A coral reef off the coast of West Africa, once believed to be dead, has been rediscovered and found to be “teeming with life.” Scientists utilized sonar technology and underwater drones to locate the thriving ecosystem deep within the Gulf of Guinea.
Initial surveys conducted in the 1960s, which were primarily aimed at identifying potential fishing grounds, had noted the possible existence of a deep-water coral reef. However, researchers at the time concluded that the reef must have perished. Modern exploration, employing a contemporary sonar survey and the Deep Sea Camera System from the National Geographic Exploration Technology Lab, has revealed what appears to be a healthy reef.
The discovery, detailed in the journal Frontiers in Marine Science, was the result of a challenging field campaign. Lead author Gérard Zinzindohoué described the effort as involving “long days at sea, technical problems, and a lot of uncertainty.” The breakthrough came when sonar readings indicated structures consistent with reef signatures, providing a critical sign of hope.
Subsequent investigation with an underwater drone and the deep-sea camera system allowed scientists to directly observe the seafloor. Zinzindohoué recalled the “big moment” of seeing the first images, describing a mix of excitement and disbelief at encountering a tangible reality after years of speculation about the reef’s existence.
The historical surveys had placed the potential reef at depths greater than 50 meters (164 feet) and presumed it to be inactive. Zinzindohoué and his colleagues at the Institute of Halieutic and Oceanographic Research in Cotonou, Benin, theorized that it could be a mesophotic coral ecosystem. These ecosystems exist in deeper, dimly lit waters and do not always form continuous structures, often appearing as scattered coral communities across the seabed.
Following the historical data, the research team surveyed seven miles of the seabed using sonar, identifying two potential reef signals. Deploying an underwater drone equipped with a camera system, they captured footage revealing a seemingly healthy reef. The ecosystem supports eight different types of coral and is home to eight species of fish, including golden African snappers, blackbar soldierfish, Guinean angelfish, and West African goatfish.
While the reef does not appear to be a solid barrier, instead consisting of coral patches on rocky substrates, researchers believe further surveys could uncover additional reefs. This finding represents the first confirmed record of a living mesophotic coral ecosystem on the Gulf of Guinea continental shelf. Zinzindohoué suggested this discovery is likely not an anomaly but an indicator of how much remains unknown about the coastal regions of West Africa and beyond.
Direct coral sampling has not yet been conducted, meaning species identifications require confirmation. It is also unclear whether the corals were indeed dead in the 1960s and have since recovered, or if the initial assessment was inaccurate. The team emphasized the need for further research to better understand this newly found reef and potentially others in the vicinity.
Zinzindohoué stated that the current exploration is initial, noting that historical reports suggested a continuous reef barrier approximately 40 kilometers (25 miles) long. Only a small section was surveyed with limited visual transects. Securing additional funding for a comprehensive scientific diving and sampling program is a priority to gather more information about these poorly understood ecosystems.
Understanding the reef’s history is considered particularly exciting, as it could offer insights into how the ocean in the region has evolved over time, providing a glimpse into a long-undocumented archive.