The 'Great Barrier Reef' in
Australia is the world's largest
coral reef system,
[ Protected Areas and World Heritage - Great Barrier Reef World Heritage Area UNEP World Conservation Monitoring Centre ][ Great Barrier Reef World Heritage Values ] composed of roughly 3000 individual reefs and 900 islands stretching for 2600 kilometres (1,616 mi) over an area of approximately .
[1][ Review of the Great Barrier Reef Marine Park Act 1975 Department of the Environment and Heritage ] The reef is located in the
Coral Sea, off the coast of
Queensland in northeast
Australia.
The Great Barrier Reef can be seen from
outer space and is the world's biggest single structure made by living organisms.
[2] This reef structure is composed of and built by billions of tiny organisms, known as
coral polyps.
[ Australia's Great Barrier Reef Sharon Guynup ] The Great Barrier Reef supports a wide diversity of life and was selected as a
World Heritage Site in 1981.
has labelled it one of the
seven natural wonders of the world.
[3] The Queensland National Trust has named it a state icon of Queensland.
[4]
A large part of the reef is protected by the
Great Barrier Reef Marine Park, which helps to limit the impact of human use, such as overfishing and tourism. Other environmental pressures to the reef and its ecosystem include water quality from runoff, climate change accompanied by mass coral bleaching, and cyclic outbreaks of the
crown-of-thorns starfish.
Geology and geography
Satellite image of part of the Great Barrier Reef adjacent to the Queensland coastal areas of
Proserpine and
Mackay.
The Reef Research Centre, a
Cooperative Research Centre, has found coral 'skeleton'
deposits that date back half a million years.
[ What is the Great Barrier Reef? CRC Reef Research Centre Ltd ] The Great Barrier Reef Marine Park Authority says that corals have been growing in the region for as long as 25 million years, but have not always formed coral reef structures. The GBRMPA considers the earliest evidence to suggest complete reef structures to have been 600,000 years ago.
[ A "big picture" view of the Great Barrier Reef Great Barrier Reef Marine Park Authority ]
Dating inconsistencies stem from how reefs fluctuate (grow and recede) as the
sea level changes. They can increase in diameter from 1 to 2 centimetres per year, and grow vertically anywhere from 1 to 15 centimetres (0.4–12
in) per year; however, they are limited to growing above a depth of due to their need for sunlight, and cannot grow above sea level.
[5]
According to the
Great Barrier Reef Marine Park Authority, the current, living reef structure is believed to have begun growing on an older platform about 20,000 years ago.
The
Australian Institute of Marine Science agrees, which places the beginning of the growth of the current reef at the time of the
Last Glacial Maximum. At around that time, the sea level was lower than it is today. The land that formed the of the Great Barrier Reef was a
coastal plain with some larger hills (some of which were themselves remnants of older reefs).
[ How the Great Barrier Reef was formed ]
Heron Island, a coral cay in the southern Great Barrier Reef.
From 20000 years ago until 6000 years ago, the
sea level rose steadily. As it rose, the corals could then grow higher on the hills of the coastal plain. By around 13000 years ago the sea level was lower than the present day, and corals began to grow around the hills of the coastal plain, which were, by then,
continental islands. As the sea level rose further still, most of the continental islands were submerged. The corals could then overgrow the hills, to form the present
cays and reefs. Sea level on the Great Barrier Reef has not risen significantly in the last 6,000 years.
The CRC Reef Research Centre estimates the age of the present, living reef structure at 6000 to 8000 years old.
The remains of an ancient barrier reef similar to the Great Barrier Reef can be found in
The Kimberley, a northern region of
Western Australia.
[6]
The
Great Barrier Reef World Heritage Area has been divided into 70
bioregions,
[7] of which 30 are reef bioregions,
[8] and 40 are non-reef bioregions.
[9][10] In the northern part of the Great Barrier Reef,
ribbon reefs and
deltaic reefs have formed; these structures are not found in the rest of the Great Barrier Reef system.
Ecology
The Great Barrier Reef supports a diversity of life, including many
vulnerable,
endangered species and some which may be
endemic to the Great Barrier Reef.
[11][12]
Some 30 species of whales, dolphins, and porpoises have been recorded in the Great Barrier Reef, including the
Dwarf Minke Whale,
Indo-Pacific Humpback Dolphin and the
Humpback Whale. Large populations of
dugongs live there.
[ REEF FACTS: Plants and Animals on the Great Barrier Reef CRC Reef Research Centre Ltd ][13]
Six species of
sea turtle come to the reef to breed –
Green Sea Turtle,
Leatherback Sea Turtle,
Hawksbill turtle,
Loggerhead Sea Turtle,
Flatback Turtle and the
Olive Ridley. 15 species of seagrass attract the dugongs and turtles.
The most common
genera of seagrasses are ''Halophila'' and ''Halodule''.
[14] The Green Sea Turtles on the Great Barrier Reef have two
genetically distinct populations - one in the northern Great Barrier Reef, and the other in the southern Great Barrier Reef.
[15] Salt water crocodiles live in mangrove and saltmarshes on the coast near the Great Barrier Reef.
[16]
Over 200 species of birds (including 40 species of waterbirds) live on the Great Barrier Reef, including the
White-bellied Sea Eagle and
Roseate Tern.
Most nesting sites are on islands in the northern and southern regions of the Great Barrier Reef, with 1.4-1.7 million birds using the sites to breed.
[17][18]
Around 125 species of shark, stingray, skates or chimera live on the Great Barrier Reef.
[19]The
irukandji jellyfish also lives on the reef.
Close to 5000 species of
mollusc have been recorded on the Great Barrier Reef including the
Giant Clam and various
nudibranches and
cone snails.
Seventeen species of
sea snake live on the Great Barrier Reef. They take three or four years to reach sexual maturity and are long lived but with low fertility. They are usually
benthic, but different species live on the soft sediment as compared to the reefs themselves. They live in warm waters up to deep. They are more common in the southern Great Barrier Reef than the northern Great Barrier Reef. None of the seasnakes found in the Great Barrier Reef World Heritage Area are endemic to the Great Barrier Reef, nor are any of them endangered.
[20]
More than 1500 species of fish live on the reef, including the
Clownfish,
Red Bass,
Red-Throat Emperor, and several species of
Snapper and
Coral Trout.
Four hundred species of corals, both
hard corals and
soft corals are found on the reef.
The majority of these spawn gametes, breeding in
mass spawning events that are controlled by the rising sea temperatures of spring and summer, the lunar cycle, and the diurnal cycle. Reefs in the inner Great Barrier Reef spawn within the week after the full moon in October, but the outer reefs spawn in November and December.
[21] The common soft corals on the Great Barrier Reef belong to thirty-six genera.
[22] 500 species of
marine algae or
seaweed live on the reef.
Environmental threats
Main articles: Environmental threats to the Great Barrier Reef
The most significant threat to the Great Barrier Reef is
climate change.
[24] Mass
coral bleaching events due to rising ocean temperatures occurred in of the summers of 1998, 2002 and 2006,
[25] and coral bleaching will likely become an annual occurrence.
[26] A draft report by
the UN Intergovernmental Panel on Climate Change states that the Great Barrier Reef is at grave risk and will be "functionally extinct" by 2030.
Climate change has implications for other forms of life on the Great Barrier Reef as well - some fish's preferred temperature range lead them to seek new areas to live, thus causing chick mortality in seabirds that prey on the fish. Climate change will also affect the population and available habitat of sea turtles.
[27]
Another key threat faced by the Great Barrier Reef is pollution and declining water quality. The rivers of north eastern Australia provide significant pollution of the Reef during tropical flood events with over 90% of this pollution being sourced from farms.
[28] Farm run-off is polluted as a result of overgrazing and excessive
fertiliser and pesticide use. Due to the range of human uses made of the water catchment area adjacent to the Great Barrier Reef,
water quality has declined owing to the sediment and chemical
runoff from farming, and to loss of coastal
wetlands which are a natural filter.
[ Wetlands Great Barrier Reef Marine Park Authority ][ Nutrient management zones in the Great Barrier Reef Catchment: A decision system for zone selection Brodie, J. ][29] It is thought that the mechanism behind poor water quality affecting the reefs is due to increased light and oxygen
competition from
algae.
[ Principal water quality influences on Great Barrier Reef ecosystems Great Barrier Reef Marine Park Authority ]
Crown-of-thorns starfish
The
crown-of-thorns starfish is a coral reef predator which preys on coral polyps. Large outbreaks of these starfish can devastate reefs. In 2000, an outbreak contributed to a loss of 66% of live coral cover on sampled reefs in a study by the CRC Reefs Research Centre.
[30] Outbreaks are believed to occur in natural cycles, by poor water quality and overfishing of the starfish's predators.
The unsustainable
overfishing of
keystone species, such as the
Giant Triton, can cause disruption to
food chains vital to life on the reef. Fishing also impacts the reef through increased pollution from boats,
by-catch of unwanted species (such as dolphins and turtles) and reef
habitat destruction from
trawling,
anchors and nets.
[32] As of the middle of 2004, approximately one-third of the
Great Barrier Reef Marine Park is protected from species removal of any kind, including fishing, without written permission.
[33]
Other threats to the Great Barrier Reef include shipping accidents, oil spills, and tropical cyclones.
Human use
The Great Barrier Reef has long been known to and utilised by the
Aboriginal Australian and
Torres Strait Islander peoples. Aboriginal Australians have been living in the area from at least 40,000 years ago,
[34] and Torres Strait Islanders since about 10,000 years ago.
[35] For these 70 or so clan groups, the reef is also an important part of their culture and spirituality.
[ Aboriginal & Torres Strait Islander Culture & Dugongs and Turtles Great Barrier Reef Marine Park Authority ]
The reef first became known to
Europeans when the
HM Bark ''Endeavour'', captained by explorer
James Cook, ran there on
June 11,
1770, sustaining considerable damage. It was finally saved after lightening the ship as much as possible and re-floating it during an incoming tide.
[36] One of the most famous wrecks was that of the
HMS ''Pandora'', which sank on
August 29,
1791, killing 35. The
Queensland Museum has been leading archaeological digs to the ''Pandora'' since 1983.
[37]
Starfish on coral - typically, tourists photograph the natural beauty of the reef.
Management
Main articles: Great Barrier Reef Marine Park
After the Royal Commissions' findings, in 1975 the
Government of Australia created the Great Barrier Reef
Marine Park and defined what activities were prohibited on the Great Barrier Reef.
[38] The park is managed, in partnership with the
Government of Queensland, through the Great Barrier Reef Marine Park Authority to ensure that it is widely understood and used in a sustainable manner. A combination of zoning, management plans, permits, education and incentives (such as
eco-tourism certification) are used in the effort to conserve the Great Barrier Reef.
In July 2004, a new zoning plan was brought into effect for the entire Marine Park, and has been widely acclaimed as a new global benchmark for the conservation of
marine ecosystems.
[39] The rezoning was based on the application of systematic conservation planning techniques, using the
MARXAN software.
[40] While protection across the Marine Park was improved, the highly protected zones increased from 4.5% to over 33.3%.
[41] At the time, it was the largest
marine protected area in the world, although as of 2006, the
Northwestern Hawaiian Islands National Monument is the largest.
[Bush to protect Hawaiian islands, BBC News, 15 June 2006]
In 2006, a review was undertaken of the ''Great Barrier Reef Marine Park Act 1975''. Some recommendations of the review are that there should be no further zoning plan changes until 2013, and that every five years, a
peer-reviewed Outlook Report should be published, examining the health of the Great Barrier Reef, the management of the reef, and environmental pressures.
A scuba diver looking at a giant clam on the Great Barrier Reef
Tourism
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 tourists, especially
scuba divers. Many cities along the Queensland coast offer daily boat trips to the reef. Several continental and coral cay islands have been turned into
resorts, including the pristine resort island of
Lady Elliot Island.
As the largest commercial activity in the region, it was estimated in 2003 that tourism in the Great Barrier Reef generates over
AU$4 billion annually.
[43] (A 2005 estimate puts the figure at
AU$5.1 billion.
[ Protecting Biodiversity Brochure 2005 Great Barrier Reef Marine Park Authority ]) Approximately two million people visit the Great Barrier Reef each year.
[44] Although most of these visits are managed in partnership with the marine
tourism industry, there are some very popular areas near shore (such as
Green Island) that have suffered damage due to overfishing and land based run off.
A variety of boat tours and cruises are offered, from single day trips, to longer voyages. Boat sizes range from
dinghies to
superyachts.
[45] Glass-bottomed boats and
underwater observatories are also popular, as are
helicopter flights. By far, the most popular tourist activities on the Great Barrier Reef are
snorkeling and diving, for which pontoons are often used, and the area is often enclosed by nets. The outer part of the Great Barrier Reef is favoured for such activities, due to water quality.
Management of tourism in the Great Barrier Reef is geared towards making tourism
ecologically sustainable. A daily fee is levied that goes towards research of the Great Barrier Reef.
This fee ends up being 20% of the GBRMPA's income.
[46] Plans of management are also in place for the popular tourist destinations of Cairns and the
Whitsunday Islands, which account for 85% of the tourism in the region.
Policies on
cruise ships,
bareboat charters, and anchorages limit the traffic on the Great Barrier Reef.
Fishing
The
fishing industry in the Great Barrier Reef, controlled by the Queensland Government, is worth
AU$1 billion annually.
[47] It employs approximately 2000 people, and fishing in the Great Barrier Reef is pursued commercially, for recreation, and as a traditional means for feeding one's family.
[ Wonky holes in the reef provide particularly productive fishing areas.]
See also
★
References
1. Great Barrier Reef Travel Guide Fodor's
2. Great Barrier Reef: no buried treasure Sarah Belfield
3. The Seven Natural Wonders of the World CNN
4. Queensland Icons National Trust Queensland
5. Great Barrier Reef MSN Encarta
6. The Devonian 'Great Barrier Reef' Western Australia's Department of Environment and Conservation
7. Representative Areas in the Marine Park Great Barrier Reef Marine Park Authority
8. Reef Bioregions of the Great Barrier Reef World Heritage Area Great Barrier Reef Marine Park Authority
9. Non-Reef Bioregions of the Great Barrier Reef Great Barrier Reef Marine Park Authority
10. Bio-region Information Sheets Great Barrier Reef Marine Park Authority
11. Snapshot of life deep in the Great Barrier Reef CSIRO
12. Fauna and Flora of the Great Barrier Reef World Heritage Area Great Barrier Reef Marine Park Authority
13. Environmental Status: Marine Mammals Great Barrier Reef Marine Park Authority
14. Environmental Status: Seagrasses Great Barrier Reef Marine Park Authority
15. Marine turtle and dugong habitats in the Great Barrier Reef Marine Park used to implement biophysical operational principles for the Representative Areas Program, , Kirstin, Dobbs, Great Barrier Marine Park Authority, 2007,
16. Environmental Status: Marine Reptiles Great Barrier Reef Marine Park Authority
17. Environmental status: birds Great Barrier Reef Marine Park Authority
18. Environmental status: birds Condition
19. Environmental Status: Sharks and rays
20. Appendix 2 - Listed Marine Species
21. Information Fact Sheets #20 Coral Spawning Great Barrier Reef Marine Park Authority
22. Soft coral atlas of the Great Barrier Reef Australian Institute of Marine Science
23. Bioerosion: an essential, and often overlooked, aspect of reef ecology Ryan Holl
24. http://www.150.theage.com.au/view_bestofarticle.asp?straction=update&inttype=1&intid=1850
25. Coral Bleaching and Mass Bleaching Events Great Barrier Reef Marine Park Authority
26. The The Daily Telegraph - January 30, 2007 - Online version
27. Climate change and the Great Barrier Reef Great Barrier Reef Marine Park Authority
28. Coastal water quality
29. Industries, Land Use and Water Quality in the Great Barrier Reef Catchment - Key Points Australian Government Productivity Commission
30. CRC REEF RESEARCH CENTRE TECHNICAL REPORT No. 32 — Crown-of-thorns starfish(Acanthaster planci) in the central Great Barrier Reef region. Results of fine-scale surveys conducted in 1999-2000.
31. Crown-of-thorns starfish on the Great Barrier Reef CRC Reef Research Centre (PDF)
32. Environmental Effects of Prawn Trawling CSIRO Marine Research
33. Marine Park Zoning Great Barrier Reef Marine Park Authority
34. Fact Sheet No. 4 - Aboriginal and Torres Strait Islander People and the Great Barrier Reef Region Great Barrier Reef Marine Park Authority
35. reefED - GBR Traditional Owners Great Barrier Reef Marine Park Authority
36.
37. HMS Pandora Queensland Museum
38. Great Barrier Reef Marine Park Act 1975 Commonwealth of Australia
39. Zoning Plan 2003 Great Barrier Reef Marine Park Authority (PDF)
40. Fernandes et al. (2005) ''Establishing representative no-take areas in the Great Barrier Reef: large-scale implementation of theory on marine protected areas'', Conservation Biology, 19(6), 1733-1744.
41. Great Barrier Reef - WWF-Australia World Wildlife Fund Australia
42. Great Barrier Reef Outlook Report
43. Summary report of the social and economic impacts of the rezoning of the Great Barrier Reef Marine Park. Great Barrier Reef Marine Park Authority (PDF)
44. Number of Tourists Visiting The Great Barrier Reef Marine Park Great Barrier Reef Marine Park Authority
45. Onboard The Tourism Operator's Handbook for the Great Barrier Reef - What You Do Great Barrier Reef Marine Park Authority
46. Onboard The Tourism Operator's Handbook for the Great Barrier Reef - How is the Money Used? Great Barrier Reef Marine Park Authority
47. Measuring the economic and financial value of the Great Barrier Reef Marine Park Access Economics Pty Ltd (PDF)
Further reading
★
★ The geomorphology of the Great Barrier Reef : development, diversity, and change, , David, Hopley, Cambridge : Cambridge University Press, 2007,
External links
★
★ Great Barrier Reef Marine Park Authority
★ CRC Reef Research Centre
★ Biological monitoring of coral reefs of the GBR
★ Great Barrier Reef (World Wildlife Fund)
★ Dive into the Great Barrier Reef from National Geographic
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