Saturday, October 23

Global Coral Cover Has Halved Since 1950s, Analysis Finds | Environment

The world’s coral reef cover has been cut in half since the 1950s, devastated by global warming, overfishing, pollution and habitat destruction, according to an analysis of thousands of reef studies.

From the 1,430-mile (2,300 km) Great Barrier Reef in Australia to the Saya Bank of Malha in the Indian Ocean, coral reefs and the diversity of fish species they support are in sharp decline, a trend that is predicted to continue on the planet. continues to heat up in the 21st century.

A review of 14,705 reef censuses in 87 countries found that the effort required to maintain fish catches had increased dramatically since the mid-1990s, reflecting their declining health, with catches of reef species reaching their peak. maximum in 2002 and declining since then.

the study, published Friday in One Earth magazine, found that species diversity on reefs has declined by more than 60% and total reef coverage had been cut by about half, accompanied by a similar drop in services. that ecosystems provide to human populations.

A turtle swimming off Heron Island in Australia's Great Barrier Reef
A turtle swimming off Heron Island in the Great Barrier Reef. Australia has been severely affected by coral bleaching in recent years. Photograph: STR / AFP / Getty

Coral reefs are a vital source of food for millions of people around the world, especially indigenous communities on islands where fish is the main source of animal protein, and the researchers said the decline raised fears about food stability. future.

While the review of data for 3,582 reefs covered only the period from 1957 to 2007, the scientists said they were confident that the global trend had continued, with bleaching, disease and disturbances driving declines.

Tyler Eddy, a research scientist at Memorial University of Newfoundland who led the study, said that although the decline of coral reef ecosystems had long been recorded nationally, he was surprised by the extent of the scale of the global decline. .

“Coral reefs are among the most sensitive ecosystems on the planet, so they are the first to really experience these effects of climate change. There are quite dramatic declines in the 1960s and 1970s. Then in the 1980s, there is still a slight decrease in coverage over time, but it’s not that steep, “he said.

“If you look at country-level trends in coral reef coverage, we see that some of the biggest declines are in Papua New Guinea, Jamaica and Belize.”

While reviewing the surveys, Eddy said the researchers noticed that the species composition on the reef was changing in some areas, with temperature-sensitive fish declining and more resistant species becoming dominant.

John Bruno, a marine ecologist at the University of North Carolina and a co-author of the study, said that despite regional differences, the global health of coral reefs had continued to decline.

“Unfortunately, we have continued to lose coral from most of the world’s reefs since the data for this study ended. Marine heat waves are intensifying rapidly, leading to more frequent and severe bleaching events, even on some of the most isolated and pristine coral reefs in the world, ”he said.

In the Caribbean, a recent study found that reefs had been declining by about 0.25% a year, with only about 10% of the seafloor occupied by live coral in 2017.

“In recent years, the reefs of the Caribbean have been hit by hurricanes and new diseases, both related to the warming of the oceans. Frankly, the global picture for coral reefs is pretty bleak, “added Bruno.

The world’s oceans absorbed more than 90% of the heat trapped by greenhouse gases, and average water temperatures have continued to rise as the planet warms.

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