Great Barrier Reef

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Great Barrier Reef
UNESCO world heritage UNESCO World Heritage Emblem

Satellite image
National territory: AustraliaAustralia Australia
Type: nature
Criteria : (vii) (viii) (ix) (x)
Surface: 34,870,000 ha
Reference No .: 154
UNESCO region : Asia and Pacific
History of enrollment
Enrollment: 1981  ( session 5 )

The Great Barrier Reef (literally translated: (Large) Barrier Reef , Great Barrier Reef or Great Barrier Reef) off the northeast coast of Australia is the largest contiguous collection of over 2,900 individual coral reefs on earth . In 1981 it was declared a World Heritage Site by UNESCO and is also referred to as one of the seven natural wonders of the world .

The Great Barrier Reef stretches northeast on the east coast of the state of Queensland in the Coral Sea from Torres Strait to Lady Elliot Island , which is about 75 kilometers northeast of Bundaberg . In the course of its evolution it has grown to a length of a good 2,300 kilometers and thus reaches an extent from the 10th to the 24th southern latitude . The crew of the HMS Endeavor under the command of the British navigator James Cook was the first European to see the Great Barrier Reef when he sailed from Botany Bay with his ship along the east coast of Australia during his first voyage to the South Sea (1768–1771) of the Cape Tribulation ran aground on June 11, 1770.

The reef runs along the eastern edge of the Australian continental shelf . It lies between 30 kilometers (near Cairns ) and around 250 kilometers (near Gladstone ) from the almost parallel east coast of Australia. There are around 1,000 islands in the waters of the Great Barrier Reef , such as B. the Whitsunday Islands or the Dunk Island , and numerous sandbanks . The area of ​​the Great Barrier Reef is approximately 347,800 km² and can be seen with the naked eye from space.


The reef lies entirely in the tropics and in the catchment area of ​​South Pacific cyclones . The cyclone season lasts from October to March, and autumn (February / March) is particularly rainy. The monthly rainfall then ranges from 215 mm in Rockhampton in the south of the reef to 350 mm in Mackay and Townsville to 525 mm in Cairns and on the Cape York Peninsula . It is dry in this area between March and October.


Satellite photo, north is on the right of the image
Helicopter image of the seabed of the Great Barrier Reef
Coral stick with a blue starfish ( Linckia laevigata )

The origin of the Great Barrier Reef goes back around 600,000 years. Overall, it is not a closed reef system, but is made up of a large number of different types of individual reefs with different origins.

The northern section of the Great Barrier Reef, which extends from the Torres Strait to approximately Cooktown, was only formed after the northern tip of Australia moved into tropical latitudes about 15 million years ago as a result of continental drift . Only the prevailing conditions there and the higher water temperature made it possible for reef-forming hard coral polyps to settle on the continental shelf near the coast. The reef formation by the calcareous hard corals was not a continuous process. As a result of the ice ages and the associated drop in sea ​​level, the populated areas dried out several times and the living coral polyps died. All that remained behind were elevations made up of coastal limestones that had formed over time through sedimentation . During the equally regularly recurring floods - caused by the ice melts that followed each Ice Age - the corals settled on the remaining sedimentary rock again and again and created further limestone mountains, which each served as a foundation for the subsequent generation.

As a result of these processes, a relatively coherent formation of coral reefs emerged in the northern part of the reef, which essentially consists of reefs of the barrier reef type . Due to the continuous lowering of the seabed and the rise in sea level, this reef barrier on the continental shelf grows seaward. On the coast side, the reef is separated from the mainland by a wide lagoon between 50 and 100 meters deep, interspersed with smaller reefs and coral banks . On the side facing away from the mainland - the Outer Reef - the barrier reef, or the continental slope on which the reef is located, slopes steeply down to a depth of 2,000 meters to the sea floor.

The central and southern parts of the reef were created later. The individual barrier reefs are arranged there in much less compact formations. In this section of the reef, fringing reefs have increasingly formed, which are very similar to the barrier reefs and also predominantly spread out towards the sea. However, they do not grow on the edge of the continental shelf, but in direct proximity to the coast and usually only have a lagoon a few meters deep towards the mainland, which was created by erosion.

Large areas of the reef used to belong to the mainland and were also flooded by the rising sea level. Most of the islands belonging to the reef are the tops of sunken mountains. They come from a coastal mountain range that was separated from the mainland during the last ice age. In contrast to real coral islands, they consist of solid rock and are mostly surrounded by a narrow fringing reef that grows directly on their banks.

Platform reefs of various sizes have formed on the flat heights of the sunken areas - which are now also included in the continental shelf . They originated on those areas where the seabed reached so far below sea level that the incidence of light was strong enough to allow corals to settle. Some platform reefs now reach a diameter of up to 15 kilometers.

The visible parts of the colorful coral reefs come from the last glacial period , about 10,000 years ago. From this point on, the different types of corals were able to settle again on the remaining limestones and become a uniquely diverse habitat for countless animal species and plants. The reef will continue to change both its appearance and its size in the future.


Antennae lionfish from the scorpion fish family - one of the reef inhabitants
The copper striped tweezer fish from the butterfly fish family can be found in shallow lagoons with dense coral growth.

Flora and fauna

The Great Barrier Reef, with its 359 species of hard coral, is the largest structure created by living things on earth. It provides habitat for a large number of other species ; 80 species of soft corals and sea ​​feathers , over 1,500 species of fish , 1,500 species of sponge , 5,000 species of molluscs , 800 species of echinoderms such as starfish, 500 different species of seaweed and 215 species of birds are native there.

Six of the seven species of sea ​​turtles found worldwide are found in the Great Barrier Reef . Among them are the endangered caretta-caretta turtles and the Pacific green turtles that use the reef to lay their eggs. The dugongs ( manatees ) living there are also threatened with extinction . In addition, the humpback whales that live near the Antarctic use the warm waters to give birth to their young , along with other whale species that occur there .

The jagged and ramified coral sticks provide ideal conditions for snails and rare mussels, such as Arthritica species or spiny snails , such as Murex pecten .


Coral reefs are very sensitive ecosystems. Any change can cause unpredictable damage.

Corals can only thrive and survive in clear, sun-drenched water with a very limited temperature range, between around 18 and 30 degrees Celsius. An increase in the water temperature leads to the repulsion and subsequent death of the zooxanthellae , the vital algae growth of the corals. Since these algae are not only responsible for the symbiotic supply of nutrients but also for the coloring of the coral, the coral stock fades and the white limestone structure becomes visible. If this condition persists over a longer period of time because the algae cannot grow back due to constant water heating, the corals will die from a lack of nutrients.

The global public was alarmed when on April 3, 2010 the Chinese bulk carrier MS Shen Neng 1 ran aground on the Great Barrier Reef with a cargo of 65,000 tons of coal and 950 tons of oil on board. On April 4, 2010, four tons of oil leaked, but it could be broken down with a chemical. Although an oil spill was prevented from affecting the ecosystem, a small area of ​​the reef was destroyed when the ship ran aground. According to press reports, 250 by 100 meters to 3 kilometers by 250 meters were destroyed.

Propagation of the corals

Green turtle ( Chelonia mydas )

The annual colorful coral bloom, which is used to multiply corals, is a special event. This takes place on the Great Barrier Reef during the Australian spring in November and is based on a schedule strictly prescribed by nature. The factors influencing the time are the water temperature of around 27 ° C, the length of the day and the phase of the moon. Only a meticulously coordinated ejection of large quantities of egg cells and semen ensures successful reproduction of the animals under the difficult conditions caused by predators and strong ocean currents.


In 2018, the national park administration counted 2.28 million tourist days. In 2003 they spent over 4 billion Australian dollars . Marine tourism is correspondingly important for northern Queensland. There are approximately 820 reef tour operators who provide approximately 1,500 boats, helicopters and small planes for tours to the reef. They operate out of the coastal cities, with 85 percent of tourism being concentrated in the two cities of Cairns and Airlie Beach .

In the cities, companies offer excursions, from day trips to sailing trips lasting several weeks. The vehicle size ranges from small sailing boats to large catamarans with over 400 seats. Around 40 percent of the tourism business is in the hands of the ten largest providers.

You can marvel at the reef on dry feet by taking a trip in a glass-bottom boat or a semi-submarine, as well as by visiting one of the countless underwater observatories . However, the most popular type of reef experience is snorkeling or diving .

Ideal areas for diving and snorkeling are on the outer belt of the reef, the Outer Barrier. Thanks to the proximity to the open sea, the underwater visibility is increased, as fewer sediments can be deposited in the water. Especially for mass tourism and novice divers, pontoons have been firmly anchored in the outer reef, which are approached by ships. The surrounding areas are often demarcated with nets to protect divers and snorkelers from attacks by reef sharks . Experienced divers use liveaboard boats, most of which depart from Cairns or Port Douglas , to dive at remote reef sites .

World heritage and protection measures

A broad public movement developed in Australia in the early 1970s to protect the Great Barrier Reef from oil drilling and underwater mining. This led to the creation of the Great Barrier Reef Marine Park in 1975, covering an area of ​​343,966 km²

Due to its dimensions, the Marine Nature Park is divided into several sections for better differentiation. These are from north to south:

  • Far Northern Section
  • Northern Section
  • Cairns Section (also Tropical Northern )
  • Central Section (also Whitsunday Section )
  • Southern Section (also Mackay Capricorn Reefs ).

On October 26, 1981, the reef system was declared a World Heritage Site by UNESCO. It met all four of the criteria at the time.

Protective measures can only partly be implemented at short notice due to the many causes. Much of the man-made environmental pollution comes from the remodeling of the original natural region of the Cape York Peninsula . On the one hand, this concerns the high levels of nutrients and suspended matter due to intensive agriculture in the hinterland of the coastal region, and on the other hand, due to the construction of settlements and their associated infrastructure , such as roads, ports or industrial plants. In general, around 14 million tons of soil are assumed to erode in the hinterland every year, which corresponds to a natural rate of erosion five times higher and is carried into the sea via the numerous river systems such as the Fitzroy River . Every year around 66,000 tonnes of nitrogen, 14,000 tonnes of phosphorus compounds and around 28 tonnes of herbicides from the arable land enter the marine region of the Great Barrier Reef in this way. These additional abiotic environmental stress factors lead to a weakening of the resistance of the corals and, together with other environmental stress factors, lead to the outbreak of the so-called coral disease . The coral disease was responsible for around 6.5 percent of all dead corals between 1995 and 2009.

Further pollutants get into the sea water as a result of the increased development of some islands and the tourist use of the reef. All in all, fuel and anchoring from boats, sun oil from snorkelers and collecting souvenirs are just as bad for the ecosystem as inconsiderate divers who do not recognize the sensitivity of the reef and thus its destructive effect. Also the consideration of drilling for oil in the approximately 200,000 km² area threatens the reef. Against overfishing and the destruction of reefs by trawl action has been taken. But despite the bans, it will take years for the imbalanced ecosystem to recover.

To protect the world heritage, a comprehensive 25-year strategic plan was drawn up with the aim of intensively researching the endangered ecosystem and bringing it back into balance - also or precisely because the Great Barrier Reef, in contrast to many other coral reefs that are in danger of dying off , is still in relatively good condition. The wreck of the passenger ship SS Yongala , which sank on March 23, 1911 and was rediscovered in 1958, is very popular with divers and a valuable protected area. The same applies to the wrecks of the SS Gothenburg , the RMS Quetta and numerous others. At that time, the first extensive inventory was already carried out, the data of which has become particularly valuable because it enables long-term results.

The World Heritage Committee reacted critically to plans to economically expand the Australian coasts behind the reef. In particular, the proposed port of Abbot Point for the export of coal and liquefied natural gas met with concern. In 2014, the committee expressed its concern, but postponed a decision to put the reef on the World Heritage List in Danger for a year. By 2015, the Australian government should then provide further data on the planning and measures to protect the reef. In 2016, UNESCO published a report on the threat posed to various world cultural sites by global warming . Following the intervention of the Australian government, which feared a decline in tourism, all passages to Australian sites were removed from the report, including those to the Great Barrier Reef. This cut, perceived as censorship , attracted considerable public attention and aroused strong criticism of the Australian government as well as UNESCO.

Damage and endangerment

The existence of the Great Barrier Reef and its great biodiversity is seriously threatened by the anthropogenic greenhouse effect and the associated changes in the chemistry of the oceans : Between 1985 and 2012, the coral cover decreased from 28 to 13.8 percent; a further decline to five to ten percent within ten years is likely due to greenhouse gas emissions . If coral reefs like the Great Barrier Reef are to continue to exist in the future, climate protection measures that are effective very quickly are necessary to combat global warming quickly .

At the end of August 2019, Australia downgraded the perspective of the Great Barrier Reef to its lowest level - from “bad” to “very bad”.

Global warming (coral bleaching)

Between 1985 and 2012 the reef lost half of its coral. As a result of global warming and the associated warming of the oceans , the Great Barrier Reef was severely affected by mass coral bleaching in 1998 and 2002 and especially in 2016 ; In 2002, 60 to 95 percent of the reef was damaged. Most of it has recovered - however, 5% of the reef has been so badly destroyed that it will take several years to decades for the reef to fully recover from the damage.

Another problem caused by global warming is cyclones , which have increased in intensity and can destroy large areas with their waves. The acidification of the oceans through the uptake of carbon dioxide has been shown to reduce the growth rate of hard corals.

According to a report by James Cook University from May 2016, as a result of coral bleaching in 2016, 35% of the corals of the Great Barrier Reef have almost or completely died. Coral bleaching occurred again in 2017, this time mainly in the middle section. It was the first time that two coral bleaching occurred directly in two consecutive years, moreover, the bleaching of 2017 was not caused by an El Niño. During the two bleaches in 2016 and 2017, around half of the corals still present on the reef died. In 2018 - compared to years of normal growth - an 89 percent decline in coral larvae was noted. In the Australian summer of 2019/20, there was another very extensive bleaching, which now also affected the southern parts of the reef, which had been spared during the previous bleaching. Overall, coral bleaching of the same size occurred in the Great Barrier Reef within five years.

April 2020 reported the most extensive bleaching in the Great Barrier Reef in the past five years.

Endangerment from the coal industry

In December 2013, the conservative Australian government under Tony Abbott approved the expansion of the Abbot Point coal port on the Great Barrier Reef to become the world's largest coal port. For this purpose, three million cubic meters of sludge are to be excavated by a company of the Adani Group and disposed of in the sea. Environmentalists fear massive damage from the mud in the reef. Coal deposits from the Galilee Basin in Queensland ( Carmichael coal mine ) with an estimated market value of 28 billion US dollars are to be developed via the port . The German bank announced at its General Assembly in May 2014 that it had dropped the intention to participate in the financing of the port. The KfW -Bank promotes the export of German technology for the expansion of another port (coal port Wiggins Iceland) with a total of 110 million euros .

For decades, tipping dredged material into the sea was the norm. It was only in November 2015 that the Queensland Parliament issued a corresponding ban across the Great Barrier Reef to end the destructive practice. However, in May 2016, Australian Environment Minister Greg Hunt denied that coal mining and burning had a "significant" impact on climate change and national ecosystems.

Natural factors

A natural and destructive enemy is the poisonous crown of thorns starfish . It occurs massively at time intervals and then disappears again. Its as yet unexplored occurrence leaves completely dead reef sections, as it sucks the living coral polyps out of their protective limestone shells and eats them up.



  • Great Barrier Reef. (OT: Great Barrier Reef. ) Episode 1: Natural wonders of superlatives. Documentary, Great Britain, Australia, 2011, 43 min., Book: James Brickell, Richard Fitzpatrick, director: James Brickell, production: BBC Earth, Digital Dimensions, Discovery Channel , Nine Network Australia, Polyband, German first broadcast: June 4, 2012 on ARD , film information ( memento from February 11, 2013 in the web archive ) from ARD, preview .
  • Great Barrier Reef. Episode 2: From the reef to the rainforest. Documentary, Great Britain, Australia, 2011, 43 min., Book: James Brickell, Richard Fitzpatrick, director: James Brickell, production: BBC Earth, Digital Dimensions, Discovery Channel , Nine Network Australia, German first broadcast: June 11, 2012 on ARD , Film information ( memento of November 3, 2012 in the Internet Archive ) from ARD.
  • Great Barrier Reef. Episode 3: Animal visitors from all over the world. Documentary, Great Britain, Australia, 2011, 43 min., Book: James Brickell, Richard Fitzpatrick, director: James Brickell, production: BBC Earth, Digital Dimensions, Discovery Channel, Nine Network Australia, film information from BBC Germany.
  • Australia's Great Barrier Reef. Documentary, Germany, 2003, 43 min., Script and director: Dirk Steffens , production:, ZDF , film information from Phoenix .
  • Australia: Great Barrier Reef in danger. Documentation ( Weltspiegel contribution), Germany, 2014, 11:17 min., Author: Norbert Lübbers , production: Bayerisches Fernsehen , film information from ARD .

Web links

Commons : Great Barrier Reef  - Collection of Images, Videos and Audio Files

Individual evidence

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Coordinates: 19 °  S , 149 °  E