The Great Barrier Reef is in the sea in Australia.
It is made of coral.
The coral stretches for 2,000 kilometres.
The coral is made by tiny animals called polyps.
The Barrier Reef is home to many sea creatures.
How big is the Great Barrier Reef?
The Great Barrier Reef is the largest coral reef in the world. It is 2, 000 kilometres long, and is 180 metres high in some places. It can can be seen from outer space, and is considered to be one of the seven Natural Wonders of the World.
What is the Great Barrier Reef and where is it?
The Great Barrier Reef is not in fact one single reef, but a system of about 3, 000 individual coral reefs and islands stretching from Cape York to Gladstone off the Queensland coast. Coral reefs are also found in other warm Australian waters.
Life on the Great Barrier Reef
The Great Barrier Reef has been built over many millions of years by tiny animals called polyps. The Reef is home to a huge variety of fish and other sea creatures. Scientists have recorded more than 1,500 species (kinds) of fish living in the Great Barrier Reef.
The Barrier Reef is Protected
The Great Barrier Reef was declared a marine park in 1976, and was listed as a World Heritage site in 1981.
A Living Thing
Like any coral reef, the Great Barrier Reef can be killed because it is made up of living creatures.
Threats to the Great Barrier Reef
Ships running aground on the reef or oil spills can destroy large sections of the reef. The quickest way for ships to take Australian coal to China and India is from ports along the Reef. The sea is too shallow there for the big container ships, so there has been a threat of dredging to make the sea deeper for the ships to go in and out of those ports. There is great fear and alarm that the resulting silt could choke corals and sea grasses and kill them.
Tourism and Development
Development, building, and mining are killing the reef. When the sea is polluted by rubbish and soil is washed into it by excavation of and building on the land near the reef, the coral is affected because it can only grow in clear water.
Tourism means a lot of boating in the Reef, for people to see it, and to dive from the boats. Sightseers walking on the reef kills coral.
The crown-of-thorns starfish eats coral polyps. This starfish has always been part of life in a coral reef, but the balance has been tipped because the main natural predator of the starfish, the triton, is greatly prized by humans for its shell. This has resulted in a drop in triton numbers, an increase in the number of starfish and the destruction of very large areas of coral.
When corals are stressed by changes in conditions such as temperature, light, or nutrients, (food supply) they expel the symbiotic algae living in their tissues, causing them to turn completely white. Coral bleaching can cause coral to die. There has been extensive coral bleaching on parts of the great Barrier Reef on many occasions: 1998, 2002 and in 2016.