Instruct: Given a question, retrieve relevant documents that can help answer the question.
Query: How much of the Great Barrier Reef is bleached?
Above-average sea water temperatures caused by global warming is the leading cause of coral bleaching.[2] According to the United Nations Environment Programme, between 2014 and 2016 the longest recorded global bleaching events killed coral on an unprecedented scale. In 2016, bleaching of coral on the Great Barrier Reef killed between 29 and 50 percent of the reef's coral.[3][4][5] In 2017, the bleaching extended into the central region of the reef.[6][7] The average interval between bleaching events has halved between 1980 and 2016.[8]
One of the notable issues with marine conservation in Australia is the protection of the Great Barrier Reef. The Great Barrier Reef's environmental pressures include water quality from runoff, climate change and mass coral bleaching, cyclic outbreaks of the crown-of-thorns starfish, overfishing, and shipping accidents. The government of Queensland currently kills sharks in the Great Barrier Reef using drum lines, causing damage to the marine ecosystem.
Global warming may have triggered the collapse of reef ecosystems throughout the tropics. Increased global temperatures are thought by some to bring more violent tropical storms, but reef systems are naturally resilient and recover from storm battering. Most people agree that an upward trend in temperature will cause much more coral bleaching; others suggest that while reefs may die in certain areas, other areas will become habitable for corals, and new reefs will form. However, the rate at which the mass bleaching events occur is estimated to be much faster than reefs can recover from, or adjust to.
The Belize Barrier Reef has been affected by mass-bleaching events. The first mass bleaching occurred in 1995, with an estimated mortality of 10 percent of coral colonies, according to a report by the Coastal Zone Management Institute in Belize. A second mass-bleaching event occurred, when Hurricane Mitch struck in 1998. Biologists observed a 48 percent reduction in live coral cover across the Belize reef system.
In Australia, the Great Barrier Reef is protected by the Great Barrier Reef Marine Park Authority, and is the subject of much legislation, including a biodiversity action plan. Australia compiled a Coral Reef Resilience Action Plan. This plan consists of adaptive management strategies, including reducing carbon footprint. A public awareness plan providezs education on the "rainforests of the sea" and how people can reduce carbon emissions.
The two latter reefs are much closer to Lord Howe Island, New South Wales, (about ) than to the southernmost island of the rest of the territory, Cato Island. The islands, cays and reefs of the Great Barrier Reef are not part of the territory, belonging to Queensland instead. The outer edge of the Great Barrier Reef is the boundary between Queensland and the Coral Sea Islands Territory.
The Florida Reef is the only living coral barrier reef in the continental United States. It is also the third largest coral barrier reef system in the world, after the Great Barrier Reef and the Belize Barrier Reef. The reef lies a little bit off of the coast of the Florida Keys. A lot of the reef lies within John Pennekamp Coral Reef State Park, which was the first underwater park in the United States. The park contains a lot of tropical vegetation, marine life, and seabirds. The Florida Reef extends into other parks and sanctuaries as well including Dry Tortugas National Park, Biscayne National Park, and the Florida Keys National Marine Sanctuary. Almost 1,400 species of marine plants and animals, including more than 40 species of stony corals and 500 species of fish, live on the Florida Reef. The Florida Reef, being a delicate ecosystem like other coral reefs, faces many threats including overfishing, plastics in the ocean, coral bleaching, rising sea levels, and changes in sea surface temperature.
In 2001, the GBRMPA released a report about the declining water quality in the Great Barrier Reef and detailed the importance of this issue. In response to this report, in 2003, the Australian and Queensland governments launched a joint initiative to improve the quality of water entering the Great Barrier Reef. The decline in the quality of water over the past 150 years (due to development) has contributed to coral bleaching, algal blooms, and pesticide pollution. These forms of pollution have made the reef less resilient to climate change.
Much of Larkum's research has been on marine algae, seagrasses and coral reef. He has done considerable research on photoinhibition, UV inhibition, photosynthesis and light harvesting. Since 1997, a great part of his research has been devoted to understanding the process of mass coral bleaching, more specifically the bleaching of the Great Barrier Reef. Some of his research has also studied novel cyanobacteria, such as Acaryochloris. He has discovered a number of new taxa in the seagrass genus Halophila. One of these is the species of "Halophila" from One Tree Island on the Great Barrier Reef. He has written eight books and over 250 articles.
Bleaching events in benthic coral communities (deeper than ) in the Great Barrier reef are not as well documented as those at shallower depths, but recent research has shown that benthic communities are just as negatively impacted in the face of rising ocean temperatures. Five Great Barrier Reef species of large benthic corals were found bleached under elevated temperatures, affirming that benthic corals are vulnerable to thermal stress.
The two latter reefs are much closer to Lord Howe Island, New South Wales, (about ) than to the southernmost island of the rest of the territory, Cato Island. The islands, cays and reefs of the Great Barrier Reef are not part of the territory, belonging to Queensland instead. The outer edge of the Great Barrier Reef is the boundary between Queensland and the Coral Sea Islands Territory.
Reef scientist Terry Done has predicted that a one-degree rise in global temperature would result in 82% of the reef bleached—two degrees would result in 97%, while three degrees would result in "total devastation". A predictive model based on the 1998 and 2002 bleaching events has concurred that a temperature rise of three degrees would result in total coral mortality.
According to the 2014 report of the Australian Government's Great Barrier Reef Marine Park Authority (GBRMPA), says that climate change is the most significant environmental threat to the Great Barrier Reef, while the other major environmental pressures are listed as decreased water quality from land-based runoff, impacts from coastal development and some persistent impacts from fishing activities. The reef is also threatened by storms, coral bleaching and ocean acidification. The 2014 report also shows that, while numerous marine life species have recovered after previous declines, the strength of the dugong population is continuing to decline. Terry Hughes, Federation Fellow, ARC Centre of Excellence for Coral Reef Studies at James Cook University, wrote in a 14 August 2014 "Conversation" piece that harmful government policies and ongoing conflicts of interest over mining royalties are risks of an equivalent magnitude.
In July 2017 UNESCO published in a draft decision, expressing serious concern about the impact of coral bleaching on the Great Barrier Reef. The draft decision also warned Australia that it will not meet the targets of the Reef 2050 report without considerable work to improve water quality.
Chaetodon rainfordi is a species of marine angelfish with a range restricted to Papua New Guinea, the Great Barrier Reef and Lord Howe Island. Greater than 50% of its distribution is within the protected waters of Australia's Great Barrier Reef Marine Park. There has been a significant population decline of "C. rainfordi" in the Great Barrier Reef due to extensive coral loss, its primary food source. It inhabits coastal and offshore reefs at depths of .
Ocean acidification can also lead to increased sea surface temperature. An increase of about 1 or 2 °C can cause the collapse of the relationship between coral and zooxanthellae, possibly leading to bleaching. Average sea surface temperature in the Great Barrier Reef is predicted to increase between 1 and 3 °C by 2100. This breakdown of the relationship between the coral and the zooxanthellae occurs when Photosystem II is damaged, either due to a reaction with the D1 protein or a lack of carbon dioxide fixation; these result in a lack of photosynthesis and can lead to bleaching.
Anemonefish and their host anemones are found on coral reefs and face similar environmental issues. Like corals, anemone's contain intracellular endosymbionts, zooxanthellae, and can suffer from bleaching due to triggers such as increased water temperature or acidification. The other threat to anemonefish is collection for the marine aquarium trade. The Great Barrier Reef Marine Park Authority manages collection by zoning reefs as open or closed and normally a breeding pair of adults or sub-adults is removed, leaving at least one anemonefish behind. While bleaching was found to be a cause of anemone and anemonefish decline in the Keppel Islands, anemones and anemonefish were still present on bleached reefs in the closed zones however they were absent from bleached reefs in the open zones, suggesting that collection compounds the impact of bleaching. A survey published in 2014 found 58% of sites surveyed on the Great Barrier Reef did not have anemones or anemonefishes, and at sites where they were present, numbers were generally low and suggested that current regulations may not be sufficient to prevent localised extinctions nor to ensure that reproductive success is not adversely impacted. This species was not evaluated in the 2012 release of the IUCN Red List.
The US National Oceanic and Atmospheric Administration (NOAA) monitors for bleaching "hot spots", areas where sea surface temperature rises 1°C or more above the long-term monthly average. The "hot spots" are the location in which thermal stress is measured and with the development of Degree Heating Week (DHW), the coral reef's thermal stress is monitored.[75][76] Global coral bleaching is being detected earlier due to the satellite remote sensing the rise of sea temperatures.[75][77] It is necessary to monitor the high temperatures because coral bleaching events are affecting coral reef reproduction and normal growth capacity, as well as it weakening corals, eventually leading to their mortality.[77] This system detected the worldwide 1998 bleaching event,[78][79] that corresponded to the 1997–98 El Niño event.[80] Currently, 190 reef sites around the globe are monitored by the NOAA, and send alerts to research scientists and reef managers via NOAA Coral Reef Watch (CRW) website.[81] By monitoring the warming of sea temperatures, the early warnings of coral bleaching, alerts reef managers to prepare and draw awareness to future bleaching events.[81] The first mass global bleaching events were recorded in 1998 and 2010, which was when the El Niño caused the oceans temperatures to rise and worsened the corals living conditions.[36] The 2014–2017 El Niño was recorded to be the longest and most damaging to the corals, which harmed over 70% of our coral reefs.[36] Over two thirds of the Great Barrier Reef have been reported to be bleached or dead.[36]
Royal Commissions disallowed oil drilling in the Great Barrier Reef, in 1975 the Government of Australia created the Great Barrier Reef Marine Park and prohibited various activities. The Great Barrier Reef Marine Park does not include the entire Great Barrier Reef Province. The park is managed, in partnership with the Government of Queensland, through the Great Barrier Reef Marine Park Authority to ensure that it is used in a sustainable manner. A combination of zoning, management plans, permits, education and incentives (such as eco-tourism certification) are employed in the effort to conserve the reef.
Usually, it is hard to distinguish whether the reason for coral bleaching is human activities or natural reasons such as storms or bacterial fluctuations. But in the case of the Belize Barrier Reef, many factors which make the distinction difficult do not apply. Human population in this area is much more sparse than the corresponding areas near other coral reefs, so the human activity and pollution are much lower compared to other coral reefs and the Belize reef system is in a much more enclosed area.
The Amazon Reef is at risk of coral bleaching, an issue prevalent with other reefs such as the Great Barrier Reef located off the coast of Australia.
Nevertheless, most coral reef researchers anticipate severely negative effects from climate change already occurring, and potentially disastrous effects as climate change worsens. The future of the Reef may well depend on how much the planet's climate changes, and thus, on how high atmospheric greenhouse gas concentration levels are allowed to rise. On 2 September 2009, a report by the Australian Great Barrier Reef Marine Park Authority revealed that if carbon dioxide levels reached 450 parts per million corals and reef habitats will be highly vulnerable. If carbon dioxide levels are managed at or below 380 parts per million they will be only moderately vulnerable and the reefs will remain coral-dominated.
The Reserve Bank deputy governor Philip Lowe stated in February 2012 that tourism in Australia is having undergo structural changes because of a contraction in the sector due to the impact of a high Australian dollar. By 2012, the estimated value of tourism in the Great Barrier Reef region had reached $5.5 billion. In the wake of Cyclone Marcia, a marketing campaign urged people to visit the region to help it recover. In response to the coral bleaching event of 2016, where only 7% of the reef was unaffected, the tourism industry created a hashtag, #GBRtoday showing healthy corals. Also in 2016, the Australian government asked for a chapter on climate change and the Great Barrier Reef to be removed from UNESCO's report on the status of the Great Barrier Reef over concerns it could impact on tourism. Domestic tourism to the reef subsequently fell.
According to the GBRMPA in 2014, the most significant threat to the status of the Great Barrier Reef is climate change, due to the consequential rise of sea temperatures, gradual ocean acidification and an increase in the number of "intense weather events". Hughes writes of "the demonstrable failure of the state and Commonwealth" to address the issue of climate change in his August 2014 article. Furthermore, a temperature rise of between two and three degrees Celsius would result in 97% of the Great Barrier Reef being bleached every year.
The Great Barrier Reef along the coast of Australia experienced bleaching events in 1980, 1982, 1992, 1994, 1998, 2002, 2006, 2016 and 2017.[45][46] Some locations suffered severe damage, with up to 90% mortality.[47] The most widespread and intense events occurred in the summers of 1998 and 2002, with 42% and 54% respectively of reefs bleached to some extent, and 18% strongly bleached.[48][49] However coral losses on the reef between 1995 and 2009 were largely offset by growth of new corals.[50] An overall analysis of coral loss found that coral populations on the Great Barrier Reef had declined by 50.7% from 1985 to 2012, but with only about 10% of that decline attributable to bleaching, and the remaining 90% caused about equally by tropical cyclones and by predation by crown-of-thorns starfishes.[51] A global mass coral bleaching has been occurring since 2014 because of the highest recorded temperatures plaguing oceans. These temperatures have caused the most severe and widespread coral bleaching ever recorded in the Great Barrier reef. The most severe bleaching in 2016 occurred near Port Douglas. In late November 2016 surveys of 62 reefs showed that long term heat stress from climate change caused a 29% loss of shallow water coral. The highest coral death and reef habitat loss was inshore and mid-self reefs around Cape Grenville and Princess Charlotte Bay.[52] The IPCC's moderate warming scenarios (B1 to A1T, 2°C by 2100, IPCC, 2007, Table SPM.3, p.13[53]) forecast that corals on the Great Barrier Reef are very likely to regularly experience summer temperatures high enough to induce bleaching.[48]