Coral reefs are often referred to as the "rainforests of the sea." | Raimundo Fernandez Diez via Getty

How Deep-Sea Coral Reefs Protect Marine Biodiversity

A recent scientific study recorded over 116 deep-ocean coral reefs and advocates for better marine protection.

Scientists have recorded over 116 deep-ocean coral reefs, which they say are as important to preserving marine biodiversity as their coastal counterparts.

This marks the first comprehensive study of coral reefs in the high seas, which make up approximately 66 percent of the world’s oceans. Its publication coincides with the launch of the Coral Reefs on the High Seas Coalition, a new group formed by scientists and non-profit organizations — such as the Deep Sea Biology Society — to survey the deep ocean reefs and advocate for their protection.

Scientific journal Frontiers in Marine Science published the new study, titled Coral Reefs of the High Seas: Hidden Biodiversity Hotspots in Need of Protection. In the introduction, coalition coordinator and study co-author Daniel Wagner discussed the important role played by coral in marine environments.

“Coral reefs are widely regarded as some of the most biodiverse and productive ecosystems on Earth,” added Wagner. “Often referred to as the rainforests of the sea, coral reef ecosystems account for nearly one-quarter of the total marine biodiversity, despite only covering 0.2% of the total seafloor by area.”

The new study recorded hundreds of deep-sea reefs located between 200 and 1,200 meters below the surface. While sunlight in the deep ocean varies, it rarely significantly penetrates beyond 200 meters, and the majority of the discovered reefs sit in darkness.

In a press release published by U.S. nonprofit Conservation International, Wagner also said: “People often think of the high seas as ocean deserts. In these remote high seas areas, there is actually a lot of diversity, including coral reefs, which are some of the most biodiverse ecosystems on Earth.”

Coral reefs are some of the most “biodiverse and productive ecosystems on earth.” | Alexis Rosenfeld via Getty Images

Are deep-sea coral reefs in danger?

The survival of deep-sea reefs is highly dependent on the stability of the deep ocean. They are extremely vulnerable to ocean warming and other disruption, including that of deep-sea mining. Companies around the world are increasingly emphasizing deep-sea mining in the search for materials such as silver, gold, diamonds, copper, cobalt, zinc, and more.

In the future, smartphone, laptop, and tablet production may depend on deep-sea mining. Even electric car production heralded as a solution to fossil fuel-dependent transportation, could be dependent on the industry for metal cobalt — a key ingredient in batteries. Thus far, formal regulations for ocean mining have never been comprehensively established.

According to the new study, marine protected areas (MPAs) include just 1.2 percent of the high seas. Additionally, protections prevent bottom fishing in just 0.61 percent and deep-sea mining and exploration in 0.41 percent.

In contrast to their limited legal protections, the high seas contain nearly 90 percent of all ocean biomass. They also produce almost 50 percent of the oxygen we breathe and capture 1.5 billion tons of carbon dioxide (CO2) every year.

Typically, many of the species, including coral reefs, that survive at significant depths are slow-growing and long-lived. This means that it could take thousands to millions of years to recover from any damage.