Benin’s presumed-dead coral reef rediscovered teeming with life

A deep-water coral reef that vanished from the scientific record more than half a century ago has resurfaced and – in a dramatic twist of fate, has been found thriving. 

Surveys conducted in the 1960s – aimed at charting productive fishing grounds off Benin – picked up hints of a possible reef structure but concluded it was almost certainly dead. Now, armed with modern sonar and the Deep Sea Camera System supplied by the National Geographic Exploration Technology Lab, researchers have confirmed the reef not only survived, but appears to be flourishing.

“It was not an easy field campaign,” said Gérard Zinzindohoué of the Institut de Recherches Halieutiques et Océanologiques du Bénin, lead author of the study published in Frontiers in Marine Science. “It was a mix of long days at sea, technical problems and a lot of uncertainty. But then we saw structures on the sonar that looked like they could be reef signatures, which gave us hope that we were close.

Next, the team surveyed the structures with an underwater drone and the Deep Sea Camera System. 

“That was a big moment for us, because suddenly we could actually see the seafloor,” continued Zinzindohoué. “I still remember seeing those first images. It was a mix of excitement and disbelief, because after all this time thinking about this reef, suddenly there was something real in front of us.”

The original 1960s surveys had located a possible reef more than 50 metres (164 feet) below the surface, yet had written it off as dead. Decades later, Zinzindohoué and his colleagues suspected that rather than dead, this might be a mesophotic coral ecosystem – a type of reef system that behaves nothing like its shallow-water cousins.

“A mesophotic coral ecosystem lives deeper than the usual shallow coral reefs, in zones where light is much more limited,” Zinzindohoué explained. “Unlike typical shallow reefs, it does not always form a single continuous reef structure. Instead, it can appear as patchy or scattered coral communities spread across the seafloor.”