Status of Coral Reefs Today
More than a quarter of the world’s reefs are at high risk, and just under a third of these habitats are at moderate risk, from human disturbance. Of the four broad categories of potential threat to coral reefs evaluated, overexploitation of marine resources, including destructive fishing practices, and coastal development present the greatest threat.
Globally, 36 percent of all reefs were classified as threatened by overexploitation, 30 percent by coastal development, 22 percent by inland pollution and erosion, and 12 percent by marine pollution. When these threats are combined, 58 percent of the world’s reefs are at risk (defined as medium and high risk).
These figures are tempered by the relatively low threat faced by coral reefs in the Pacific – home to more reefs than any other part of the world. Forty-one percent of reefs in the Pacific are estimated to be at risk. Outside of this region, 70 percent of all reefs are at risk (almost 40 percent at high risk).
Most disturbing is the status of reefs in Southeast Asia – a global hot spot of coral and fish diversity. As with tropical rainforests in this region, reef ecosystems are under tremendous threat. More than 80 percent of these ecosystems are potentially at risk, primarily from coastal development, overfishing, and destructive fishing practices. Results from the Reefs at Risk analysis are presented in Reefs at Risk indicator by region and country and in the five regional highlights that follow.
Status of Coral Reefs of the World: 2008
Edited by Clive Wilkinson
Coral reefs of the world have effectively marked time since the last report in 2004. Some areas have recovered well after the climate change bleaching in 1998 and human damage; while the Indian Ocean tsunami, more bleaching in the Caribbean, and human pressures have slowed or reversed recovery.
Estimates assembled through the expert opinions of 372 coral reef scientists and managers from 96 countries are that the world has effectively lost 19% of the original area of coral reefs; 15% are seriously threatened with loss within the next 10–20 years; and 20% are under threat of loss in 20–40 years. The latter two estimates have been made under a ‘business as usual’ scenario that does not consider the looming threats posed by global climate change or that effective future management may conserve more coral reefs. However, 46% of the world’s reefs are regarded as being relatively healthy and not under any immediate threats of destruction, except for the ‘currently unpredictable’ global climate threat. These predictions carry many caveats, as explained below.
In 2008, the International Year of the Reef, there is a mixture of good and bad news in this Status of Coral Reefs of the World: 2008 report. Several major events have damaged coral reefs since December 2004 when the previous ‘Status 2004’ report was released. But there have also been major positive steps taken to conserve the world’s coral reefs. Some steps have been forward and some steps backward. Significant backward steps were:
• The Indian Ocean megathrust earthquake and tsunami struck on 26 December 2004 with enormous loss of life and disruption to Indian Ocean countries. There was considerable damage to the coral reefs of the Indian Ocean, but not at a scale comparable to human losses (Box p. 130);
• 2005 was the hottest year in the Northern Hemisphere since 1998 and this resulted in massive coral bleaching and hurricanes throughout the wider Caribbean in 2005 killing many corals and further damaging their reefs;
• Degradation of coral reefs near major centres of population continues with losses of coral cover, fish populations and probably biodiversity. This is certainly happening around the ‘Coral Triangle’, the world’s centre for marine biodiversity (p. 55);
• There is increasing evidence that global climate change is having direct impacts on more and more coral reefs with clear evidence that rising ocean acidification will cause greater damage into the future;
• Socioeconomic assessments are increasing on coral reefs and being used more in management decision making. These assessments are being employed to strengthen or re-invigorate traditional management structures, especially in the Pacific where many traditional management regimes remain intact;
Status of Coral Reefs of the World: 2008
• However, coral reef declines will have alarming consequences for approximately 500 million people who depend on coral reefs for food, coastal protection, building materials and income from tourism. This includes 30 million who are virtually totally dependent on coral reefs for their livelihoods or for the land they live on (atolls);
• Problems for coral reef managers are increasing, as 50% the world’s population will live along coasts by 2015, putting unsustainable pressures on coastal resources. The reefs they manage will contain less attractive but tougher corals. Rising food and fuel prices, commercialisation of fishing activities and the global financial crisis are resulting in over-fishing and serial depletion of fish stocks in many poor countries; and
• The solution remains in establishing more Marine Protected Areas linked into networks and managed by all stakeholders, especially user communities.
Countering such gloomy news, are some major advances:
• Two enormous marine protected areas (MPAs) focussed on coral reefs have been declared in the Pacific; the Papahānaumokuākea Marine National Monument covering the North-west Hawaiian Islands and the Phoenix Islands Protected Area (PIPA) were declared by the governments of USA and Kiribati respectively (Boxes p. 224, 195);
• Large areas of the coral reefs around New Caledonia have been given World Heritage listing (Box p. 184), and more areas are under consideration elsewhere;
• Coral reefs in the Indian Ocean, especially in the Seychelles, Chagos and the Maldives, and Palau in the Western Pacific, have continued to recover from the devastating bleaching of 1998;
• In December 2007 President Yudhoyono of Indonesia gained support and funding from world leaders for the ‘Coral Triangle Initiative’ to conserve the coral reef resources of Southeast Asia (p. 55);
• This initiative theme was expanded to include Western Pacific countries that border the Coral Triangle when President Remengesau of Palau instigated the Micronesia Challenge with other leaders who made commitments to conserve 20% of the land and 30% of the waters as protected areas in linked networks (p. 48);
• Soon after, Prime Minister Ingraham of The Bahamas gathered 4 of his neighbours to form the Caribbean Challenge that seeks to conserve 30% of their coastal resources;
Read the entire report: CLICK HERE
In addition, there have been other positive activities for coral reefs including:
• The International Coral Reef Initiative, currently co-chaired by Mexico and the USA, declared 2008 as the International Year of the Reef and developed major awareness raising campaigns around the world;
• The 11th International Coral Reef Symposium assembled 3500 scientists, managers and decision makers in Ft Lauderdale, USA, in July 2008 to bring the power of science to coral reef conservation (p. 43);
• Reef Check has organised 20 700 signatures on the ‘Declaration of Reef Rights’ petition launched in the International Year of the Reef;
• The Pew Environment Group is working with developed country governments to declare very large areas as no-take marine reserves, including the Coral Sea of Australia, the Northern Mariana Islands, the Chagos Archipelago in the Indian Ocean, and the Kermadec Trench, off New Zealand;
Major Changes Needed for Coral Reef Survival
To prevent coral reefs around the world from dying off, deep cuts in carbon dioxide emissions are required, says a new study from Carnegie's Katharine Ricke and Ken Caldeira. They find that all existing coral reefs will be engulfed in inhospitable ocean chemistry conditions by the end of the century if civilization continues along its current emissions trajectory.
Their work will be published July 3 by Environmental Research Letters.
Coral reefs are havens for marine biodiversity and underpin the economies of many coastal communities. But they are very sensitive to changes in ocean chemistry resulting from greenhouse gas emissions, as well as to coastal pollution, warming waters, overdevelopment, and overfishing.
Ricke and Caldeira, along with colleagues from Institut Pierre Simon Laplace and Stanford University, focused on the acidification of open ocean water surrounding coral reefs and how it affects a reef's ability to survive.
Coral reefs use a mineral called aragonite to make their skeletons. It is a naturally occurring form of calcium carbonate, CaCO3. When carbon dioxide, CO2, from the atmosphere is absorbed by the ocean, it forms carbonic acid (the same thing that makes soda fizz), making the ocean more acidic and decreasing the ocean's pH. This increase in acidity makes it more difficult for many marine organisms to grow their shells and skeletons, and threatens coral reefs the world over.
Using results from simulations conducted using an ensemble of sophisticated models, Ricke, Caldeira, and their co-authors calculated ocean chemical conditions that would occur under different future scenarios and determined whether these chemical conditions could sustain coral reef growth.
Ricke said: "Our results show that if we continue on our current emissions path, by the end of the century there will be no water left in the ocean with the chemical properties that have supported coral reef growth in the past. We can't say with 100% certainty that all shallow-water coral reefs will die, but it is a pretty good bet."
Deep cuts in emissions are necessary in order to save even a fraction of existing reefs, according to the team's results. Chemical conditions that can support coral reef growth can be sustained only with very aggressive cuts in carbon dioxide emissions.
"To save coral reefs, we need to transform our energy system into one that does not use the atmosphere and oceans as waste dumps for carbon dioxide pollution. The decisions we make in the next years and decades are likely to determine whether or not coral reefs survive the rest of this century," Caldeira said.