental Shelf, and the other five remained near the Antarctic Polar Front. 1) Mark-resight data were analysed for thirteen cohorts from a declining population of southern elephant seals branded at Macquarie Island between 1951 and 1965. 2) First year survival was essential stable during the 1950s at about 46% for females and 42% for males. There was a dramatic fall in first year survival during the 1960s, declinging to less than 2% for both sexes in 1965. Post-year-1 survival did not change between the 1950s and the 1960s. 3) Comparisons with a stable population of southern elephant seals at South Georgia indicated that both first year and adult survival were lower in the Macquarie Island population. There were no changes in the age at first breeding of the Macquarie Island seals during the study, but this was on average 1 year later than at South Georgia. 4) It is hypothesised that the current decline in elephant seal numbers at several of their major breeding islands is due to the populations returning to pre-sealing levels after they had risen to abnormally high levels with the end of commercial exploitation early this century. 5) Possible tests of the hypothesis include studying the diet and foraging behaviour of southern elephant seals to gain an understanding of the predator-prey relationships, continuing to census the Macquarie Island population to determine if the population levels out at around the estimated pre-sealing levels, and monitoring northern elephant seal populations which were also severely exploited but are currently increasing
Biology and Classification of Macquarie Island Echinoderms
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Metadata record for data from ASAC Project 38 See the link below for public details on this project. From the abstracts of the referenced papers: The origin of echinoderms from Macquarie Island in the Southern Ocean is analysed through a novel application of multivariate statistics. Ordinations are produced from a combination of species distribution, bathymetric, habitat and life history data in order to assess patterns of migration. The analyses distinguish groups of species derived from the Kerguelen Plateau, New Zealand and eastern Antarctica. These groups correlate with attributes expected for epiplanktonic dispersal and range expansion along the North and South Macquarie Ridges respectively. There is no convincing evidence for long-distance pelagic dispersal, migration from the abyssal plain or for human translocation of species. The results indicate that taxonomic groups differ in their ability to disperse, and emphasise the importance of depth in biogeographical analyses. Dispersal by range expansion appears to have been more significant than epiplanktonic dispersal and vicariant rather than long-distance dispersal mechanisms are the preferred explanation for some disjunct distribution patterns. Fifty two echinoderm species are recorded from off Macquarie Island and the Macquarie Ridge in the Southern Ocean. One new asteroid Odontohenricia anarea sp. nov. and one new holothurian Trachythyone nelladana sp. nov. are described. The asteroid genus Calvasterias is synonymised with Anasterias. The asteroids Cycethra macquariensis and Asterina hamiltoni are synonymised with Asterina frigida and placed in the same genus Cycethra. The asteroid Ceramaster lennoxkingi is synonymised with C. patagonicus, Solaster dianae with S. notophrynus, and Anasterias sphoerulatus with A. mawsoni. The asteroids Psilaster charcoti, Odontaster penicillatus, Ceramaster patagonicus, Crossaster multispinus, Solaster notophrynus, Pteraster affinis, Henricia studeri, the ophiuroid Ophioplocus incipiens, and the holothurians Paelopatides ovalis, Synallactes challengeri, Laetmogone sp, Taeniogyrus sp are recorded from the island for the first time. The following species previously recorded from Macquarie Island have been re-identified: the asteroids Odontaster auklandensis (=O. penicillatus), Henricia aucklandiae (=H. studeri), Henricia lukinsi (=H. obesa), Smilasterias irregularis (=S. clarkailsa), Anasterias antarctica (=A. directa), and the ophiuroid Ophiacantha pentagona (=O. vilis). The existence at Macquarie Island of the species Hymenaster sp, Goniocidaris umbraculum and Ocnus calcareus require confirmation. The asteroids Anasterias mawsoni, Pteraster affinis, Porania antarctica and Odonaster meridionalis are reported from the shore around Heard Island. The ecology and relationships of echinoderms from Macquarie Island are discussed.
Studies of Beaks and Parasites of Antarctic Cephalopods
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Metadata record for data expected ASAC Project 11 See the link below for public details on this project. From the abstract of the referenced paper: The Australian Antarctic Division carried out an extensive sampling program for pelagic and benthic fauna in Prydz Bay, Antarctica (Indian Ocean sector) in January to March 1991. A total of 341 cephalopod specimens comprising 256 squids and 85 octopods were captured for study. This preliminary report presents capture records of eight species of squids: Brachioteuthis sp., Kondakovia longimena, Bathyteuthis abyssicola, Mastigoteuthis psychophila, Psychroteuthis glacialis, Alluroteuthis antarcticus, Mesonychoteuthis hamiltoni and Galiteuthis glacialis. The Octopods captured are Megalehedone senei and several species of Pareledone. Psychoteuthis glacialis is reported to congregate on the bottom near the shelf edge at the depth of 400-600 metres. No distinctive pattern in diel vertical movement was found for any of the species captured. Evidence suggests the existence of ontogenetic descent in Galiteuthis glacialis. Cephalopod catches from the extensive sampling program for fishes and zooplankton were studied. For the pelagic fauna, half-hour duration IYGPT hauls were taken at three depths at 63 stations evenly distributed over Prydz Bay area. The three depths fished by the IYGPT at each station were near the surface, near the bottom or 800 m whichever was less, and the midpoint between those two depths. The 63 stations coincided with most of the stations used in the zooplankton sampling program which employed an RMT 1 + 8 net and sampled from 0-200 metres. Additionally 21 benthic samples were taken using bottom trawl, fished for half hour duration on the shelf of Prydz Bay.
Spring Phytoplankton Assemblages in the Southern Ocean Between Australia and Antarctica
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This dataset comprises of an excel spreadsheet of data collected on the CLIVAR-SR3 cruise in November to December 2001. The spreadsheet contains plankton and carbon data. From the abstract of the referenced publication: Variations of phytoplankton assemblages were studied in November-December 2001, in surface waters of the Southern Ocean along a transect between the Sub-Antarctic Zone (SAZ) and the Seasonal Ice Zone (SIZ; 46.9-64.9 degrees S; 142-143 degrees E; CLIVAR-SR3 cruise). Two regions had characteristic but different phytoplankton assemblages. Nanoflagellates (less than 20 microns) and pico-plankton (~2 microns) occurred in similar concentrations along the transect, but were dominant in the SAZ, Sub-Antarctic Front (SAF), Polar Front Zone (PFZ) and the Inter-Polar Front Zone (IPFZ), (46.9-56.9 degrees S). Along the entire transect their average cell numbers in the upper 70 m of water column, varied from 300,000 to 1,100,000 cells per litre. Larger cells (greater than 20 microns), diatoms and dinoflagellates, were more abundant in the Antarctic Zone-South (AZ-S) and the SIZ (60.9-64.9 degrees S). In AZ-S and SIZ diatoms ranged between 270,000 and 1,200,000 cells per litre, dinoflagellates from 31,000 to 102,000 cells per litre. A diatom bloom was in progress in the AZ-S showing a peak of 1,800,000 cells per litre. Diatoms were dominated by Pseudo-nitzschia spp., Fragilariopsis spp., and Chaetoceros spp. Pseudo-nitzschia spp. outnumbered other diatoms in the AZ-S. Fragilariopsis spp. were most numerous in the SIZ. Dinoflagellates contained autotrophs (eg Prorocentrum) and heterotrophs (Gyrodinium/Gymnodinium, Protoperidinium). Diatoms and dinoflagellates contributed most to the cellular carbon: 11-25 and 17-124 micrograms of carbon per litre, respectively. Small cells dominated in the northern region characterised by the lowest N-uptake and new production of the transect. Larger diatom cells were prevalent in the southern area with higher values of N-uptake and new production. Diatom and nanoflagellate cellular carbon contents were highly correlated with one another, with primary production, and productivity related parameters. They contributed up to 75% to the total autotrophic C biomass. Diatom carbon content was significantly correlated to nitrate uptake and particle export, but not to ammonium uptake, while flagellate carbon was well correlated to ammonium uptake, but not to export. Diatoms have contributed highly to particle export along the latitudinal transect, while flagellates played a minor role in the export. This work was completed as part of ASAC project 1343 (ASAC_1343). The fields in this dataset are: Station (depth, position, date, comments) Species Cells per millilitre cell carbon - micrograms per litre