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Tuesday, December 29, 2009

Great Barrier Reef

The Great Barrier Reef is the world's biggest coral reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,600 kilometres / 1,600 miles over an area of approximately 344,400 square kilometres / 133,000 sq miles. The reef is located in the Coral Sea, off the coast of Queensland in northeast Australia.

Great Barrier ReefThe Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organisms. This reef structure is composed of and built by billions of tiny organisms, known as coral polyps. The Great Barrier Reef supports a wide diversity of life, and was selected as a World Heritage Site in 1981. CNN has labeled it one of the 7 natural wonders of the world. The Queensland National Trust has named it a state icon of Queensland.

A large part of the reef is protected by the Great Barrier Reef Marine Park, which helps to limit the impact of human use, such as overfishing and tourism. Other environmental pressures to the reef and its ecosystem include water quality from runoff, climate change accompanied by mass coral bleaching, and cyclic outbreaks of the crown-of-thorns starfish.

The Great Barrier Reef has long been known to and utilised by the Aboriginal Australian and Torres Strait Islander people, and is an important part of local groups' cultures and spirituality. The reef is a very popular destination for tourists, especially in the Whitsundays and Cairns regions. Tourism is also an important economic activity for the region. Fishing also occurs in the region, generating Australia 1 billion dollar per year.

The Great Barrier Reef reaches from Torres Strait in the north to the unnamed passage between Lady Elliot Island and Fraser Island in the south. Lady Elliot Island is located 1,915 km / 1,190 miles southeast of Bramble Cay as the crow flies.The Great Barrier Reef supports a diversity of life, including many vulnerable or endangered species, some of which may be endemic to the reef system. Thirty species of whales, dolphins, and porpoises have been recorded in the Great Barrier Reef, including the dwarf minke whale, Indo-Pacific humpback dolphin, and the humpback whale. Large populations of dugongs live there.

Six species of sea turtles come to the reef to breed – the green sea turtle, leatherback sea turtle, hawksbill turtle, loggerhead sea turtle, flatback turtle, and the olive ridley. Fifteen species of seagrass in beds attract the dugongs and turtles, and provide a habitat for fish. The most common genera of seagrasses are Halophila and Halodule. Saltwater crocodiles live in mangrove and salt marshes on the coast near the reef. Nearly 125 species of shark, stingray, skates or chimera live on the reef.

Green Sea TurtleBlue Linckia Starfish215 species of birds including 22 species of seabirds and 32 species of shorebirds are attracted to the reef or nest or roost on the islands, including the white-bellied sea eagle and roseate tern. Most nesting sites are on islands in the northern and southern regions of the Great Barrier Reef, with 1.4-1.7 million birds using the sites to breed. Seventeen species of sea snake live on the Great Barrier Reef.

More than 1,500 species of fish live on the reef, including the clownfish, red bass, red-throat emperor, and several species of snapper and coral trout. Forty-nine species are known to mass spawn, with eighty-four other species found on the reef spawning elsewhere in their range. Four hundred species of corals, both hard corals and soft corals are found on the reef. The majority of these spawn gametes, breeding in mass spawning events that are controlled by the rising sea temperatures of spring and summer, the lunar cycle, and the diurnal cycle.

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