Coral reefs will be gone by the end of the century, according to a top UN Scientist. This would give coral reefs the dubious accolade of being the first entire ecosystem to have been destroyed by human activity.

Coral reef ecosystem

In the recently published book ‘Our Dying Planet‘, Professor Peter Sale writes that coral reef ecosystems are very likely to disappear by the end of this century, in what would be “a new first for mankind – the ‘extinction’ of an entire ecosystem”.

Sale, who leads a team at the United Nations University Institute for Water, Environment and Health, reports that the decline in coral reefs is mainly due to climate change and ocean acidification. Other activities, including overfishing, pollution and coastal development, have also had a devastating impact on the world’s coral reefs.

“We’re creating a situation where the organisms that make coral reefs are becoming so compromised by what we’re doing that many of them are going to be extinct, and the others are going to be very, very rare,” says Sale.

Acropora species on reef

Human impact

The use of fossil fuels and the resulting carbon emissions, which contribute to climate change, are thought to be the biggest cause of the rapid decline in coral reefs. Climate change has led to increased ocean surface temperatures, putting reef species under enormous stress and leading to coral bleaching. Ocean acidification – caused by the oceans absorbing increased amounts of carbon dioxide from the atmosphere – is also an increasing threat, making it harder for reef organisms to retrieve the minerals needed to build their skeletons.

Although around 20% of coral reefs have already been lost in the past few decades, the authors of ‘Our Dying Planet’ are careful to stress that the corals themselves may well survive the effects of human activities and the destruction they cause.

“Although corals are ancient animals and have been around for hundreds of millions of years, there have been periods of reefs, and periods where there are no reefs,” explains Mark Spalding, of the US-based environmental group Nature Conservancy and the University of Cambridge. “When climatic conditions are right they build these fantastic structures, but when they’re not they wait in the wings, in little refuges, as a rather obscure invertebrate.”

A bacterial infection called white-band disease killed virtually all the dominant staghorn coral (Acropora cervicornis) on the reefs of Belize

Impact of natural disasters

It isn’t just human activities, however, that are impacting on coral reefs. In a recent study published in the journal Ecology, natural disasters, such as earthquakes and hurricanes, are also shown to have catastrophic impacts on reef ecosystems.

The study in Ecology looked at the after-effects of a 7.3 magnitude earthquake that shook the western Caribbean in May 2009.

Having been dominated by staghorn corals for nearly 4,000 years, the Belize reefs have lost their dominant corals due to disease and climate-induced bleaching in the last 25 years, drastically weakening the remaining reef.

As a result of the rapid and dramatic change to the coral reef assemblage, the earthquake in 2009 caused lagoonal reefs in Belize to avalanche and slide into deeper water, leaving behind only sediment and the skeletal debris of corals.

Lettuce coral (Agaricia tenuifolia) colonised the reefs in Belize after staghorn corals disappeared, but mass coral bleaching resulting from high temperatures during the 1998 El Nino–Southern Oscillation caused this species to also vanish.

Immense biodiversity

Coral reefs are often considered the ‘rainforests of the sea’. Containing around a quarter of all marine species, coral reefs are hugely diverse, yet they cover just a small percentage of the world’s oceans. Not only are they important habitats for a variety of marine life, but they provide protection to shorelines, as well as contributing significantly to tourism and the fishing industry.

The highly diverse and unique chemical composition of coral reef ecosystems has also been found to contain many compounds that could be useful to the medical industry.

Conservation efforts crucial

According to Alex Rogers, a Professor of conservation biology at Oxford University, local conservation efforts can make a difference – but not forever.

“We know for certain that corals subject to low levels of stress are much more able to recover. So if you take away pressures like overfishing of coral reefs and pollution, this has profound effects on recovery. But what we’re really doing is buying time for many of these ecosystems. If climate change continues at its current rate, they will be done for eventually,” says Rogers.

Read the full article about the book ‘Our Dying Planet’ by Professor Peter Sale at the Independent.

Read the press release about the article published in the journal Ecology.

Find out more about corals on ARKive.

Helen Roddis, ARKive Species Text Author

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Australia’s Great Barrier Reef is suffering significant damage from agricultural pesticides, according to a new report by the Australian government.

Acropora florida, just one of around 400 coral species found in the Great Barrier Reef.

Looking at water quality around the Great Barrier Reef, the report found that nearly a quarter of horticultural producers and around 12% of pastoral farmers were using practices considered unacceptable by the industry, causing harmful chemicals to wash onto the Reef.

The report blamed much of the pollution on the sugar cane industry in the wet tropics of northern Queensland.

World Heritage Site under threat

The Great Barrier Reef is listed as a UNESCO World Heritage Site, and is internationally recognised for its incredible biodiversity. It contains the world’s largest collection of coral reefs, which are home to an estimated 400 coral species, together with 1,500 species of fish, 4,000 species of mollusc, and many other marine invertebrates.

The Reef also provides vital habitat for threatened species such as the dugong, green turtle and leatherback turtle, and is used by numerous bird species.

Green turtle swimming over reef.

However, this hugely diverse ecosystem faces a range of threats, particularly from the impacts of climate change. Increased water temperatures are likely to increase coral bleaching, which causes the stressed corals to lose their symbiotic algae and often leads to the death of affected corals.

Harmful chemicals such as pesticides are also impacting on the health of the Great Barrier Reef, and may be lowering its ability to withstand and recover from the effects of climate change. Pesticides have already been found up to 60 kilometres (38 miles) inside the reef, at levels known to be harmful to corals.

Bleached Acropora coral.

The pollution caused by these chemicals is thought to have been worsened by the heavy flooding and cyclone that hit northern Queensland earlier this year, flushing pollutants out to sea.

Call to limit pesticide use

The government report says that some farmers need to be more careful with their chemicals, and conservationists have called for a limit on pesticide use, as well as a ban on certain weed killers.

However, the agricultural industry has argued that the report’s findings are based on old data, and that there has been a significant change in the industry. Sugar cane producers have also said that there are no alternatives to adequately protect their crops.

The Great Barrier Reef is an important habitat for species such as the dugong, or ‘sea cow’.

While the Australian government agreed that farmers have been using more environmentally-friendly methods, it said that these had been undermined by the effects of Cyclone Yasi.

Read the full story at the BBC – Australia’s Great Barrier Reef ‘at risk from pesticide’.

Find out more about the Great Barrier Reef at the Australian Government Great Barrier Reef Marine Park Authority.

View photos and videos of species from Australia on ARKive.

Liz Shaw, ARKive Species Text Author

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The world’s oceans are in a “shocking” state and marine species may face an unprecedented extinction event, an international panel of experts has warned.

The many threats to the world’s coral reefs include increasing ocean temperatures, which can cause coral ‘bleaching’, as shown in this Acropora species.

The panel was brought together by the International Programme on the State of the Ocean (IPSO) and involved scientists from across a range disciplines. It was the first to consider the cumulative impacts of the pressures facing the oceans, including pollution, ocean acidification, ocean warming, over-fishing and hypoxia (reduced oxygen levels).

Rapid pace of change

“The findings are shocking,” said Alex Rogers, Scientific Director of IPSO and a professor of conservation biology at Oxford University. “As we considered the cumulative effect of what humankind does to the oceans, the implications became far worse than we had individually realised… almost right across the board we’re seeing changes that are happening faster than we’d thought, or in ways that we didn’t expect to see for hundreds of years.”

Overfishing has brought species such as the southern bluefin tuna to the brink of extinction.

These rapid changes include the melting of the Greenland and Antarctic ice sheets, sea level rise, and the release of methane trapped in the sea bed. More worrying is how different threats are acting together in ways that had not previously been recognised, their combined effects being worse than each threat alone.

For example, some pollutants have been found to stick to the surfaces of tiny plastic particles in the ocean, increasing the amounts of these pollutants being consumed by marine creatures. Global climate change, ocean acidification, pollution and overfishing are also working together to increase the pressures on the world’s coral reefs, many of which are now in severe decline.

Coral reefs support a huge variety of other species, including fish such as these common clownfish.

Sixth mass extinction?

The combined effects of these stresses mean that ocean ecosystems are unable to recover, being constantly under attack from multiple threats. The panel concluded that not only are we already seeing significant declines in marine species and habitats, but that we now face losing species and entire marine ecosystems, such as coral reefs, within a single generation.

Life on Earth has gone through five “mass extinction” events in the past, and human activities are now thought to be causing a sixth such event. The panel’s report said that the combination of threats to the ocean is creating the same conditions found in every major extinction in Earth’s history. Levels of carbon dioxide being absorbed by the ocean are already far greater than at the time of the last mass extinction of marine life, some 55 million years ago. The rate of the ocean’s degeneration is also far greater than anyone had predicted.

Manta ray entangled in a fishing net.

Conserving the world’s oceans

The panel’s conclusions will be presented in a report at the UN headquarters in New York later this week, when discussions will take place aimed at reforming governance of the oceans. The report calls for urgent measures to better conserve ocean ecosystems, and in particular to improve governance of the largely unprotected high seas.

IPSO’s immediate recommendations include stopping exploitative fishing, especially on the high seas where there is little effective regulation. It also recommends mapping and then reducing pollutants, such as plastics, fertilisers and human waste, which are entering the oceans. In addition, sharp reductions need to be made in greenhouse gas emissions, and research is urgently needed into ways of reducing carbon dioxide in the atmosphere.

Like many marine species, the green turtle faces a range of threats. This species is classified as Endangered by the IUCN.

One of the report’s co-authors, Dan Laffoley, Marine Chair of IUCN’s World Commission on Protected Areas, and Senior Advisor on Marine Science and Conservation for IUCN, admitted that the challenges were vast. “But unlike previous generations, we know what now needs to happen,” he said. “The time to protect the blue heart of our planet is now.”

Read the full story at IUCN – Multiple ocean stresses threaten globally significant marine extinction.

Read more about climate change on ARKive.

View photos and videos of marine species on ARKive.

Liz Shaw, ARKive Species Text Author

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When many people dream of the perfect summer vacation or holiday, visions of sandy beaches, crystal clear waters and lush forests come to mind. Islands are a home away from home for many travelers around the world but most people are unaware of the amazing biodiversity that island habitats support. This is where our partners at Seacology come in.

Seacology is an environmental nonprofit with the sole purpose of preserving the highly endangered biodiversity of islands throughout the world. In the last 400 years, the majority of the world’s plant and animal extinctions have taken place on islands. By working with indigenous island peoples, Seacology strives to find the middle ground between improving human life while maintaining the environmental integrity of islands habitats and species.

With a favorable year-round climate and isolation from large land masses, tropical islands support some of the most unique species on Earth. Here’s a sample of some of Seacology’s most recent projects, highlighting the endangered species they have helped to protect.

In exchange for a new community health clinic in Papua New Guinea, Seacology established a 988-acre no-take coastal marine conservation area providing a permanent sanctuary for many island species including the Asian giant softshell turtle, an easily recognizable species with its broad head and eyes close to the tip of its snout.

The stunning bowl coral is just one of the many corals, fish, crabs and other marine species safely protected for the next 10 years near the island of Tonga in the South Pacific. Through another agreement between Seacology and local island peoples, 368 acres of a critical marine habitat reserve are protected into the next decade in return for an updated community hall building.

Found only on the island of Rarotonga in the Cook Islands, both the male and female Cook Islands fruit-dove take turns incubating their egg until it hatches. By updating a meeting house in Rarotonga’s Muri Village to include a cyclone evacuation center and gymnasium among other important upgrades, Seacology was able to secure protection for a lagoon and surrounding forest habitat of the Cook Island fruit-dove and other species for 10 years.

Both Seacology and ARKive focus on the conservation of endangered species around the globe and by helping each other share our accomplishments, we hope to raise awareness of the species that need the most help. To learn more about Seacology’s work, check out their website, blog, or videos.

Check out some favorite endangered island species films and images in this MyARKive scrapbook!

Liana Vitali, ARKive Science, Education and Outreach Officer, Wildscreen USA

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More than three-quarters of the world’s coral reefs are seriously threatened by overfishing, pollution and climate change, according to a comprehensive new report.

The report, entitled ‘Reefs at Risk Revisited’, was compiled by the World Resources Institute (WRI) and 25 other research organisations. It builds on a 1998 analysis of coral reefs, and enables scientists to compare the changing threats to coral reefs around the world.

Damselfish feeding above a healthy Acropora colony. Acropora corals are particularly sensitive to the effects of climate change.

Changing threats

The most immediate threat to reefs is overfishing. Since the 1998 report, there has been an 80% increase in the threat from overfishing and destructive fishing, particularly in the Indian and Pacific Oceans.

The pressure on coral reefs appears to be highest in Southeast Asia, where nearly 95% of reefs are threatened.

A dead Acropora colony, several years after the use of destructive fishing methods.

However, by 2030 it is expected that the primary threat to coral reefs will be the effects of climate change. Mass coral bleaching, a stress response to warming waters in which corals expel their symbiotic algae and turn white, is becoming more frequent as ocean temperatures rise. Extreme bleaching events kill corals outright, while less extreme events can weaken corals, affect coral reproduction, reduce growth and calcification (vital for the development of the coral skeleton), and leave them vulnerable to disease.

A partly bleached boulder brain coral colony.

The report suggests that during the 2030s, roughly half of reefs will experience thermal stress sufficient to induce severe bleaching, rising to more than 95% of reefs being affected by the 2050s.

Still hope

Although the ‘Reefs at Risk’ report offers a troubling picture of the world’s coral reefs, it also offers a glimmer of hope. Reefs around the world have shown a capacity to rebound from even extreme damage, while active management is protecting reefs and aiding recovery in some areas.

“There are reasons for hope,” said Lauretta Burke, senior associate at WRI and a lead author of the report. “Reefs are resilient; and by reducing the local pressures, we can help buy time to find solutions to global threats that can preserve reefs for future generations.”

Blue rice coral is found in many parts of the United States Marine Protected Areas network.

Marine Protected Areas (MPAs) can reduce threats to reefs, often by focusing on managing overfishing and destructive fishing practices, and by reducing pollution from land.

More than a quarter of the world’s reefs are within MPAs. However, only 6% of coral reefs found in MPAs worldwide are currently rated as effectively managed, pointing to the need to designate more protected areas and improve the effectiveness of existing MPAs to protect reefs.

By tackling local threats such as overfishing and pollution head-on and by creating healthy reef systems, we may be able to “ buy time” for coral reefs in the face of climate change, the report concludes.

“The report is full of solutions – real world examples where people have succeeded to turn things around,” says Dr Mark Spalding, senior marine scientist at The Nature Conservancy.

Visit the World Resources Institute website.

Read a summary of Reefs at Risk Revisited (PDF 3.9 MB) or view the full Reefs at Risk Revisited report (PDF 6.1 MB).

Learn more about corals on ARKive.

Helen Roddis, ARKive Species Text Author

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