Great Barrier Reef
From Free net encyclopedia
The Great Barrier Reef is the world's largest coral reef. The reef is located in the Coral Sea, off the coast of Queensland in north-east Australia. It stretches over 2000 kilometres in length and can be seen from space.
The Great Barrier Reef is a large system of about 900 islands and over 3000 coral reefs, which mostly lie some distance from the mainland coastline. 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 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 organism in the world. In reality it is made up of many millions of tiny organisms, as are all coral formations.
A large part of the reef is protected by the Great Barrier Reef Marine Park.
Contents |
Age
The Great Barrier Reef first became known to Europeans when the explorer Captain James Cook ran aground there, on June 11, 1770. The Great Barrier Reef however was known to Indigenous Australians whose occupation of the Australian continent is thought to extend back 40,000 to 60,000 years or more. [1] [2].
According to the 2005 fact sheet published by the Marine Park Authority of the Australian Government [3], the current reef structure is believed to have begun growing on an older platform about 18,000 years ago, but the oldest datable coral on the reef now is a species of Porites known as boulder coral, which is only about 1,000 years old (it grows at about 1 centimetre/year).
The research outcomes funded by the CRC Reef Research Centre [4] estimates the present reef structure at 6,000 to 8,000 years old, formed upon coral dating back half a billion years. Reefs fluctuate (grow and recede) as the sea level changes. An ancient barrier reef similar to the Great Barrier Reef can be found in The Kimberleys.
History
The reef has, over the years, brought many ships to grief. James Cook's HM Bark Endeavour hit the reef in 1770 and sustained considerable damage. It was finally saved after lightening the ship as much as possible and re-floating it during an incoming tide. One of the most famous wrecks is 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. [5]
Environmental threats
Runoff and coastal development
The coastline of north eastern Australia has no major rivers, except during tropical flood events caused by cyclones (hurricanes), several major urban centres with Cairns [6], Townsville [7], Mackay [8], Rockhampton [9] and the industrial city of Gladstone [10]. Cairns and Townsville are the largest of these coastal cities with populations of approximately 150,000 each [11]. Unlike most reef environments the Great Barrier Reef is the only one where the catchment area is home to industrialised urban areas and where extensive areas of coastal lands and rangelands have been used for agricultural and pastoral purposes.
Global warming and coral bleaching
Some people believe that the most significant threat to the status 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. As was seen at those times, under the stress of waters that remain too warm for too long, corals expel their photosynthesising zooxanthellae and turn colourless, revealing their white calcium carbonate skeletons, and if the water does not cool within about a month the coral will unfortunately die. Australia has just experienced its warmest year on record and abnormally high sea temperatures during summer (2006) have caused massive coral bleaching in the Keppel island group.
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. While some believe that an upward trend in temperature will cause much more coral bleaching, others point to data that demonstrates that the global temperature has never changed by more than a degree for a very long time. Image:CrownofThornsStarfish Fiji 2005-10-12.jpg
Crown-of-Thorns starfish
Crown-of-Thorns starfish are thought to be natural predators of corals. The exact origin of this species is unknown, and it is only speculated that they are native to Australia. They have a life cycle with many eggs released annually, that enables this species to boom-and-bust like locusts in a desert. The cycles are thought to be enhanced by declines in water quality such as excess nutrients from farm runoff. Since scientists and other users of the reef have been able to observe crown-of-thorns outbreaks, about 1/3 of the entire system has been affected since the 1960s. The link to an animation of Crown-of-Thorns starfish outbreaks illustrates, using data collected from the Australian Institute of Marine Science Long Term Monitoring Program, the occurrence of Crown-of-Thorns starfish outbreaks [12]. In addition, the Giant Triton, a natural predator of the Crown-of-Thorns starfish, is often overfished as its shell is prized by collectors.
Fishing
The fishing industry in the GBR is worth AU$104 million annually [13]. It employs approximately 2000 people. There are 3 main types:
- commercial
- recreational
- traditional
Effects of Fishing
Disruption to food chains is caused by unsustainable overfishing of key species. The Queensland government announced a Coral Finfish Management Plan (in practice 2003) aimed at reducing the annual commercial catch to 1996 levels and increasing the minimum legal size.
Up until mid-2004, only 4.6% of the Great Barrier Reef World Heritage area was protected from fishing. (It is now one third.) The main impacts from fishing are
- Overfishing of key species (eg. Giant Triton)
- Pollution from boats
- Bycatch (species that they’re not looking for, e.g. crabs, dolphins, turtles, dugongs)
- Reef damage (anchors, nets)
- Habitat destruction from trawling [14]
Shipping and oil
Shipping accidents are a real concern, as commercial shipping routes pass through the Great Barrier Reef. There have been two groundings of large container vessels over the past few years from negligence. Ships also have been known to discharge waste and the antifouling paint on the hulls is toxic. Also, it is suspected that the Reef is the cap to an oil trap, as it is calcium carbonate. Before it was World Heritage listed, there was some speculation about drilling for oil and gas there. Although there is no oil drilling on the reef, oil spills are still a frequent occurrence.
Managing the Great Barrier Reef
There are approximately two million visitors to the Great Barrier Reef each year. [15] 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. Any impacts from tourist activity merely exacerbate the more pronounced effects of land based run-off and overfishing.
The Australian Government manages the reef, through the Great Barrier Reef Marine Park Authority[16] and in partnership with the state of Queensland, 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.
The Great Barrier Reef was selected as a World Heritage Site in 1981. On July 1, 2004 the Great Barrier Reef Marine Park became the largest protected sea area in the world when the Australian Government increased the areas protected from extractive activities (such as fishing) from 4.6% to 33.3% of the park. [17]
External links
- Official site of the Great Barrier Reef Marine Park
- Scientific research centre for the Great Barrier Reef
- Biological monitoring of coral reefs of the GBR
- Photos of the Great Barrier Reef - Terra Galleria
- Australia Underwater - All about diving in Australia - includes photo gallery from all around Australia.
- Great Barrier Reef (World Wildlife Fund)
- Dive into the Great Barrier Reef from National Geographic
Template:World Heritage Sites In Australiabg:Голям бариерен риф ca:Gran barrera de corall cs:Velký bariérový útes da:Great Barrier Reef de:Great Barrier Reef et:Suur Vallrahu es:Gran barrera de coral fr:Grande barrière de corail gl:Gran Barreira de Coral it:Grande barriera corallina he:שונית המחסום הגדולה lb:Great Barrier Reef lt:Didysis barjerinis rifas nl:Groot Barrièrerif ja:グレート・バリア・リーフ no:Great Barrier Reef nn:Det store barriererevet pl:Wielka Rafa Koralowa pt:Grande Barreira de Coral ru:Большой барьерный риф simple:Great Barrier Reef sk:Veľký koralový útes sl:Veliki koralni greben sr:Велики корални гребен fi:Iso valliriutta sv:Stora barriärrevet zh:大堡礁