Macquarie Island

Macquarie Island (or Macca) lies in the southwest corner of the Pacific Ocean, about half-way between New Zealand and Antarctica, at 54°30S, 158°57E. Politically, it has formed part of the Australian state of Tasmania since 1900 and became a Tasmanian State Reserve in 1978. In 1997 it became a world heritage site. It was a part of Esperance Municipality until 1993, when the municipality was merged with other municipalities to Huon Valley. Ecologically, it is part of the Antipodes Subantarctic Islands tundra ecoregion.
 
Since 1948 the Australian Antarctic Division (AAD) has maintained a permanent base, the Macquarie Island Station, on the isthmus at the northern end of the island at the foot of Wireless Hill. The population of the base, the island's only human inhabitants, usually varies from 20 to 40 people over the year.

History



The Australian/Briton Frederick Hasselborough discovered the island accidentally in July 1810 when looking for new sealing grounds. He claimed Macquarie Island for Britain and annexed it to the colony of New South Wales in 1810. The island took its name after Colonel Lachlan Macquarie, Governor of New South Wales from 1810 to 1821. Fabian Gottlieb von Bellingshausen, who explored the area for Alexander I of Russia, produced the first map of Macquarie Island. Bellingshausen landed on the island on 28 November 1820, defined its geographical position and traded his rum and food for Macquarie Island's fauna with the sealers. Between 1810 to 1919, seals and then penguins were hunted almost to the point of extinction.

In 1890, New South Wales transferred the island to Tasmania, which leased it to Joseph Hatch (1837–1928) between 1902 and 1920 for his oil industry based on harvesting penguins.


Between 1911 and 1914, the island became a base for the Australasian Antarctic Expedition under Sir Douglas Mawson. George Ainsworth operated a meteorological station between 1911 and 1913, followed by Harold Power (1913 to 1914) and by Arthur Tulloch from 1914 until its shutdown in 1915. In 1933, the authorities declared the island a wildlife sanctuary under the Tasmanian Animals and Birds Protection Act 1928 and in 1972 it was made a State Reserve under the Tasmanian National Parks and Wildlife Act 1970. The Australian National Antarctic Research Expeditions (ANARE) established its expedition headquarters on 25 May 1948 on Macquarie Island.

On 5 December 1997, Macquarie Island was listed as a World Heritage Site mainly because of its unique geological values.


On 23 December 2004, an earthquake measuring 8.1 on the Richter magnitude scale (one of the largest earthquakes ever recorded) rocked the island, but caused little damage.

On 12 April 2008, a 7.1 earthquake on the Macquarie Fault occurred near Macquarie Island.

Geography and climate


Macquarie Island is an exposed portion of the Macquarie Ridge, and is located where the Australian plate meets the Pacific plate. It is the only place in the world where rocks from the mantle are actively exposed at sea level. Due to this it was made a UNESCO world heritage site in 1997.

The island has an approximate length of 34 km (21 mi) and a width of 5 km (3 mi), with an area of 128 km² (49 sq mi). Near Macquarie Island are two small groups of minor islands, the Judge and Clerk Islets,14 km (9 mi) to the north, and 0.2 km² (49 acres) in area, and the Bishop and Clerk Islets, 34 km (21 mi) to the south, and 0.6 km² (150 acres) in area.


The island is in two main pieces of plateau of around 150–200 m (490–660 ft) elevation to north and south, joined by a narrow isthmus close to sea level. The high points include Mount Elder on the north-east coastal ridge at 385 m (1,263 ft), and Mounts Hamilton and Fletcher in the south at 410 m (1,350 ft).

Macquarie Island lies atop a geographic feature named for the island, the Macquarie Ridge. This seafloor ridge is aligned along the eastern margin of the tectonic plate boundary between the Indo-Australian Plate and the Pacific Plate. The Bishop and Clerk Islets mark the southernmost point of Australia (including islands). In the 19th Century the phantom Emerald Island supposedly lay to the south of Macquarie Island.


Macquarie Island's climate is moderated by the sea, and all months have an average temperature above freezing, although snow is common between June and October and may even occur in Macquarie Island's "summer".

Average daily temperatures range from 3.2 °C (37.8 °F) in June and July to 7 °C (45 °F) in January. Precipitation occurs fairly evenly throughout the year and averages 917 mm (36.1 in) annually. Macquarie Island is one of the most cloudy places on earth.

                                                                 

Flora and fauna

The flora has taxonomic affinities with other subantarctic islands, especially those to the south of New Zealand. Plants rarely grow over 1 m in height, though the tussock-forming grass Poa foliosa can grow up to 2 m tall in sheltered areas. There are over 45 vascular plant species and more than 90 moss species, as well as many liverworts and lichens. Woody plants are absent. The island has five principal vegetation formations: grassland, herbfield, fen, bog and feldmark. Bog communities include 'featherbed', a deep and spongy peat bog vegetated by grasses and low herbs, with patches of free water. Endemic flora include the cushion plant Azorella macquariensis, the grass Puccinellia macquariensis, as well as two orchids - Nematoceras dienemum and Nematoceras sulcatum.

Fauna found on the island include: Subantarctic Fur Seals, Antarctic Fur Seals, New Zealand Fur Seals and Southern Elephant Seals - over 80,000 individuals of this species. Royal Penguins and Macquarie Shags are endemic breeders, while King Penguins, Southern Rockhopper Penguins and Gentoo Penguins also breed here in large numbers.

Ecological balance

The ecology of the island was affected soon after the beginning of European visits to the island in 1810. The island's fur seals, elephant seals and penguins were killed for fur and blubber. Rats and mice that were inadvertently introduced from the ships prospered due to lack of predators. Cats were subsequently introduced deliberately to keep the rodents from eating human food stores. In about 1870, rabbits were left on the island by sealers to breed for food. By the 1970s, the then 130,000 rabbits were causing tremendous damage to vegetation.

The feral cats introduced to the island have had a devastating effect on the native seabird population, with an estimated 60,000 seabird deaths per year. From 1985, efforts were undertaken to remove the cats. In June 2000, the last of the nearly 2500 cats were culled in an effort to save the seabirds. Seabird populations responded rapidly, but rats and rabbits continued to cause widespread environmental damage.
                                                                           

The rabbits rapidly multiplied before numbers were reduced to about 10,000 in the early 1980s when myxomatosis was introduced. Rabbit numbers have grown again to around 100,000 on the island. The rodents feed on young chicks while rabbits nibbling on the grass layer has led to soil erosion and cliff collapses, destroying seabird nests. Large portions of the Macquarie Island bluffs are eroding as a result. In September 2006 a large landslip at Lusitania Bay, on the eastern side of the island, partially destroyed an important penguin breeding colony. Tasmania Parks and Wildlife Service attributed the landslip to a combination of heavy spring rains and severe erosion caused by rabbits.

Research by Australian Antarctic Division scientists, published in 13 January 2009 edition of the British Ecological Society's Journal of Applied Ecology, suggested that the success of the feral cat eradication program has allowed the rabbit population to increase, damaging the Macquarie Island ecosystem by altering significant areas of island vegetation. In a later issue of the same journal however, other scientists argued that a number of factors were almost certainly involved and the absence of cats may have been relatively minor among them.


On 4 June 2007 a media release by the Australian Federal Minister for the Environment and Water Resources, Malcolm Turnbull, announced that the Australian and Tasmanian Governments had reached an agreement to jointly fund the eradication of rodent pests, including rabbits, to protect Macquarie Island's World Heritage values. The plan, estimated to cost $24 million Australian dollars, will involve mass baiting the island similar to an eradication program on New Zealand's Campbell Island, which will be followed up with dog hunting teams and is expected to take up to seven years.