These Innovative Landers Will Examine Coral Reefs in the Gulf of Mexico

Scientists plan to use what they learn to help restore communities harmed by the Deepwater Horizon oil spill

Benthic Lander
One of the new benthic landers is lowered into the Gulf of Mexico via a system of winches and safety lines. Once released, the autonomous platform sinks at a carefully calculated rate until it lands on the seafloor. Kristopher Benson / NOAA

Aboard the deck of the Nancy Foster, more than a dozen safety-gear-clad scientists and crew gather. The National Oceanic and Atmospheric Administration (NOAA) research vessel is in the Gulf of Mexico to aid a test launch of benthic landers—deep-sea autonomous research platforms. Using colossal winches and cables, the team maneuvers a pair of 2,500-pound triangular aluminum cage-like structures, studded with what appear to be orange hard hats, into the water. The University of Rhode Island built landers are outfitted with a suite of software, cameras and specimen-collection apparatus that will enable them to remain deployed almost three miles below the surface on a unique one-year mission.

For this first-of-its-kind project, under the lead of Andrew Davies, a University of Rhode Island marine biologist and the designer of the platforms, the landers will study the deep-sea corals in areas of the gulf affected by the 2010 Deepwater Horizon oil spill. After their stint on the ocean floor, they will be brought back to the surface, and scientists will analyze the gathered data to understand how the corals are recovering and interacting with their environment. The study is part of the Mesophotic and Deep Benthic Communities project, funded by NOAA and run in collaboration the Department of the Interior, which is using settlement funds from legal action following the spill. Scientists hope the information will create a first-ever baseline for deep-sea habitats, which could ultimately lead to the ability to successfully transplant corals into the areas damaged by the spill.

“We focus a lot on space exploration, but we know so little about what’s going on in the deep ocean,” says Davies. “It’s so important for us in terms of climate regulation, ocean processes, ecosystem protection and food security.”

The Deepwater Horizon accident was the largest marine oil spill in history. On the heels of eight catastrophic safety-system failures, the drilling platform, owned and operated by BP, exploded. Eleven men were killed. The rig sank, setting off an uncontrolled leak that was not capped until three months later. By then, 134 million gallons of oil had gushed into the gulf. Millions of animals were harmed or killed, including 82,000 birds, 6,000 sea turtles, 25,000 marine mammals, and a “vast but unknown” number of fish.

Within 16 miles of the leaking wellhead, at least 81 coral colonies were sickened and injured. These included several types of corals, such as octocorals and the sea fans Swiftia exserta, Muricea pendula, Paramuricea biscaya and Antipathes atlantica, which provide crucial habitat for small fish, crustaceans and other invertebrates. Nearly 15 years later, the corals’ recovery has been limited.

“Deep-sea corals are very slow to grow,” says Sandra Brooke, a coral reef expert at the Florida State University Coastal and Marine Lab. “If you’ve wiped out an entire grove of five- to six-hundred-year-old corals, you don’t expect them to come back anytime soon.”

Researchers and Benthic Lander
Andrew Davies (right) and marine biology PhD candidate Jane Carrick (left) load a piece of equipment into the lander’s sediment trap, which will collect samples every 30 days. Jess Kaelblein, Inner Space Center, University of Rhode Island

Although Brooke characterizes the corals as “thriving” prior to the spill, they were not without threat. Unlike corals in shallow water—such as those that have recently made the news because of mass bleaching—deep-sea corals are not similarly affected by warming temperatures, says Andrea Quattrini, a research zoologist and curator of corals at the Smithsonian’s National Museum of Natural History, and a collaborator on the landers project. “That’s not to say that deep-water corals are not impacted by climate change,” she says. “Ocean acidification is happening, and that can cause coral skeletons to dissolve.”

Still, Quattrini says, the biggest threats to coral come from human activity, specifically resource extraction and industrial fishing trawlers, whose weighted nets scrape the seafloor to collect fish—and wind up gathering everything in their path.

Depositing the fleet of six benthic landers into the gulf has been an expensive and thorny process. The landers cost $300,000 apiece to build and equip. Research vessels like the Nancy Foster can cost hundreds of thousands of dollars per day to operate—a main reason why shallow-water exploration is more common. Winds on the open sea are often brutal, scuttling work for days at a time. Once in the sea, the landers themselves are exposed to enormous risk.

“The ocean wants to blow out anything we toss it in,” Davies says. “It wants to collapse glass spheres, slowly dissolve an entire metal structure, eject fishing gear or debris from a storm. It’s an incredibly hostile environment”—as evidenced by the tragic implosion of the tourist submersible Titan last year, while on a dive to observe the wreckage of the Titanic.

Deep Sea Corals
Four different species of corals, including bubblegum and bamboo corals NOAA Ocean Exploration

Using knowledge gathered over the last two decades, Davies designed the platforms with ocean-safe materials that can withstand external pressure, flooding, corrosion and the force of currents. According to Brooke, landers used in previous, unrelated projects sometimes suffered from early instrumentation failure or were unable to withstand the depths. Others had faulty acoustic releases, which caused them to prematurely float to the surface and wander. And longevity is an issue. “You can put cameras on a lander, but anything that has its own internal battery is going to run out of juice at some point,” Brooke says.

Davies believes he’s corrected these problems. Each lander stands nearly eight feet tall and has been equipped with 750 pounds of weights that allow it to sink to—and stay in place on—the seafloor. After a year, when the time comes for the landers to return, an acoustic release controlled by a series of pings from the onboard team will tell the devices to drop some of their weight so they can float back up. Newer tracking technology on the platforms will allow the researchers to pinpoint each lander to within ten feet of where it breaks the surface.

Like an underwater observatory, the landers are equipped with a variety of tools that collect samples and run experiments. For example, sediment in traps will give insight into how organic matter from the surface of the ocean settles into the depths. And plates outfitted with substrates will test whether corals will naturally grow on them.

The landers also have temperature and salinity sensors, and current meters to assess the movement of the water, particles and the corals’ food sources. If everything goes according to plan, the landers will give scientists insight into the breeding dynamics of corals—and the most comprehensive view to date of life in the depths of the Gulf of Mexico.

For eight days in April, Davies’ team conducted a successful test run of two landers. “We placed our lander within five meters of a point that we picked on the seafloor,” Davies says. “We’ve never been able to do that before.”

The devices were visited in their underwater home by Pelagic Research Services’ Odysseus 6K, the remotely operated vehicle that recovered the Titan wreckage. The vehicle captured video of the landers in action and, via robotic arms, helped move an improperly attached glass float back into place atop the platforms.

After the landers returned to the surface for re-inspection and sensor programming, they were sent back down to begin their yearlong survey of the ocean floor. The other four landers—which Davies plans to equip with hydrophones, or underwater microphones—will be deployed later this year.

The scientists on the project believe the data from the landers holds the potential to heal a wounded ecosystem. Once baseline information has been established on the conditions of deep-sea communities, subsequent projects can use the evidence to develop coral-cultivation techniques in the lab and ultimately facilitate new growth of coral species in injured habitats across the Gulf of Mexico.

Davies says the project could be a significant step in giving nature the tools to heal itself from a catastrophe—and provide a reminder of the importance of preventing a similar disaster, even as oil drilling moves farther offshore and into deeper waters.

Get the latest Science stories in your inbox.