🐠 Coral believed extinct rediscovered after 24 years in Galápagos

• Scientists have rediscovered over 250 healthy colonies of the coral species Rhizopsammia wellingtoni in waters around the Galápagos Islands.
• The coral had not been observed by researchers since 2000 and was classified as critically endangered and possibly extinct in 2007.
• Many of the corals had budding polyps, indicating they are actively reproducing.

Discovery during other research

Scientists have rediscovered a coral species they believed had died out. They found it in waters around the Galápagos Islands for the first time in 24 years.

In the journal Marine Biology, biologists describe how they found over 250 healthy colonies of Rhizopsammia wellingtoni. It is a black stony coral that was last officially documented by researchers in 2000.

The team rediscovered R. wellingtoni while diving south of Tagus Cove off Isabela Island in January 2024. They were searching for a new species of sea slug when they stumbled upon over 100 colonies of the elusive coral on a rocky reef 12 meters below the surface.

Many of the corals had budding polyps. This indicates they are actively reproducing according to the California Academy of Sciences.

More colonies discovered

Later, the researchers conducted additional surveys and found even more colonies. They discovered two more sites off Isabela Island and one off Fernandina Island. At one location, Cabo Douglas, R. wellingtoni had never been observed before according to the Charles Darwin Foundation.

The scientists found R. wellingtoni in two different color combinations: black-purple and red-black.

Unique species from Galápagos

R. wellingtoni is found only in the Galápagos Islands. The volcanic archipelago is located approximately 965 kilometers from mainland Ecuador in the Pacific Ocean. The first specimen of this coral was collected for scientific study in 1974. The species was named in 1982 to honor its original discoverer Gerard M. Wellington, a biologist at the University of Houston.

The species is a solitary coral. This means each polyp lives independently within its own skeleton, rather than as a group sharing the same skeleton. Individual R. wellingtoni polyps are also small, so the colonies are small. They are typically less than 1.3 centimeters wide. Together, these characteristics make R. wellingtoni easy to overlook.

Survival in deeper waters

Historically, these corals lived in the cool, shallow waters around Galápagos. There, temperatures typically range from 15 to 26 degrees Celsius. However, after the 1982-1983 El Niño warming event, R. wellingtoni experienced sharp population declines. It was rarely observed during surveys after this.

In 2007, the International Union for Conservation of Nature classified the coral as critically endangered and possibly extinct.

More than two decades later, scientists are pleased that R. wellingtoni has not disappeared entirely. They believe the species survived the severe 1982-1983 El Niño by colonizing deeper sites where the water was cooler. Then, the recent 2020-2023 La Niña likely helped cool the ocean. This allowed R. wellingtoni to once again inhabit shallower areas.

Using remotely operated underwater vehicles, the scientists confirmed the species lives in deeper water. It inhabits the mesophotic zone, between 30 and 150 meters below the surface.

Advantages without symbiotic algae

This makes sense because R. wellingtoni does not rely on photosynthetic algae. This means it can survive in low-light conditions. Many other species have a symbiotic relationship with algae that live in the coral's tissues and supply components of sugars and proteins. To keep their photosynthesizing algae alive, these species need to be closer to the surface where plenty of sunlight can penetrate the water.

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