Michaelmas Cay Bird Sanctuary : 無料・フリー素材/写真
Michaelmas Cay Bird Sanctuary / wallygrom
| ライセンス | クリエイティブ・コモンズ 表示-継承 2.1 |
|---|---|
| 説明 | Michaelmas Cay, Queensland, Australia.On board the catamaran Ocean Spirit heading for the Great Barrier Reef at Michaelmas Cay.Michaelmas Reef forms the north-east section of the Arlington reef complex, which sits atop a platform reaching approximately 30 metres below sea level.Michaelmas Cay is a leeside sand cay, orientated north-east to south-west, on the western tip of Michaelmas Reef. It was formed by the accumulation of broken coral, shells and remains of calcareous algae, continually being washed over the reef by currents. Over time, seeds were deposited by visiting birds and the resulting vegetation helped to stabilise the cay. The formation of beach rock—sand and other reef remnants cemented into a rock by the action of algae—has further stabilised the cay.In 1926 Great Barrier Reef Committee geologists drilled a bore hole on Michaelmas Cay to 182.8 metres. This revealed a sequence of reef rock extending to 115.3 metres, underlain by quartz sand. The cay continues to build up and erode depending on wind, sea conditions and currents, with mobile spits at either end of the cay. Michaelmas Cay is reportedly moving about one metre north every year.Although Upolu Cay was formed the same way, it is not stabilised by vegetation or beach rock and so is more dynamic in shape, size and position.PlantsThe vegetation on Michaelmas Cay is more characteristic of the cays found on the outer barrier reef. It is low-growing and composed of beach spinifex (Spinifex sericeus), stalky grass (Lepturus repens), goats foot (Ipomoea pes-caprae), bulls head vine (Tribulus cistoides), sea purslane (Sesuvium portulacastrum) and tar vine (Boerhavia diffusa). Nutrients from seabird droppings and carcasses assist in fertilising the vegetation. Occasionally seeds from trees such as Barringtonia sp. and mangroves wash ashore and germinate but die due to a lack of suitable stable substrate. There are no known introduced plants on Michaelmas Cay.In contrast to Michaelmas Cay, Upolu Cay is unvegetated. AnimalsAt least 14 species of seabirds have been recorded on Michaelmas Cay. Of the 22 species of seabirds recorded breeding within the Great Barrier Reef Marine Park, at least four regularly breed on the cay—common noddies (Anous stolidus), sooty terns (Onychoprion fuscata), crested terns (Thalasseus bergii) and lesser crested terns (Thalasseus bengalensis). Other species recorded include the endangered little terns (Sternula albifrons), brown boobies (Sula leucogaster), lesser frigatebirds (Fregata ariel), ruddy turnstone (Arenaria interpres), silver gull (Chroicocephalus novaehollandiae), bridled terns (Onychoprion anaethetus), black-naped terns (Sterna sumatrana), eastern reef egrets (Egretta sacra) and roseate terns (Sterna dougallii).. Nesting peaks in summer when more than 20,000 pairs of seabirds have been observed.Detailed seabird research has been conducted monthly since 1984 by QPWS. Information includes details on species, numbers present, breeding, size class and vegetation cover. It has been found that populations of seabirds breeding on the cay have declined in recent years. Along with human disturbance and reduction in food availablity, the seabirds also face natural threats such as cyclones, strong gales and erosion of their nesting sites. Seabirds have also been identified as highly vulnerable to climate change.Seabirds commonly roost on Upolu Cay and although there has been past evidence of nesting by black-naped terns (Sterna sumatrana), common noddys (Anous stolidus) and crested terns (Thalasseus bergii), there has been no formal record of breeding. The reduction of the size of the cay following cyclones and storms negatively affects breeding as nesting sites are inundated during high tides.Since 1986 the Australian Institute of Marine Science has surveyed Michaelmas Reef annually. Monitoring programs have shown an apparent decline in the levels of coral cover. Crown of thorns starfish outbreaks have been recorded.Green turtles occasionally nest on the cays. Nearby reefs support a rich mollusc fauna, including populations of giant clams (Tridacna gigas).Culture and historyIndigenous culture and historyThe cays and their surrounding reefs are part of the traditional sea country historically shared between Gungandji, Mandingalbay-Yidinji and Yirriganydji people.Traditional use of the cays is recognised and continues in accordance with the provisions of current legislation regulating such activities in protected areas.European historyMichaelmas Cay was formally named Oyster Cay in 1849 when the HMS Bramble anchored offshore. The cay was used by the beche-de-mer (sea cucumber) industry from 1870 to 1900 and then a guano (seabird droppings) mining lease operated for a short time from 1901. It was declared a fauna sanctuary in 1937.Upolu Cay and reef were named after the schooner Upolu that ran aground on the reef surrounding the cay on Easter Sunday, 25 April 1886. The crew salvaged stores collected the day before from Townsville and ferried them to a sand cay three miles away, where they spent the night. The crew set sail for Port Douglas in a lifeboat on 27 March and were eventually picked up by the Bulimba off Cape Grafton on 4 May.Michaelmas Cay and Upolu Cay were declared a single national park in 1975. |
| 撮影日 | 2007-02-01 01:57:51 |
| 撮影者 | wallygrom |
| タグ | |
| 撮影地 | Queensland, Australia 地図 |
| カメラ | KODAK V610 DUAL LENS DIGITAL CAMERA , EASTMAN KODAK COMPANY |
| 露出 | 0.002 sec (1/640) |
| 開放F値 | f/7.1 |