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Deep coral reefs in a "twilight zone" in the oceans differ greatly from those near the surface, dampening the hope that they may serve as a refuge for marine life fleeing threats such as climate change and pollution. ] 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 undergone intense bleaching, bleaching due to the warm waters that can kill corals, in 2016 and 2017.
A team of American divers studied the little-known reefs Atlantic and Pacific oceans. At a depth of 30 to 150 meters (100-500 feet), where sunlight fades, most species of coral and fish are found to be different from those closest to the surface
Image of representation. Reuters
"We were surprised to find little overlap," senior author Luiz Rocha of the California Academy of Sciences said Reuters the results published in the newspaper Science .
Less than five percent of fish and corals were found in shallow and deep waters against the previous estimate of 60-75 percent scientists, based on historical records, does it have? said.
"The potential of deep reefs to act in a refuge capacity is much less than we previously hoped," they wrote. And like shallow reefs, deep reefs have also been threatened by climate change, storms and pollution.
Divers found plastic fishing nets entangled in the deep 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. ] According to previous research, a 2016 study by the United Nations Environment Program showed that some deep reefs could act as "lifeboats" for nearby shallow reefs and connected
. cases, deep reefs "may be just as vulnerable as shallow reefs" to human pressures.
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