Researchers used sonar and underwater imaging techniques to find a mesophotic coral backyard that scientists within the Nineteen Sixties had assumed was useless.
Greater than 50 meters beneath the waters off Benin, cameras revealed a coral neighborhood that scientists had as soon as presumed useless. Fishing surveys carried out within the Nineteen Sixties had recognized what gave the impression to be a deep-water reef, however concluded that it was in all probability not alive. A long time later, trendy sonar and the Deep Sea Digital camera System from the Nationwide Geographic Exploration Expertise Lab have proven an apparently wholesome ecosystem.
“It was not a straightforward discipline marketing campaign,” stated Gérard Zinzindohoué of the Institut de Recherches Halieutiques et Océanologiques du Bénin, lead creator of the article in Frontiers in Marine Science. “It was a mixture of lengthy days at sea, technical issues, and lots of uncertainty. However then we noticed constructions on the sonar that regarded like they could possibly be reef signatures, which gave us hope that we have been shut.
“Subsequent, we surveyed the constructions with an underwater drone and the Deep Sea Digital camera System. That was an enormous second for us, as a result of instantly we might truly see the seafloor. I nonetheless keep in mind seeing these first photos. It was a mixture of pleasure and disbelief, as a result of in spite of everything this time excited about this reef, instantly there was one thing actual in entrance of us.”
Previous information information a brand new search
The sooner surveys had recorded a attainable reef at a depth better than 50 meters and judged it prone to be useless. Zinzindohoué and his colleagues suspected as an alternative that the location may comprise a mesophotic coral ecosystem, a neighborhood that survives in deeper water the place far much less daylight reaches the seafloor.
“A mesophotic coral ecosystem lives deeper than the standard shallow coral reefs, in zones the place gentle is rather more restricted,” defined Zinzindohoué. “In contrast to typical shallow reefs, it doesn’t all the time kind a single steady reef construction. As an alternative, it will possibly seem as patchy or scattered coral communities unfold throughout the seafloor.”
https://youtu.be/8OU5oVyVEDc
A video of the reef. Credit score: Gérard Zinzindohoué
Cameras affirm a residing coral neighborhood
Utilizing the historic survey information to slender their search, the scientists mapped 11.5 kilometers of seabed with sonar. They detected two alerts which may characterize reefs, then examined essentially the most promising areas with an underwater drone and the Deep Sea Digital camera System, which functioned very similar to path cameras beneath the ocean.
The footage revealed what gave the impression to be a wholesome reef neighborhood. Researchers noticed eight kinds of coral and eight fish species feeding or sheltering among them. The fish included golden African snappers, blackbar soldierfish, Guinean angelfish, West African goatfish, the Monrovia doctorfish, three-banded butterflyfish, and two species of damselfish.
Rather than forming one continuous coral barrier, the reef appears to consist of separate coral patches growing across suitable rocky areas. Additional exploration could reveal more reefs beyond the limited area surveyed.
More reefs may remain undocumented
“To our knowledge, this is the first confirmed record of a living mesophotic coral ecosystem on the Gulf of Guinea continental shelf,” said Zinzindohoué.
“However, I think what we found is probably not an exception. It is more likely a reflection of how little we still know about coastal regions in West Africa and elsewhere. If we were able to find this reef again after 60 years, how many others are still undocumented or simply forgotten? So yes, I do believe there are likely more coral systems out there that we have not documented yet. But we should not assume they are everywhere. Each discovery needs to be confirmed. Without going back into the field, we are really just guessing.”
Major questions still require fieldwork
The scientists have not yet collected physical samples from the corals, so their species identifications remain unconfirmed. The available evidence also cannot determine whether the reef was truly dead during the 1960s and later recovered, or whether the original surveys misjudged its condition. Additional research will be needed to reconstruct its history and search for other nearby coral communities.
“This is still an initial exploration,” said Zinzindohoué. “The historical reports suggested that this could be a continuous coral reef barrier extending roughly 40 kilometers parallel to the coast. We only surveyed a small section of this area, and we had a limited number of visual transects. If I had all the grant money in the world, the first thing I would do is return to the site with a proper scientific diving and sampling program. These are ecosystems that are still poorly known in this part of the world, and every additional piece of information matters.
For me, the most exciting part is about understanding the reef’s history, and what it can tell us about how the ocean in this region has changed over time. It feels like we have only just started to read an archive that has been there for a very long time.”
Reference: “First evidence of live mesophotic coral reefs on the Benin continental shelf” by Coffi Gérard Franck Zinzindohoué, Houangninan Midinoudéwa, Bôla-Nlé Christelle Akondé, Zacharie Sohou, Ursula Schauer, Björn Fiedler, Kanna Rajan and Jonatha Giddens, 10 June 2026, Frontiers in Marine Science.
DOI: 10.3389/fmars.2026.1848226
This research was funded by the National Geographic Society (Grant No. EC-115084R-24). National Geographic Exploration Technology Lab supported this research by providing access to specialized equipment.
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