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Story Publication logo May 5, 2024

Why Some Corals are Better Off Dead

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Coral reef
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The catastrophic effects of Unomia Stolonifera

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Fire coral is engulfed by Unomia stolonifera at Cachicamo Island in Mochima National Park on November 22. Image by Ana María Arévalo Gosen/The Washington Post. Venezuela.

As scientists rush to save ailing corals elsewhere, in Venezuela locals are trying to kill off this stinky variety.


VALLE SECO, Venezuela — Estrella Villamizar grabbed the soft red and white coral by its stem and hacked it off with a blow of her wooden knife before tossing it in a bucket with other pieces she’d already ripped out of the Caribbean waters lapping against this deserted beach.

On the sea bed, stretching for a distance as far as the eye could see, a blanket of the dark coral swayed in the warm current.


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As ocean temperatures reach record highs, scientists elsewhere have been rushing to save reefs, moving coral to land nurseries to preserve it and dreaming up novel ways to cool it off at sea. But here in Venezuela, reefs face a different kind of lethal threat: Unomia stolonifera, an invasive coral species that is smothering native varieties.

Hailing from Indonesia, the slimy cauliflower-looking coral has expanded across the shores of four states in Venezuela, covering at least some 1,000 square miles.

“At this point, it is almost certain that it will invade the entirety of the Caribbean,” says Villamizar, a tropical ecology professor at the Central University of Venezuela.


Estrella Villamizar, left, a researcher at the Tropical Zoology Institute of the Central University of Venezuela, and Maria Cristina Goite, a chemist from the Venezuelan Institute of Scientific Research, submerge into Cepe Bay, on November 6. Image by Ana María Arévalo Gosen/The Washington Post.
Unomia stolonifera carpets the seabed off the coast of Valle Seco in Aragua, Venezuela. Video by Camille Rodriguez Montilla.

Villamizar, right, and Goite measure the growth rate of the Unomia stolonifera coral on November 8 in Valle Seco, Choroní, the primary focus of the Unomia stolonifera invasion in Aragua, Venezuela. Image by Ana María Arévalo Gosen/The Washington Post.

She is part of a team of biologists, chemists, villagers, and entrepreneurs fighting to keep Unomia at bay. It’s a battle they’re waging with limited tools. Years of economic duress have hollowed out the Latin American country’s research centers. Government budgets to do this kind of work, meanwhile, are nonexistent. So they have to come up with out-of-the-box approaches, from creating underwater hacking machines to finding ways to turn the slimy coral into a usable product, making its harvesting a profitable business.

If left unchecked, Unomia could decimate local reefs and the animals and plants that depend on it.

Already, it’s devastating local villages. Fishers report that last year was one of their worst. Israel Sosa, a longtime fisherman in these waters, says his haul has dropped from about 33,000 pounds of Albacore fish in a 48-hour shift just a few years ago to closer to 220 pounds.

“If it kills the native coral, it would completely end the coast’s life,” says 55-year-old César Jove, who spends his afternoons cleaning the beach for tourists about 310 miles away, where Unomia made its first appearance more than a decade ago.


Fishermen work on November 10 at the Guayamure fishing point, which is a 15-minute boat ride from Puerto Colombia. The livelihoods of these fishermen and their families are tied to fishing, which has seen a noticeable decline in the past year. Image by Ana María Arévalo Gosen/The Washington Post. Venezuela.

Ground zero

Marine biologist Juan Pedro Ruiz-Allais was the first to spot Unomia in 2007 inside Mochima National Park in northeastern Venezuela, where he spent most of his childhood. As soon as he spotted the tentacle-looking stems, he realized it was not a native species.

According to local fishermen, an aquarist allegedly introduced the coral to the area, hoping to harvest it and sell it as fish tank decoration. In its native Indonesia, Unomia has natural predators, such as sea slugs, that keep it in check. But without a natural predator outside of the Indo-Pacific, it’s spiraled out of control in Venezuela, Ruiz-Allais said.

Surveys he conducted along with other researchers showed Unomia taking over other species of coral and seagrass beds that serve as food sources and nurseries for fish and other animals. Some of these areas were already battered by overfishing and pollution.

Ruiz-Allais also found the invasive coral has proved to be more resilient than its native counterparts, thriving in a much broader range of temperatures and light.

The researcher said he alerted the government of the invasive species years ago but didn’t get a response.

The Ministry of Ecosocialism did not respond to a request for comment. Several people familiar with the matter said the government has barred researchers who depend on it for funding from talking about Unomia.


Mariano Oñoro, a coordinator with the Unomia Project, teaches students at the Don Bosco school in Barcelona about the danger and risk of the invasive coral on November 21. Image by Ana María Arévalo Gosen/The Washington Post. Spain.
Fishermen pull in nets off the coast of Choroni, Venezuela, where the invasive Unomia coral has disrupted local fishing. Video by Camille Rodriguez Montilla.

Children play on a newly installed pier at Chichiriviche de la Costa, a beach in Venezuela that has not yet seen Unomia coral. Image by Ana María Arévalo Gosen/The Washington Post.

So Ruiz-Allais created a nonprofit, the Unomia Project, that has focused on educating citizens on how to identify the invasive coral and prevent it from spreading. They advise fishers to clean their nets and beach goers to wash bathing suits and diving gear that came into contact with Unomia.

Their budget, made up mostly of donations, hasn’t stretched far enough to cover a full-fledged census of the invaders, never mind eradicating them.

Based on the group’s observations, Ruiz-Allais calculates that more than 100 kilometers — or more than 60 miles — of shore, and about 8 million square meters — three square miles — of seabed are covered by Unomia in Mochima National Park alone.

Now, Ruiz-Allais fears that Venezuelan oil vessels are transporting the invasive coral to Cuba, where it started showing up last year, according to Cuban marine biologist José Espinosa Sáez.

In Valle Seco, some locals who depend on fishing and tourism have taken to ripping it out by hand using makeshift wooden knives.

Aside from looking like a slobbery dark carpet, Unomia has a strong rotten fish smell. “It’s disgusting, sometimes even the fish smell like it and you have to wash them with lemon and vinegar to get rid of the stench,” Jove said, adding that the coral also puts off tourists.

But locals’ efforts could backfire. The small pieces of Unomia left behind can grow into a new colony, said Mariano Oñoro, a coordinator with the Unomia Project.


Unomia spreads by entangling itself in fishing nets upon reaching the seabed. When fishermen lift the nets with the coral and relocate them to another fishing spot, it descends and proliferates in the new area. Image by Ana María Arévalo Gosen/The Washington Post.

A coral gun

To avoid that problem, Jorge García, an industrial designer and boat captain, has been working on developing machines to help save native corals.

On a recent afternoon, García aimed his contraption, an ultrasound gun, at a cluster of Unomia growing on a native coral. After he pulled the trigger, an ultrasound wave unmoored a cluster of the invasive species before García sucked it up with another machine, releasing a strong fishy smell.

García became involved in the quest to fight Unomia after learning about its devastating effects from Ruiz-Allais and his team. Given his background as an industrial designer specializing in machine building, he decided to come up with better ways to remove Unomia.


Jorge García navigates his 24-foot inflatable boat. As the founder of Unomia Solutions, he develops machinery to combat Unomia in Mochima National Park. Image by Ana María Arévalo Gosen/The Washington Post. Venezuela.
Jorge García uses his ultrasound gun to cut off Unomia growing on a native coral in Anzoategui, Venezuela. Video by Camille Rodriguez Montilla.

Fragments of the Unomia coral were detached after being targeted with an ultrasound gun created by García. Another machine then sucks up the coral. Image by Ana María Arévalo Gosen/The Washington Post. The Washington Post.

García, who owns a vessel rebuilding company, Grenyachts, also had the funds to do it, overcoming another major obstacle in fighting Unomia. So far, he has spent almost $1 million out of pocket, which he expects to make back by renting out the machinery to international organizations and governments that may want to remove Unomia in the future. That includes Venezuelan officials, who already granted him permission to carry out some of his research.

With his current setup, he can clean one square meter, or around 10 square feet, of Unomia-covered native coral in one minute, compared to the hour or more it would take a professional diver to do it.

“This is a fight for decades, generations,” he said.


Biologist Jesús Subero dives near a seabed teeming with Unomia in November in Mochima National Park, a hotspot for this coral invasion. Image by Ana María Arévalo Gosen/The Washington Post.

An invasive business

Meanwhile, Project Coralien, a group of marine biologists and chemists that has received some government funding to research Unomia, is looking at another way of overcoming the lack of funds. The group is trying to find a commercial use for the coral, so harvesting it becomes a business.

One idea is to make it into a waterproofing material or a fluorescent material similar to rhodamine, a dye used in biotechnology. So far, these ideas seem promising, but to test them out, the team needs a molecular magnetic resonance imaging machine to separate Unomia’s chemical compounds and determine their specific uses.

Rubén Machado, who heads the atomic energy department at the Venezuelan Institute for Scientific Research, remembers a time when the country had seven such machines. Now they have none. Once the government defunded research institutions, the equipment was not maintained and became obsolete. Looters vandalized and damaged one of the machines.

Replacing the equipment is expensive — and complicated. Foreign companies are subject to sanctions when doing business in Venezuela, so its makers are reluctant to sell it to the researchers. Álvaro Álvarez, Project Coralien’s chief chemist, wrote a letter to the United Nations authorities who oversee sanctions, asking for an exception. So far, he has received no answer.

Machado says his group will keep trying because he believes making Unomia profitable is the only way to eradicate it.

“The possibility is there,” he said. “But we need to be able to prove it.”

Project Coralien studies Unomia stolonifera in its lab to research commercial uses for the invasive coral. Video by Camille Rodriguez Montilla.

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