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OSLO – Deep coral reefs in a "twilit zone" in the oceans differ greatly from those near the surface, dampening the hope that they may be a haven for the marine life fleeing threats such as climate change and pollution Thursday.
Coral reefs in shallow waters around the world are among the ecosystems most at risk from climate change. The Great Barrier Reef off Australia has suffered from intense bleaching, caused by the warm waters that can kill coral, in 2016 and 2017.
A team of American divers investigated little known reefs in the Atlantic and Pacific oceans. The depth of 30 and 150 meters (100 and 500 feet) where the sunlight fades reveals that most species of corals and fish do not look like those of the surface
"We were surprised to see little overlap. California Academy of Sciences said findings published in the journal Science.
Less than 5 percent of fish and corals were found in shallow, deep waters against the previous estimate of 60 to 75 percent scientists, based on historical records, he said: " The potential for deep reefs to act in a refuge capacity is much less than we had hoped for before, "they wrote. And like shallow reefs, deep reefs have also been threatened by climate change, storms and pollution.
Divers discovered plastic fishing nets entangled in deep Philippine corals and deep corals damaged by the warm waters of the Bahamas.
Rocha said scientists were trying to place temperature sensors in the twilight zone to see how deep the reefs were exposed to rising ocean temperatures, which are the most extreme at the surface. around the world like shallow reefs, he felt. Some reefs, such as those at the mouth of the Amazon River, exist only in the depths.
The authors advocate better guarantees for deep reefs, for example by expanding protected areas and prohibiting bottom trawlers that can scratch the seabed. A 2016 study by the United Nations Environment Program found that some deep reefs could be "lifeboats" for the nearer, shallower, interconnected reefs
. to be as vulnerable as shallower reefs "to human pressures.
Details of the scientific study: science.sciencemag.org/content/361/6399/281
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