Restoration Lab Corals Return to the Seafloor for the First Time

A recent expedition off the coast of Louisiana marked an exciting milestone for the Deepwater Horizon Mesophotic and Deep Benthic Communities restoration projects ! Over the past few years, scientists collected mesophotic corals from the Gulf to contribute to spawning and growth studies in federal and partner labs. These corals will support restoration of habitats injured by the Deepwater Horizon oil spill . This summer, the first round of corals being cared for in these labs returned to the seafloor from NOAA Southeast Fisheries Science Center's lab in Galveston, Texas. Scientists will monitor the corals over the coming years to understand the success of different coral propagation methods.

Returning corals back to the same area where they were collected, after a relatively short period of time in the lab, helps ensure these communities continue to grow and thrive. It also provides spawning stock for lab husbandry efforts and fills crucial knowledge gaps about these species' reproduction and growth rates to support restoration. Mesophotic and deep benthic habitats are areas of the seafloor that see little to no sunlight. They are home to a complex community of fish, corals, and other invertebrates. In the Gulf, more than 770 square miles of these habitats were injured by the 2010 Deepwater Horizon oil spill. NOAA and the Department of the Interior are leading efforts for the Deepwater Horizon Open Ocean Trustees to restore deep-sea communities injured by the spill.

Road Trip from Lab to Ship

Early one morning in Galveston, Texas, NOAA aquarists carefully moved 24 octocoral colonies into insulated coolers for a road trip to Cocodrie, Louisiana. Octocorals are soft corals with flexible, internal skeletons and eight tentacles on each of the individual polyps that make up the coral colony. Many species of octocorals grow polyps in branching shapes. They can be fragmented into separate smaller colonies easily-like clipping off branches of a tree-to propagate. The two species selected for this first homecoming mission were Swiftia exserta and Muricea pendula.

Many of the coral colonies brought back out to sea had spawned multiple times in the lab. This was a first for those species and led to the growth of brand new colonies. Having these corals in restoration labs has allowed us to learn more about their reproduction and life cycle. This information informs our efforts to restore injured seafloor communities.

Shannon Ainsworth, one of the coral aquarists, transported the precious cargo from the lab. Sasha Francis, her co-pilot, monitored the cooler temperatures along the way. After arriving at the dock of R/V Pelican , they loaded the corals on board for the offshore journey. Overnight, the ship made its way 100 miles off the coast of Louisiana, to just outside Flower Garden Banks National Marine Sanctuary .

Preparing a "Coral Elevator"

Each morning, the ship crew deployed a conductivity, depth, and temperature rosette that gathers water samples and water quality information. Unused water went in the coolers to safely store the corals before their trip back to the seafloor.

When the R/V Pelican arrived at the first outplanting location, the air was abuzz with excitement. In fact, some of the mission team had been part of the original collections of these very same coral fragments a few years before. They were now helping them return home. The Marine Applied Research and Exploration crew launched the remotely operated vehicle Beagle to make its way down to about 280 feet.

Their ride to the seafloor was on the " coral elevator, " designed by the Coral Propagation Technique Development team. "The process of figuring out what these mesophotic corals need to grow, reproduce, and thrive in the wild and in our labs so we can restore their populations has been years in the making. The work our aquarists do every day in the lab combined with the time our restoration teams spend at sea each year informs what we do next, and we are constantly adapting based on what we learn along the way. Sometimes we need very creative solutions to do things that have never been done before, like designing a unique platform to carefully put corals back on the seafloor hundreds of feet below the surface" explained Chris Gardner, one of the team's project managers and field party chief for the mission. The corals were gently affixed to a base made of a limestone and cement mixture, which provides a textured, sturdy area for the colony to continue growing. They tied a biodegradable sisal rope to move the base, and lowered the elevator down onto the seafloor.

Restoration Lab Corals Return to the Seafloor (1:49)

The Corals Have Landed

With the coral elevator now safely in the water, everyone rushed back to the monitoring screens to wait for it to appear on the seafloor. The Beagle hovered and the pilot moved it around slowly to locate the elevator. The room fell silent in anticipation. When the Beagle team spotted the elevator, they detached it from the crane cable and approached the first bucket. The ROV pilot and engineer operating the manipulator arm grasped the first rope and lifted the coral base out of the bucket. The Beagle glided over the seafloor to find the outplanting location. The site was near larger colonies of the same species in the area where the corals were originally collected. After they placed it on the seafloor, everyone cheered. But there was still more work to be done. The Beagle team repeated this maneuver seven more times-each with the same care and precision. The following day, the team completed two more outplantings to get all 24 corals back home to the seafloor. The scientists logged the corals' locations so they can continue to visit and monitor restoration progress.

Ainsworth breathed a sigh of relief that one of the most delicate parts of her job on this mission was complete. She then immediately prepared for the collection of new fragments of a wider variety of coral species. She and Francis brought them back to the labs for the aquarists to continue learning more to support the restoration of these habitats. "To be the first mission team to do this-and also have it go so smoothly-is extremely rewarding, and is a testament to the work these projects have done and continue to do," Ainsworth said. "So many of those involved were present all the way from the planning process through outplanting. Seeing this team and the animals I have cared for become a success story definitely makes me excited for what this project is going to achieve in the future."

This groundbreaking work in labs run by NOAA, U.S. Geological Survey, and partners is part of the Coral Propagation Technique Development project, one of the four Mesophotic and Deep Benthic Communities restoration projects. This mission, conducted under permit FGBNMS-2024-007-A2, included experts from:

• NOAA
• U.S. Geological Survey
• National Marine Sanctuary Foundation
• University of Rhode Island
• University at Buffalo
• Louisiana Universities Marine Consortium
• Marine Applied Research and Exploration
• Smithsonian National Museum of Natural History