Corals thought to be dead were found alive 60 years later
Live corals have been discovered off the west coast of Africa; their existence had not been confirmed for over 60 years. Underwater cameras have revealed that an entire coral garden has survived at a depth of 54 metres, where fish feed and take shelter.
Research carried out in 1963–1964 first suggested the existence of a possible reef off the coast of Benin. At the time, scientists did not have access to modern equipment and assumed that the deep-water corals were most likely dead.
This new discovery does not mean that the lost ecosystem has ‘come back to life’. The researchers do not know what condition the corals were in during the 1960s. It is possible that the previous assessment was incorrect and that the coral garden has remained alive all this time.
Details
Scientists revisited old reports compiled during surveys to identify promising fishing grounds. These reports mentioned structures resembling a coral reef stretching along the coast of Benin in the Gulf of Guinea.
From April to December 2025, the researchers surveyed the seabed using a side-scan sonar. The device emits sound waves and, based on the nature of the echoes, can distinguish soft seabed sediments from rocks and other solid objects.
The team surveyed around 11.5 kilometres of seabed and identified two areas with unusually strong echoes. These areas could turn out to be rocky formations suitable for coral growth.
An underwater vehicle and a deep-sea camera, provided by the National Geographic Technology Lab, were then deployed to the most promising sites. The footage obtained allowed the area to be viewed directly for the first time.
At a depth of around 54 metres, the researchers observed living coral communities. These were situated in separate groups on the rocky seabed rather than forming a continuous reef.
Based on the images, the scientists have provisionally identified at least eight different species of coral: six types of octocoral and two groups of black coral. Octocorals usually have a more flexible skeleton than the reef-building stony corals familiar from photographs of tropical reefs.
Eight species of fish were discovered nearby. These included golden African snappers, Guinean angelfish, West African barracudas, three-striped butterflyfish and several species of damselfish. The corals provide them with shelter and a feeding ground.
The authors describe the ecosystem they found as mesophotic. Such communities are found in the twilight zone of the ocean: sunlight still penetrates there, but there is significantly less of it than at the surface.
Not a reef, but a coral garden
Despite the study’s title, the area discovered does not resemble a typical coral reef with a robust limestone base. It consisted mainly of octocorals, growing in separate groups on suitable patches of the rocky seabed.
It is therefore more accurate to refer to it as a mesophotic coral garden. The researchers found no evidence to suggest that they were looking at a continuous barrier reef.
Historical records suggest that the presumed coral zone may have stretched along the coast for approximately 40 kilometres. However, the recent expedition surveyed only a small part of this area and carried out a limited number of surveys. The possible continuation of the coral garden has yet to be found.
The scientists have not yet taken any samples either. Coral species were identified from video footage, so their exact taxonomic classification will need to be confirmed during the next expedition.
The overall condition of the ecosystem is also unknown. The presence of living corals and fish does not yet allow us to describe it as fully healthy: to do so, we need to measure the coverage area, colony density, growth rates, age and signs of possible damage.
Why this is important
This is the first video-confirmed evidence of the existence of living mesophotic coral communities off the coast of Benin. According to the authors, no similar findings have previously been described on the continental shelf of the Gulf of Guinea.
Deep-water coral gardens create a complex habitat in areas where the seabed would otherwise be relatively flat. Fish and invertebrates can hide, feed and reproduce amongst the corals.
However, their deep location does not guarantee safety. Such ecosystems may be threatened by fishing gear, resource extraction, pollution, sedimentation and changes in ocean temperature.
Without an accurate map of the coral garden, it is difficult to take it into account when planning fishing and other offshore activities. New research provides the initial data needed for further monitoring and the potential conservation of the site.
Background
Shallow-water coral reefs are relatively easy to study using divers and satellite imagery. Mesophotic communities are found at greater depths, so locating them requires sonar, remotely operated vehicles and specialised cameras.
Particularly few such studies have been carried out off the coast of West Africa. Therefore, a lack of information about corals does not necessarily mean that they are not present there. Many areas of the seabed have simply never been surveyed using modern methods.
The story behind the discovery off Benin highlights the value of old scientific archives. Even brief expedition records from the mid-20th century can point to where to look for poorly studied ecosystems.
The authors suggest that other undocumented coral gardens may exist off the coast of West Africa. However, it is not yet possible to extrapolate this new discovery to the entire region: each suspected site must be investigated directly.
Source
The study by Koffi Gérard Franck Zinzindohoué and his colleagues, ‘First evidence of live mesophotic coral reefs on the Benin continental shelf’, was published in the journal Frontiers in Marine Science in 2026.