Part of the Great Barrier Reef seen from the air. ©Getty Images

Part of the Great Barrier Reef seen from the air. ©Getty Images

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.

Some coral formations in the Great Barrier Reef ©Getty Images

Some coral formations in the Great Barrier Reef ©Getty Images

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

There is a threat to dredge near the Reef to make the sea deep enough for big ships ©Getty Images

There is a threat to dredge near the Reef to make the sea deep enough for big ships ©Getty Images

Shipping

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

Tourism boat on the Reef ©Getty Images

Tourism boat on the Reef ©Getty Images

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.

Crown-of-thorns starfish

The crown of thorns starfish .

The crown of thorns starfish .

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.

Coral bleaching

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.

http://www.gbrmpa.gov.au/managing-the-reef/threats-to-the-reef/climate-change/what-does-this-mean-for-species/corals/what-is-coral-bleaching

Read some facts about the Great Barrier Reef. Click on the tab 'Looking after the Reef' to find out more.

Click on the link at the bottom to find out about the fish of the Great Barrier Reef

Read the kidcyber page about how coral is formed and how it grows

Watch a video about animals of the Reef:  Exploring Oceans: Great Barrier Reef

More geography games on oceans at NeoK12