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All coral reefs in western Indian Ocean ‘at high risk of collapse in next 50 years’ | Coral

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A new assessment shows that all coral reefs in the western Indian Ocean are at severe risk of collapse in the next 50 years due to global warming and overfishing.

From the Seychelles to the Delagoa region off the coast of Mozambique and southern Africa, coral reef systems are at risk of functionally extinction by the 1970s, with massive loss of biodiversity, threatening livelihoods and food sources for hundreds of thousands of people.

The study, published today in the journal Nature Sustainability, examined coral reefs in 10 countries around the western Indian Ocean. He analyzed the health of 11 subregions using the International Union for Conservation of Nature’s (IUCN) Red List Ecosystem Framework, similar to the method used to examine the risk of extinction for a plant or animal.

The assessment found that corals in island nations in particular were significantly threatened by rising water temperatures due to global warming, which makes bleaching events – when corals expel the algae that lives in their tissues, causing them to turn completely white – Most common. Coral reefs in eastern and southern Madagascar, Comoros and the Mascarene Islands have been classified as critically endangered.

Coral reefs in northern Seychelles and along the entire East African coast have been classified as vulnerable to collapse due to overfishing – especially from top predators – which alters their habitat and promotes the accumulation of various algae that can choke off corals.

While global coral decline has been established for some time, area-specific assessments of specific regions have provided greater clarity about the causes and extent of damage, said David Obura, head of the Coral Reef Group at the International Union for Conservation of Nature, who led the study. .

“The most immediate threat is from climate change up to 50 years from now. But as we estimate 50 years into the future, whether we can meet 1.5°C [rise] The future or not depends on what we do in the next ten years. So, it’s really a 10-year horizon that we have to worry about.”

“Coral reef collapse means that they are functionally extinct as a reef system. You may still find some species there but they won’t be able to build reefs anymore. All the services we get – coastal protection from sea level rise, tourism, fisheries, especially Low-income families and communities – are at risk. The tourism sector is huge in East Africa and depends on coral reefs.”

Since the 1950s, the world’s coral reef cover has been halved due to global warming, overfishing, pollution and habitat destruction. Ecosystems, which are vital nurseries for young fish globally, are expected to continue to deteriorate as the climate warms.

Their assessment revealed overhunting of predators in all of the coral reefs for which there is data, said Michel Gudka, senior scientist at Cordeo East Africa and co-author of the study.

“These findings highlight the need to improve local fisheries management to ensure the health of coral reef systems and secure sustainable fish stocks, supporting employment opportunities for a quarter of a million people in the region,” Gudka said.

Besides reductions in greenhouse gas emissions, Obura said better implementation of fishing rules and greater involvement of local communities in managing coral reefs could help preserve their survival.

“This assessment reaffirms the urgency of the interconnected climate and biodiversity crises addressed by Cop26 last month in Glasgow, and Cop15 [biodiversity summit] In a few months in Kunming. We need to take decisive action to address both global threats to coral reefs from climate change, and local threats, such as overfishing,” he said.

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