Release Date: September 21, 2023
BUFFALO, N.Y. — A nascent effort to rebuild deep-sea corals damaged by the Deepwater Horizon oil spill is showing signs of early success, according to researchers handling the operation.
The National Oceanic and Atmospheric Administration (NOAA)-funded work, which began this past spring, involves submersing a remotely operated vehicle (ROV) 230 feet deep to the Gulf of Mexico seafloor.
An operator aboard a research vessel uses the ROV to gather coral fragments and bring them to the surface. From there, researchers cut the fragments into pieces – a technique known as vegetative propagation, which allows the researchers to generate many colonies from a small number of source colonies.
The new pieces are then placed on racks and lowered back down to the seafloor using a short, four-legged platform dubbed the “elevator” by researchers. The ROV rendezvous with the elevator, and an operator removes the racks and places them on the seafloor.
“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,” says Howard Lasker, PhD, professor emeritus of geology in the University at Buffalo College of Arts and Sciences and a co-principal investigator on the project.
Lasker is working alongside colleagues from the University of Rhode Island and NOAA, which is funding the endeavor from the $8.8 billion settlement between BP and the U.S. government.
Although last May’s planting site, about six hours off the coast of Pensacola, Florida, was not directly impacted by the 2010 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,” Lasker says. “But the end goal is to move them across greater distances and lower depths to the habitats that were impacted by the oil spill.”
Thus far, the early results have been positive: The outplanted coral are surviving at rates above average for octocorals. In July, divers found that 95% of the soft, tree-like corals planted two months prior had survived and appeared healthy. The baseline natural survival rate of these kinds of corals is 92% per year.
“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, PhD, assistant professor in the Department of Biological Sciences at the University of Rhode Island.
He adds: “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.”
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. Corals were coated in a clumpy brown material containing petroleum and the diversity of invertebrates took a nosedive. Altogether, more than 770 square miles of deep-sea and mesophotic — or low light – habitats were injured by the oil spill, according to NOAA.
In shallower waters, the warming of the world’s oceans through climate change has also seriously damaged corals. This summer, the nation’s heatwave 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.”