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MACQUARIE ISLAND

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  • 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).

  • 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

  • Because of the inaccessibility of the deep-ocean floor, our knowledge about the composition and structure of the oceanic crust is very limited. Macquarie Island is the only fragment of ocean crust exposed above sea-level in the world, providing a unique opportunity to study the ocean crust directly in unprecedented detail. From the abstract of the referenced paper: Macquarie Island preserves largely in-situ Miocene oceanic crust and mantle formed at a slow-spreading ridge. The crustal section on the island does not conform to a simple 'layer cake pseudo-stratigraphy', but is the result of multiple magmatic episodes. Macquarie Island crust did not grow by top-down cooling, but rather from the base up. Peridotites cooled first and formed the basement into which gabbro plutons were intruded. This was followed by cooling and deformation, and by intrusion of dykes that fed a sheeted dyke-basalt complex. Finally, lava filled grabens were formed. These relative age relations rule out simple co-genetic relations between rock units.

  • Seal colonies on Macquarie Island. This is a polygon dataset stored in the Geographical Information System (GIS). Attributes include the species name and whether breeding occurs within the area represented. The species include Southern Elephant and Fur.

  • Flying bird breeding colonies on Macquarie Island. This is a polygon dataset stored in the Geographical Information System (GIS). Attributes include the species name and the time of the year during which breeding occurs. The species include Black-browed Albatross, Grey-headed albatross, Southern Giant-Petrel and Wandering Albatross.

  • This is a polygon GIS dataset representing penguin colonies on Macquarie Island. The penguin species include Gentoo, King, Rockhopper and Royal.

  • The only work that went ahead as part of this ASAC project was to look at Penguins restraint and stress level (see the referenced paper below). From the paper: During most research on penguins it is necessary to temporarily immobilise the birds at some time (to weigh, mark, or attach instruments). Although many penguin species seem unconcerned about a human's presence, a single approaching person has been shown to increase the birds heart rate, suggesting that the animal is aware and may be stressed. Corticosterone is one of the hormones regulating the stress reaction in birds, and in turn regulates that stress caused by immobilisation. As captured and bag restrained Adelie penguins show a three fold increase in heart rate, we can presume that this is a very stressful immobilisation technique. Restricting the stress reaction is particularly important during the breeding season to avoid nest desertion, or loss of eggs and chicks. The subject of this paper is to present a less stressful method for restraining penguins. 38 mature, male Gentoo penguins in good physical condition were used to test bag restraint methods. Resting animals were caught on the Macquarie Island Isthmus. 59 animals were used to test the effect of hood restraint methods. There was a significant increase in corticosterone concentrations in the blood of bag restrained penguins within 10 minutes of restraint. Between 10 and 15 minutes, further changes were not significant. After 20 minutes, however, there was a second significant increase, when compared to the levels at 15 minutes. Upon release all birds were unconscious; they then showed symptoms of hysteria, such as disorientation and shaking of the head. Corticosterone levels in the blood of hooded penguins rose significantly after 5 minutes. After 10 minutes, the mean concentration showed a tendency to decrease, when compared to the 5 minute levels. This, however, did not differ significantly to concentrations immediately after restraint. After 20 minutes concentrations rose again, and were again significantly higher than at the same time of restraint and after 15 minutes. Both groups showed the same levels of corticosterone upon restraint. Hood restraint led overall to a lower increase in corticosterone levels than restraint with a bag. After 5, 10, 15 and 20 minutes, statistically significant lower levels in the blood were detected in hood restrained birds. The penguin's reaction to both restraint methods was identical in two respects: There was no significant increase in corticsterone concentration between 10 and 15 minutes. Secondly, concentrations were significantly higher after 20 minutes than at 15 minutes.

  • This database is a compendium of histories of known age seals (leopard) from observations across the Southern Ocean but primarily focussed on Macquarie Island. Although the following information pertains to Elephant Seals, it is assumed similar procedures were undertaken with the Leopard Seals between 1957 and 1999: "At Macquarie Island 1000 seals were weighed per annum between 1993-2003 at birth and individually marked with two plastic flipper tags in the inter-digital webbing of their hind flippers. These tagged seals were weighed again at weaning, when length, girth, fat depth, and flipper measurements were made. Three weeks after weaning 2000 seals were permanently and individually marked by hot-iron branding. Recaptures and re-weighings of these known aged individuals were used to calculate growth and age-specific survival of the seals. Similar data were collected from elephant seals between 1950 and 1965 when seals were individually marked by hot-iron branding. Mark-recapture data from these cohorts were used to assess the demography of the declining population. Length and mass data were also collected for these cohorts and were used, for the first time, to assess the growth of individual seals without killing them." The database was held by the Australian Antarctic Data Centre, but was taken offline due to maintenance problems. A snapshot of the database was taken in June 2018 and stored in an access database. This work was completed as part of ASAC project 90.

  • Macquarie Island offers a rare land-based cross-section through the deep ocean floor, which covers 60% of our Earth. It formed 11 million years ago as slow spreading crust, which has had minimal study compared to more common fastspreading crust. Does the difference in spreading speed produce different crustal geometry, composition, hydrothermal fluids, and cycling of sulfur between ocean and crust? To gain insights to these and related questions, we propose to study uplifted and eroded sections through a series of fault zones, spaced along the length of Macquarie Island, which were the last magmatic, structural and hydrothermal events to occur before shifting stresses drove the seafloor up to form the Macquarie Ridge mountain chain. This dataset is a summary of samples obtained by Mr Steve Lewis for the purposes of investigating hydrothermal alteration in oceanic crust on Macquarie Island. Samples derive from the major lake, Lusitania Bay, and Caroline Cove areas. Each sample consists of rock chips up to a maximum of 1 kg. Samples were all obtained by hand with a geological hammer. The fields in this dataset are: Sample Easting Northing Date Location Transect Details

  • From the abstract of one of the referenced papers: The estimated breeding population of wandering albatrosses on Macquarie Island increased from 17 in 1956 to a maximum of 97 in 1966, and then declined at an average rate of 8.1% per year. Mark-recapture analysis shows that the population is not closed (ie subject to immigration and emigration). The decline is correlated with the onset of large-scale fishing for tuna in the southern hemisphere using longlines. The effect of longline mortality on the population dynamics of the wandering albatross is estimated. An annual number of longline hooks in the southern hemisphere tuna fishery of 41.6 million is calculated as the ceiling below which the population would begin to recover. Part of these data were collected as part of ASAC project 751 (ASAC_751), 'Status and conservation of albatrosses on Macquarie Island'.