Unomia, the Killer Coral that Suffocates Reefs Off Venezuela’s Caribbean Coast

The highly invasive Unomia species is spreading quickly, raising worries it will stifle marine biodiversity

Unomia Coral puts Venezuelan coastline at risk.
By Camille Rodriguez Montilla
May 13, 2023 | 02:27 PM

Bloomberg — In the early 2000s, people in northern Venezuela say, a man tried to grow and commercialize a coral species for decorating aquariums.

It turned into an ecological disaster.

The pinkish-white, long-tentacled coral — Unomia stolonifera — is extremely invasive. It has now colonized 60 miles of Venezuela’s Caribbean coastline and approximately 1.2 million square miles of the sea floor in Mochima National Park, where it’s wreaking havoc on marine habitats and other coral species.

In the small town of Valle Seco, in Anzoátegui state, local fisherman Celestino Caguana sat on a boat one recent day and repaired the holes in a net by hand. Celestino said he’s been a fisherman his whole life and has never seen as few fish as now.

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“During this time of the year I used to be able to catch octopus here ashore, but not anymore,” he said, because of Unomia. When he goes out to fish he has to go farther away, and each time he has to clean his nets to avoid spreading the foul-smelling coral, which can grow from fragments.

Marine biologist Juan Pedro Ruiz-Allais is the founder of the Unomia Project, a nonprofit initiative to research the coral and stop its spread. He says he discovered Unomia in the Mochima area in 2007 while diving. Ruiz-Allais realized it was covering great expanses of reef at a fast pace and killing other corals.

It wasn’t until 2014 that he managed to classify the species with the help of a fellow marine biologist from the University of Tel Aviv in Israel. (Venezuela didn’t have the laboratories needed to process the samples.) Today he estimates that 80% of the corals in the area are Unomia, which is native to the Indo-Pacific, and only 20% are native to the Caribbean.


How Unomia Disseminates?

Unomia is very hard to eliminate. It has to be cut off from the root, and an expert diver needs about one hour per 10 square feet to do that. “If you divide a fish in two, it’s dead. If you divide Unomia in two, you have two, in three, you have three, and so on,” said Ruiz-Allais.

Ruiz-Allais says that Unomia is mostly disseminated through fishermen’s nets and the anchors of boats. That could hasten its spread, since there is a major port near the park, as well as one of the main industrial refining complexes in oil-producing Venezuela, where vessels sail to transport crude.

Mariano Oñoro, a coordinator with the Unomia Project, says the infestation has led to diminished fishing activity in a region where many people feed themselves off what they can catch. “It’s an issue of food security and economic activity,” he said.

Venezuela is in the heels of one of the deepest economic contractions in modern history, including years of out-of-control inflation and massive shortages of food and medicine. It ranks as the most undernourished nation in South America, with about 23% of the population, or 6.5 million people, unable to access sufficient meals, according to the most recent data from the World Health Organization.


Working with their own funds, Ruiz-Allais and Oñoro have tried to map the extent of the problem, but they lacked the resources to survey three out of the four states where the coral is present. They worry that Unomia could seriously impact the biodiversity of the Caribbean Sea, and say that presentations to local officials have been ignored.

“It seems like no one cares,” said Ruiz-Allais, “but the truth is that no one knows what to do.”

Venezuela’s ministries of Ecosocialism and Information and Communication didn’t respond to a request for comment.

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Academic researchers are trying to understand the phenomenon. Ecologist Estrella Villamizar of the Central University of Venezuela started studying the invasion in 2020 and in February started a project in collaboration with the University of the Andes and the Venezuelan Institute of Scientific Investigation. Villamizar says the priority is establishing a solid base of science before determining what action should follow. The project initially received funding from Larkinven, a private company; now it’s funded by the Venezuelan Ministry of Science and Technology.

Fifteen investigators from the three institutions will evaluate the density, growth, reproduction and chemical composition of the coral for at least a year and a half. Villamizar says the invasion shouldn’t spread much more in that time.

The researchers are focusing not on Mochima but on less affected areas in Aragua state and the Cuare refuge in Falcón state. Addressing the scope of the problem in Mochima would “require much more effort and funds,” according to Villamizar.

Ruiz-Allais grew up diving and swimming among the fish and the native corals of Anzoátegui. He has a young son who he sometimes takes to dive, but there is little biodiversity to see.


“This is worse than an oil spill,” he said. “You can clean up oil, but what do you do about this?”

--With assistance from Patricia Laya