Hakai Magazine

Coastal science and societies

Keepers of the Deep

Using specialized breathing equipment, a brave team of researchers dives into the ocean’s twilight zone to protect its little-known reefs.

Authored by

by Alex Goetz and Justin Grubb

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As marine scientist Luiz Rocha and his team of divers descend to depths of around 150 meters below the ocean surface, they enter a unique ecosystem of mesophotic reefs. The team, from the California Academy of Sciences, is one of only two in the world diving to what’s known as the ocean’s twilight zone.

This deepwater region is home to cup corals, peppermint angelfish, harlequin grouper, giant sea fans, benthic ctenophores, and more. But this alien world is in danger of disappearing. The vast majority of marine protected areas (MPAs) stop at the 30-meter depth line, leaving the mesophotic region out in the cold. In some areas—Brazil’s MPA, Fernando de Noronha, for example—75 percent of the shallow reefs are protected, and 100 percent of the deeper reefs are not. And yet, much of the fishery is concentrated in the deeper waters.

So how can we protect these amazing deepwater reefs if they remain largely unknown to most people? That’s the challenge Rocha set for his team with the mission called Hope for Reefs—a global initiative launched in 2016 led by the California Academy of Sciences to research and restore critical coral reef systems in the twilight zone. By bringing attention and awareness to these ecosystems through their photos, videos, and collections of new and undescribed species, they’ve already helped create two marine protected areas, one in Brazil and the other in the Philippines.

Follow Rocha and the team on two technical dive expeditions in 2019 as they descend well beyond the reaches of normal scuba diving in the Marshall Islands and then in Rocha’s home country of Brazil to save these reefs before it’s too late.