Satellite image of a part of the Great Barrier Reef. Photo courtesy of NASA.

The Great Barrier Reef is the world's largest coral reef. The reef is located in the Coral Sea off the coast of Australia. It stretches over 2000 kilometres in length and can be seen from space.

The first European explorer to see the Great Barrier Reef was Captain James Cook during his 1768 voyage. Cook discovered the reef by running aground on it June 11th 1770.

Due to its vast biodiversity, warm clear waters and its accessibility from the floating guest facilities called 'live aboards', the Reef is a very popular destination for scuba divers. Many cities along the Queensland coast offer boat trips to the reef on a daily basis. Several continental islands have been turned into resorts.

The Great Barrier Reef is sometimes referred to as the single largest living animal being in the world. In reality it is many colonies of corals.

A large part of the reef is protected by the Great Barrier Reef Marine Park.

Environmental threats

The most significant threat to the future of the Great Barrier Reef and of the planet's other tropical reef ecosystems is global warming. Many of the corals of the Great Barrier Reef are currently living at the upper edge of their temperature tolerance, as demonstrated in the coral bleaching events of the summers of 1998 and 2002. Under the stress of waters that remain too warm for too long, corals expel their photosynthesizing zooanthellae and turn colourless, revealing their white skeletons, and soon die. Global warming has triggered the collapse of reef ecosystems throughout the tropics. Increased global temperatures bring more violent tropical storms, but reef systems are naturally resilient and recover from storm battering.

In recent years, run-off from agriculture, especially sugarcane fields, has had a significant impact. Increased silting and coral bleaching have killed large areas of the reef. It is unknown what effect the recent near collapse of the Australian sugar industry will have.

Crown-of-Thorns starfish are predators of corals. When the reef system is out of balance, Crown-of-thorns populations can explode. Several popular areas of the reef have been severely damaged by Crown-of-thorn attacks in recent decades.

The sheer number of visitors to the reef is itself a problem. Popular areas like Green Island have suffered considerable damage from tourists.

On July 1, 2004 the reef became the largest sea reserve in the world when the Australian Environment Ministry increased the protected area from 4.5% to 33.3%. It was inscribed as a World Heritage site in 1981.

External Links

• Official site of the Great Barrier Reef Marine Park (http://www.gbrmpa.gov.au/)
• Photos of the Great Barrier Reef _ Terra Galleria (http://www.terragalleria.com/pacific/australia/great_barrier_reef)
• Australia Underwater (http://www.underwater.com.au/) _ All about diving in Australia _ includes photo gallery from all around Australia.