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Replanting coral could restore ecosystems damaged by BP oil spill

Corals are often the only three-dimensional structure in deep water, providing organisms with shelter and a place to feed. Photo: Howard Lasker


Published September 20, 2023

“This is the first step: basically taking animals from Point A and returning them to Point A. ”
Howard Lasker, professor emeritus
Department of of Geology,

A UB coral scientist gardened this past spring on the Gulf of Mexico sea floor.

Researchers from UB, the University of Rhode Island and the National Oceanic and Atmospheric Administration (NOAA) spent 10 days on a research vessel off the Florida coast, where they used a remotely operated underwater vehicle (ROV) to bring fragments of soft, tree-like corals to the surface, and a device they dubbed an “elevator” to lower them back down to the mesophotic depths.

The project, supported by NOAA, was the first outplanting effort to restore coral communities damaged by the Deepwater Horizon oil spill, considered one of the worst environmental disasters in history. Artificial propagation — planting fragments of existing plants to produce new ones — could replace coral lost due to the 2010 spill and provide more habitat for marine life. 

Although the planting site was not directly impacted by the spill, this pilot experiment will help scientists perfect their techniques and learn more about this understudied species’ ability to adapt.

“This is the first step: basically taking animals from Point A and returning them to Point A,” says Howard Lasker, professor emeritus of geology, College of Arts and Sciences, and co-principal investigator on the project. “But the end goal is to move them across greater distances and lower depths to the habitats that were impacted by the oil spill.”

The early results have been positive: The outplanted coral are surviving at rates above average for octocorals.

“We still have to see how they will look in two years, but our experience tells us that most mortality occurs within weeks of transplantation, and then you have slow natural mortality,” says the other co-principal investigator, Carlos Prada, assistant professor of biological sciences at the University of Rhode Island. “These results are encouraging and suggest that these mesophotic ecosystems, despite the oil spill’s detrimental effect, are resilient and capable of maintaining healthy corals and fish populations.”

The crew of the Point Sur research vessel prepares to lower racks of octocoral fragments into the depths of the Gulf of Mexico via their “elevator” device. Photos: Howard Lasker

A ride on a deep-sea elevator

Corals provide critical habitat for fish and tiny invertebrates to survive. They are often the only three-dimensional structures in deep water, providing organisms with shelter and a place to feed. 

“In shallow water, that role is shared with stony corals,” Lasker says, “but in deep water, it's often the octocorals, sometimes called gorgonians, that are creating all of that physical structure.”

Following Deepwater Horizon’s release of 3.2 million barrels of oil, NOAA researchers found deep sea coral was damaged up to 16 miles from the leaking wellhead. The historic, $8.8 billion settlement in 2016 with BP, operators of the Deepwater Horizon oil rig, has paved the way for the restoration efforts. The most direct way to restore the habitat, according to NOAA, is to facilitate new growth of coral species.

Lasker, who has been studying coral for over four decades, was approached about the outplanting effort by Peter Etnoyer, a marine biologist with NOAA’s Coastal Center for Environmental Health and Biomolecular Research and one of the project managers of the coral propagation component of NOAA’s efforts.

Along with Lasker and Prada, about a dozen scientists in May ventured six hours off the coast of Pensacola, Florida, aboard the R/V Point Sur, a research vessel operated by the University of Southern Mississippi.

A command station of monitors on the Point Sur research vessel allowed scientists to watch as the remotely operated underwater vehicle collected and later replanted octocoral fragments along the Gulf of Mexico sea floor, about 230 feet below the surface.

The scientists watched on large monitors as the Beagle, an ROV owned and operated by Marine Applied Research and Exploration, descended into the water and collected fragments of three octocoral species — Thesea nivea, Muricea pendula and Swiftia exserta — from healthy colonies. 

Once the fragments were back on the Point Sur, Lasker and Prada further divided them and affixed approximately 200 fragments to custom-made racks. The racks were returned to 230 feet below the surface via a deep-sea elevator designed by NOAA’s Southeast Fisheries Science Center. The ROV was deployed again — this time to remove the racks from the elevator and strategically place them along the sea floor. 

“The ROV can spend all day on the bottom of the ocean, whereas divers are very limited in the amount of time they can spend at those depths,” Lasker says. 

At the end of July, a team of divers returned to the site and took photographs. They found that 95% of the corals planted in May had survived and appeared healthy. The baseline natural survival rate of these kinds of octocorals is 92% per year.

“So that aspect was very, very successful,” Lasker says. “Now the next step is seeing how well they grow. Hopefully, we will have some numbers and new images in about a year.”

Scientists aboard the Point Sur Research vessel watched on large monitors as racks of octocoral were lowered onto the Gulf of Mexico sea floor. A remotely operated underwater vehicle then replanted the fragments. Photos: Howard Lasker

Temporary move to aquariums

In shallower waters, the warming of the world’s oceans has seriously damaged corals. The nation’s heatwave this summer forced NOAA and other organizations to temporarily move coral from Florida coastlines into temperature-controlled labs.

It’s a tactic that could become more common in the future. Lasker says some scientists believe large numbers of corals should be moved into aquariums, like an endangered species in a zoo, until ocean conditions improve. 

He says he hopes it won’t come to that, and that efforts like their propagation experiment can keep coral in its natural habitat. 

“Are there things we can do to remediate the effects? Is it possible to identify corals that are genetically more resistant to heat stress and propagate those? Can we breed corals to be heat resistant?” he says.

In the long term, Lasker says we have to change the course of climate change, but in the short term, “Some people argue that we have to throw everything on the wall and see what sticks.”