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Deepsea coral reefs are not protected from the effects of shipping. via Deep Sea Biology Society

World - 'Secret Rainforests' Have Been Discovered Deep in Our Oceans. Here's What That Could Mean

Mention coral reefs and we all tend to think of underwater forests just beyond the surf. But if you could venture further out into the deep oceans, you would find another type of coral reef – hundreds of metres below the surface.

A new study has identified 116 deepsea coral reefs which scientists say are every bit as much in need of protection as the coastal reefs visited by snorkelers every year. They lie between 200 and 1,200 metres deep in waters where no single nation has jurisdiction.

The value of coral reefs in the marine ecosystem has long been recognized. Although they cover just 0.1% of the seafloor, they provide a home for a quarter of all marine life. Scientists warn that climate change could kill all of them by 2100 unless action is taken.

Rainforests of the sea

Unlike coastal coral reefs, the deepsea corals have evolved to live below the photic zone, the uppermost part of the sea where light penetrates. While 845 reef building coral species live in the photic zone, only six species are known to form deep water reefs.

Now the first comprehensive survey of deep sea coral reefs has been published, pinpointing the location of some of them. And there are probably many more high seas reefs yet to be discovered, says co-author Daniel Wagner, writing in the journal Science.

Describing coral reefs as “the rainforests of the seas”, Wagner points out that high-seas reefs “are some of the most under-surveyed of all ocean ecosystems”, adding that because they are not protected by the laws of any country, “they are among the most vulnerable and potentially overexploited reefs on Earth”.

The coalition had planned to begin surveying more high-seas coral reefs this year, but its first two expeditions have had to be postponed until 2022, due to COVID-19.

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