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SOUTHERN OCEAN

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  • A polygonised bathymetric dataset covering the Southern Ocean. The dataset was compiled from data sourced from the General Bathymetric Chart of the Oceans (GEBCO) Digital Atlas, 2003 edition, and the Antarctic Digital Database, version 4.

  • Environmental variables in the region of the Kerguelen Plateau compiled from different sources and provided in the ascii raster format. Mean surface and seafloor temperature, salinity and their respective amplitude data are available on the time coverage 1955-2012 and over five decades: 1955 to 1964, 1965 to 1974, 1975 to 1984, 1985 to 1994 and 1995 to 2012. N/A was set as the no data reference. Future projections are provided for several parameters: they were modified after the Bio-ORACLE database (Tyberghein et al. 2012). They are based on three IPCC scenarii (B1, AIB, A2) for years 2100 and 2200 (IPCC, 4th report).

  • INDICATOR DEFINITION Count of all adult females, fully weaned pups and dead pups hauled out on, or close to, the day of maximum cow numbers, set for October 15. TYPE OF INDICATOR There are three types of indicators used in this report: 1.Describes the CONDITION of important elements of a system; 2.Show the extent of the major PRESSURES exerted on a system; 3.Determine RESPONSES to either condition or changes in the condition of a system. This indicator is one of: CONDITION RATIONALE FOR INDICATOR SELECTION Elephant seals from Macquarie Island are long distance foragers who can utilise the Southern Ocean both west as far as Heard Island and east as far as the Ross Sea. Thus their populations reflect foraging conditions across a vast area. The slow decline in their numbers (-2.3% annually from 1988-1993) suggests that their ocean foraging has been more difficult in recent decades. Furthermore, interactions with humans are negligible due to the absence of significant overlap in their diet with commercial fisheries. This suggests that changes in 'natural' ocean conditions may have altered aspects of prey availability. It is clear that seal numbers are changing in response to ocean conditions but at the moment these conditions cannot be specified. DESIGN AND STRATEGY FOR INDICATOR MONITORING PROGRAM Spatial Scale: Five beaches on Macquarie Island (lat54 degrees 37' 59.9' S, long 158 degrees 52' 59.9' E): North Head to Aurora Point; Aurora Point to Caroline Cove; Garden Cove to Sandy Bay; Sandy Bay to Waterfall Bay; Waterfall Bay to Hurd Point. Frequency: Annual census on 15th October Measurement Technique: Monitoring the Southern Elephant Seal population on Macquarie island requires a one day whole island adult female census on October 15 and a daily count of cow numbers, fully weaned pups and dead pups on the west and east isthmus beaches throughout October. Daily cow counts during October, along the isthmus beaches close to the Station, provide data to identify exactly the day of maximum numbers. The isthmus counts are recorded under the long-established (since 1950) harem names. Daily counts allow adjustment to the census totals if the day of maximum numbers of cows ashore happens to fall on either side of October 15. Personnel need to be dispersed around the island by October 15 so that all beaches are counted for seals on that day. This has been achieved successfully for the last 15 years. On the day of maximum haul out (around 15th October) the only Elephant seals present are cows, their young pups and adult males. The three classes can be readily distinguished and counted accurately. Lactating pups are not counted, their numbers are provided by the cow count on a 1:1 proportion. The combined count of cows, fully weaned pups and dead pups provides an index of pup production. The count of any group is made until there is agreement between counts to better than +/- 5%. Thus there is always a double count as a minimum; the number of counts can reach double figures when a large group is enumerated. The largest single group on Macquarie Island is that at West Razorback with greater than 1,000 cows; Multiple counts are always required there. RESEARCH ISSUES Much research has been done already to acquire demographic data so that population models can be produced. Thus there will be predicted population sizes for elephant seals on Macquarie Island in 2002 onwards and the annual censuses will allow these predictions to be tested against the actual numbers. The censuses are also a check on the population status of this endangered species. LINKS TO OTHER INDICATORS

  • Current meter S4_212a is one of four current meters deployed off the coast of Casey Station, Australian Antarctic Territory. S4_211a was located in Shannon Bay at 66 degrees 16.727 minutes South, 110 degrees 31.434 minutes West. Further deployment details can be found in the 'Mooring Details' section of the data, as well as a 'Location Map'. The data includes: current speed components, current speed and current direction, a progressive vector diagram of displacement, and water temperature. The data were recorded by the Australian Antarctic Division, and processed by Oceanographic Field Services Pty Ltd. Data was recorded between 3:30am 18 November 1997 (GMT) and 7:30am 29 December 1998 (GMT). The fields in this dataset include: Date Time Speed (centimetres per second) Direction (degrees) Temperature (degrees)

  • This dataset contains records of ice thickness and snow thickness from Mawson, Antarctica. Measurements were attempted on a weekly basis and have been recorded since 1954 and are ongoing, although this record only contains data up until the end of 1989. The observations are not continuous however. The dataset is available via the provided URL. These data were also collected as part of ASAC projects 189 and 741. Logbooks(s): Glaciology Sea Ice Log, Mawson 1969 Glaciology Mawson Sea Ice Logs, 1995-2000

  • This dataset contains records of ice thickness and snow thickness from Davis Antarctica. Measurements were attempted on a weekly basis and have been recorded since 1957 and are ongoing, although data have only been archived here until 2002. The observations are not continuous however. The dataset is available via the provided URL. This data were also collected as part of ASAC projects 189 and 741. Logbook(s): Glaciology Davis Sea Ice Logs 1992-1999

  • Current meter S4_211a is one of four current meters deployed off the coast of Casey Station, Australian Antarctic Territory. S4_211a was located in Shannon Bay at 66 degrees 16.727 minutes South, 110 degrees 31.434 minutes West. Further deployment details can be found in the 'Mooring Details' section of the data, as well as a 'Location Map'. The data includes: current speed components, current speed and current direction, a progressive vector diagram of displacement, and water temperature. The data were recorded by the Australian Antarctic Division, and processed by Oceanographic Field Services Pty Ltd. Data was recorded between 3:30am 18 November 1997 (GMT) and 7:30am 29 December 1998 (GMT). The fields in this dataset include: Date Time Speed (centimetres per second) Direction (degrees) Temperature (degrees)

  • Current meter S4_212b is one of four current meters deployed off the coast of Casey Station, Australian Antarctic Territory. S4_211a was located in Shannon Bay at 66 degrees 16.727 minutes South, 110 degrees 31.434 minutes West. Further deployment details can be found in the 'Mooring Details' section of the data, as well as a 'Location Map'. The data includes: current speed components, current speed and current direction, a progressive vector diagram of displacement, and water temperature. The data were recorded by the Australian Antarctic Division, and processed by Oceanographic Field Services Pty Ltd. Data was recorded between 3:30am 18 November 1997 (GMT) and 7:30am 29 December 1998 (GMT). The fields in this dataset include: Date Time Speed (centimetres per second) Direction (degrees) Temperature (degrees)

  • This study employs data from two satellite-borne instruments namely, the Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) and the Total Ozone Mapping Spectrometer (TOMS). This work was completed as part of an honours project under ASAC project 2210 (UV climate over the Southern Ocean south of Australia, and its biological impact). Further information about the project is available in the word document available for download (extract from the honours thesis). The fields in this dataset are: Region Year Day (Julian Day) Pixels (number of cloud free pixels from SeaWiFS sensor that were available for analysis) Mean Chlorophyll (milligrams per cubic metre) (derived from cloud free pixels) Standard Deviation Ozone (dobson units) from the TOMS sensor (average for whole region).

  • Elephant seals use a suite of physiological and behavioural mechanisms to maximise the time they can be submerged. Of these hypo-metabolism is one of the most important, so this study quantified maximum O2 consumptions relative to dove depth and swim speed. From the abstract of the referenced paper: Heart rate, swimming speed, and diving behaviour were recorded simultaneously for an adult female southern elephant seal during her postbreeding period at sea with a Wildlife Computers heart-rate time depth recorder and a velocity time depth recorder. The errors associated with data storage versus real-time data collection of these data were analysed and indicated that for events of short duration (i.e., less than 10 min or 20 sampling intervals) serious biases occur. A simple model for estimating oxygen consumption based on the estimated oxygen stores of the seal and the assumption that most, if not all, dives were aerobic produced a mean diving metabolic rate of 3.64 mL O2 kg-1, which is only 47% of the field metabolic rate estimated from allometric models. Mechanisms for reducing oxygen consumption while diving include cardiac adjustments, indicated by reductions in heart rate on all dives, and the maintenance of swimming speed at near the minimum cost of transport for most of the submerged time. Heart rate during diving was below the resting heart rate while ashore in all dives, and there was a negative relationship between the duration of a dive and the mean heart rate during that dive for dives longer than 13 min. Mean heart rates declined from 40 beats min-1 for dives of 13 min to 14 beats min-1 for dives of 37 min. Mean swimming speed per dive was 2.1 m s-1, but this also varied with dive duration. There were slight but significant increases in mean swimming speeds with increasing dive depth and duration. Both ascent and descent speeds were also higher on longer dives. Data were collected on Time Depth Recorders (TDRs), and stored in hexadecimal format. Hexadecimal files can be read using 'Instrument Helper', a free download from Wildlife Computers (see the provided URL). Data for this project is the same data that was collected for ASAC projects 769 and 589 (ASAC_769 and ASAC_589).