The ocean has lost half its coral reef coverage, study finds

A Canadian-led team of scientists has concluded that tropical coral reefs that feed millions around the world have lost about half their ability to support human communities since 1950.

"I don't think any of us expected the declines to be as big as we found," said Tyler Eddy of Memorial University in St. John's, lead author of the paper published Friday in the journal One Earth.

The paper is the first to tote up the cumulative effects of threats faced by tropical coral reefs from overfishing to pollution to climate change, the authors say.

"This is the first study that puts it all together," Eddy said.

It combines data from myriad sources.

Just the figures on reef extent drew on 14,705 surveys from 3,582 reefs in 87 countries. The conclusions on biodiversity were made from a database with more than one billion records on 100,000 species from plankton to mammals.

"We had to spend a lot of time standardizing the data," said co-author William Cheung of the University of British Columbia. "That was a big part of the analysis."