Researchers using high-resolution sonar, underwater drones, and deep-sea cameras have rediscovered a living mesophotic coral reef off the coast of Benin in West Africa, sixty years after initial fishing surveys presumed the deep-water formation was dead.
Sixty Years in the Archives: How a Brief Paragraph Led to Rediscovery
In the 1960s, fishing surveyors off the coast of Benin hauled up heads of coral in their nets while assessing fish diversity and potential trawlable seabeds in the sandy-bottomed Gulf of Guinea, as Yale E360 detailed in its coverage of the expedition. The original researchers shrugged off the discovery, burying the find in a brief paragraph within a report that spanned over 130 pages. With no subsequent surveys conducted in the decades that followed, scientists lost track of the location. As mass bleaching events and overfishing slashed the world’s coral reef area by more than 50 percent since the 1950s, local oceanographers assumed any remnants of the reef were long gone.
That changed when Gérard Zinzindohoué, a researcher at the Benin Fisheries and Oceanological Research Institute, reviewed the historical records after seeing coral in Cape Verde in 2021. Realizing a significant gap in local marine knowledge, Zinzindohoué set out to find whether reefs still existed in Benin’s waters. Stringent financial hurdles—including stringing together failed grant applications before securing a $20,000 National Geographic Explorers grant in January 2025—slowly cleared the path toward the water, according to reporting by Yale E360.
Overcoming Logistics and Pirogues to Map the Gulf of Guinea
Mounting the expedition required extraordinary resourcefulness. Because Benin lacks a permanent research vessel, the team had to hire local fishermen to ferry researchers 14 miles offshore aboard wooden pirogues, jury-rigging the boats to tow high-tech sonar equipment, Yale E360 reported. The gear itself nearly caused the project to stall when a European supplier refused payment from an African bank account, and the sonar equipment alone swallowed nearly 80 percent of the grant budget.
“It was not an easy field campaign. 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.”
Gérard Zinzindohoué, Benin Fisheries and Oceanological Research Institute, via Frontiers
After navigating repeated engine failures and months of rigorous fieldwork, the sonar finally picked up strong rocky echoes beneath the seafloor, noted Yale E360. National Geographic dispatched its Exploration Technology Lab deep-sea camera system to investigate, allowing the team to film the bottom while their pirogue bounced atop offshore swells, according to Yale E360.
What the Underwater Drones and Deep-Sea Cameras Discovered
Rather than forming a single continuous barrier, the reef consists of scattered coral patches growing across rocky outcrops in the ocean’s dimly lit twilight zone, Scientific American explained.
Photo: Frontiers
The rediscovery, published in Frontiers in Marine Science, marks the first confirmed living mesophotic coral ecosystem on the Gulf of Guinea’s continental shelf. The underwater drone and trail cameras captured six types of soft coral, two black corals, and eight species of reef-loving fish sheltering around the formations, according to Frontiers.
Marine Life Category
Observed Species / Taxa
Soft Corals (Octocorals)
Six types
Black Corals
Two types
Associated Reef Fish
Golden African snappers, blackbar soldierfish, Guinean angelfish, West African goatfish, Monrovia doctorfish, three-banded butterflyfish, and two damselfish species
Implications for Marine Conservation and Future Expeditions
“Since it’s an undisturbed marine ecosystem, it can help through carbon dating or paleoclimatic study to tell us which kind of climate system has occurred here in the past. It’s better to know the past to help explain the present, and help know which kind of direction we can take in the future.”
Photo: Yale E360
Gérard Zinzindohoué, project lead for Coral Reefs Rediscovering & Exploration in Benin, via Yale E360
Because physical coral samples have not yet been extracted, scientists emphasize that species identifications require direct sampling confirmation, Frontiers reported.
