7 Natural Wonders of the World

Great Barrier Reef
Queensland, Australia
7 Natural Wonders of the World
Individual reefs-2,900
Islands in reef-over 900
Total area-3,000 kilometres (1,600 mi) over an area of approximately 344,400 square kilometres (133,000 sq mi).
	Heron Island [1]

 

	The Great Barrier Reef reaches from Torres Strait (between Bramble Cay, its northernmost island, and the south coast of Papua New Guinea) in the north to the unnamed passage between Lady Elliot Island (its southernmost island) and Fraser Island in the south. Lady Elliot Island is located 1,915 km (1,190 mi) southeast of Bramble Cay as the crow flies
Great Barrier Reef [2]

 

The Great Barrier Reef, the world's largest coral reef system, comprises roughly three thousand individual reefs and nine hundred islands stretching for 1,616 miles (2,586 kilometers) and covering an area of approximately 214,000 square miles (554,260 square kilometers). The reef is located in the Coral Sea, off the coast of Queensland in northeast Australia. A large part of the reef is protected by the Great Barrier Reef Marine Park Authority (GBRMPA).

The Great Barrier Reef can be seen from space and is sometimes referred to as the single largest organism in the world. In reality, it is a complex ecosystem comprising many billions of tiny organisms, known as coral polyps, living in harmony with countless species of rare and exquisite flora and fauna. The reef was also selected as a UNESCO World Heritage Site in 1981, and it has been labeled as one of the seven natural wonders of the world. The Queensland National Trust has named it a state icon of Queensland. Each year, some 2 million tourists from around the world come to swim, fish, and enjoy the magnificent ecosystem of the Great Barrier Reef.

For all its complexity, variety, and history, it is a remarkably fragile environment. In recent years, concern has grown that climate change associated with global warming and harmful influences of human use have become a serious and compounding threats to the reef. Both the living coral and the wondrous other creatures who occupy the reef are in jeopardy.

According to the Great Barrier Reef Marine Park Authority, the current living reef structure is believed to have begun growing on an older platform about twenty thousand years ago when the sea level was about 130 meters (426 feet) lower than it is today. The Reef Research Centre, a Cooperative Research Centre, has found coral 'skeleton' deposits that date back half a million years.

From 20,000 years ago until 6,000 years ago, the sea level rose steadily. By around 13,000 years ago, the rising sea level was within 60 meters (196 feet) of its present level, and coral began to grow around the hills of the coastal plain, which by then were continental islands. As the sea level rose further still, most of the continental islands were submerged and the coral could then overgrow the hills, to form the present cays and reefs. Sea level on the Great Barrier Reef has not risen significantly in the last 6,000 years.

In the northern part of the Great Barrier Reef, ribbon reefs&mdash:long and thin and lacking a lagoon—and deltaic reefs resembling a river delta have formed; these reef structures are not found in the rest of the Great Barrier Reef system

Species of the Great Barrier Reef
The Great Barrier Reef supports a variety of life, including many vulnerable or endangered species. Thirty species of whales, dolphins, and other porpoises have been recorded in the reef, including the dwarf minke whale, the Indo-Pacific humpback dolphin, and the humpback whale. Also, large populations of dugongs (herbivorous marine mammals similar to manatees) live there. Six species of sea turtle come to the reef to breed—green sea turtle, leatherback sea turtle, hawksbill turtle, loggerhead sea turtle, flatback turtle, and the olive ridley. The dugongs and sea turtles are attracted by the reef's 15 species of seagrass.

More than two hundred species of birds (including 40 species of water birds) live on the Great Barrier Reef, including the white-bellied sea eagle and roseate tern. Some five thousand species of mollusk have been recorded there, including the giant clam and various nudibranches and cone snails, as well as 17 species of sea snake. More than fifteen hundred species of fish live on the reef, including the clownfish, red bass, red-throat emperor, and several species of snapper and coral trout. Four hundred species of coral, both hard coral and soft coral, are found on the reef. Five hundred species of marine algae or seaweed live on the reef, along with the Irukandji jellyfish.[3]