Invasive Coral Species

An ominous shadow in the turquoise Caribbean waters off Venezuela comes from a deadly intruder – a soft coral that experts say has caused one of the most destructive habitat invasions on record anywhere.

The Unomia stolonifera, native to Indonesia and the Indo-Pacific region, is a pinkish type of pulse coral named for its dance-like movements in the ocean currents. It is a popular aquarium ornament – pretty to look at and hardy – with a single polyp fetching between US$ 80 and 120 dollars.

But it’s also a killer. It settles on native hard corals, rocks and even seagrass, which it suffocates and replaces, ultimately destroying entire ecosystems.

Off Venezuela’s north coast, Unomia dominates the ocean floor landscape after being introduced through the illegal aquarium trade around 20 years ago.

“This is an ecological catastrophe,” says marine biologist Juan Pedro Ruiz-Allais, a Director of Project Unomia, which is named after the invader he has spent years investigating.

He explains that fish stocks are drastically decreasing in the waters off Venezuela as native reefs – which serve as nurseries and feeding grounds – die off. “When the reef dies when it is covered by the Unomia stolonifera, a disruption of the food chain occurs,” says the biologist, noting that it’s a “social, food security and economic problem because the livelihood of fishermen is compromised.”

When Ruiz-Allais came across the invader in 2007, it was an unknown species in the Caribbean and even the Atlantic. It was first spotted in the Mochima National Park – an archipelago covering more than 94,000 hectares – and has since been found to have colonised most of those islands.

From there, it spread west and east in the Caribbean Sea. Off the northern state of Anzoategui, it has taken over the equivalent of 300 football stadiums. The coral is spread by fishing nets, anchors and ship ballast water.

This threat extends beyond Venezuela’s borders – officials say Unomia traces have been found near the islands of Aruba and Curacao, and in waters off Colombia and Brazil where it attached to an oil rig but was controlled.

“It is a problem that will affect the rest of the Caribbean,” says Ruiz-Allais.

But nowhere has it been more destructive than in Venezuela. Fishermen and tour operators who are concerned about the invasive coral’s rapid propagation have resorted to manual extraction. But experts say this is not advised because broken off fragments are transported by the tides, enabling the soft coral to settle to create yet more colonies.

The privately funded Project Unomia has developed an extraction machine with a group of engineers that is awaiting government approval for testing.

The Venezuelean Institute for Scientific Research and Ministry of Eco-socialism launched an investigation into the coral’s rapid spread but have yet to come up with a solution. For now, the magnitude of the problem is such that the invader’s elimination appears impossible.

“What we can do is recover some areas and control it,” says Project Unomia coordinator Mariano Onoro.

MARINE INVASION

An underwater view of the invasive coral Unomia stolonifera proliferating and threatening other coral species on coral reefs at Valle Seco beach, Choroni, Aragua state in Venezuela. A shadow snaking across the beach’s turquoise waters serves as a sign of the explosive spread of the Indo-Pacific soft coral in Caribbean waters, considered by experts to be one of the world’s deadliest marine invasions. It clings to living things, rocks or seabeds and is believed to have been introduced illegally for commercial purposes in Mochima, a paradisiacal marine ecosystem of more than 94,000 hectares between the states of Anzoategui and Sucre.