great barrier reef
The Great Barrier Reef is the world’s largest reef system and bar far the most beautiful. It is comprised of almost 3,000 individual reefs and 900 islands. It stretches over 1,600 miles over an area of around 133,000 square miles. The reef is located in the Coral Sea, which is off the coast of Queensland in Australia. The Great Barrier Reef can be seen from space and is the world’s biggest structure made by living organisms, including humans. These organisms are coral polyps. Boasting a diverse aquatic life, the Great Barrier Reef was selected as a World Heritage Site in 1981.
The Great Barrier Reef comprises a series of reefs extending more than 1,250 miles along the northeast coast of Australia, at an offshore distance ranging from 10 miles in the north to 100 miles in the south. So it’s total length is comparable to the entire west coast of the United States, from Washington to Southern California.
The reef and island area cover some 80,000 miles squared equalling England, Wales and Ireland combined. This area is only about one third of the expanse of the surrounding water within the Great Barrier Reef province. There are over 2,500 reefs with areas ranging from a few hundred hectares to more than 32 miles square, together with many smaller reefs. The Great Barrier Reef actually consists of many thousands of separate reefs- some mainly dry or barely awash at low tide, some with islands of coral sand (cays), and others fringing high islands or mainland coasts. The reef has risen in warm waters on the shallow shelf fringing the Australian continent. The continental shelf has a change of gradient at about 590 feet.
Each reef is formed from the skeletons of living marine organisms including calcareous remains of the green algae Halimeda and coral polyps. So prolific is the calcification of Halimeda that 5.5 inch of sediment may accumulate in 1000 years. The cement that binds these flakes together is largely manufactured by calcareous red algae called corallines, which form a carpet over the coral banks, especially in surge areas. The joint contribution of calcareous green and red algae accounts for more than half the accretion of carbonates on the Great Barrier Reef.
The first known physical encounter between Europeans and the Great Barrier Reef occurred in 1770, when Captain James Cook ran the 21-meter HMS Endeavour aground on it. The work of charting channels and passages through the maze of reefs begun by Cook, continued during the 19th Century when scientists, including the Swiss-American zoologist Alexander Agassiz, made expeditions to this newfound wonder of the world. The contribution of the Great Barrier Reef Expedition of 1928-1929 remains unsurpassed in the fields of coral ecology and physiology. A modern laboratory designed to continue reef studies was setup on Heron Island in 1951 and is run by the University of Queensland and the Great Barrier Reef Committee.