Scientists Map Largest Deep-Sea Coral Reef Off Atlantic Coast

Dense fields of Lophelia pertusa, a common reef-building coral, found on the Blake Plateau knolls. The white coloring is healthy as deep-sea corals don’t rely on symbiotic algae, so they can’t bleach. NOAA Ocean Exploration, Windows to the Deep 2019

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For the first time, scientists have succeeded in mapping the largest deep-sea coral reef in the world, which runs hundreds of miles off the Atlantic coast of the United States.

The massive 6.4-million-acre reef is bigger than the state of Vermont, a press release from the National Oceanic and Atmospheric Administration (NOAA) said.

“It’s eye-opening — it’s breathtaking in scale,” said Stuart Sandin, a Scripps Institution marine biologist, who was not part of the study, as reported by The Associated Press.

Since the 1960s, scientists have been aware of some corals off the Atlantic Coast, but the size of the reef was unknown. That is until mapping technology came along that allowed 3D images to be made of the seafloor.

“This strategic multiyear and multi-agency effort to systematically map and characterize the stunning coral ecosystem right on the doorstep of the U.S. East Coast is a perfect example of what we can accomplish when we pool resources and focus on exploring the approximately 50% of U.S. marine waters that are still unmapped,” said Derek Sowers, the study’s lead author and Ocean Exploration Trust’s mapping operations manager, in the press release. “Approximately 75% of the global ocean is still unmapped in any kind of detail.”

The reef stretches about 310 miles and is 68 miles wide in some places.

The cold-water reef was deemed the largest coral reef habitat in the deep sea discovered to date in the recent study, “Mapping and Geomorphic Characterization of the Vast Cold-Water Coral Mounds of the Blake Plateau,” published in the journal Geomatics.

For the study, researchers put together data from 31 sonar mapping surveys to make an almost complete map of the Blake Plateau seafloor, which is located roughly 100 miles from the southeastern coast of the United States.

The study area runs from the vicinity of Miami to Charleston. The standardized system used by the researchers identified 83,908 separate coral mound peaks.

Scientists nicknamed the largest area of the reef “Million Mounds.” It is made up mostly of stony coral most often found at depths of 656 to 3,280 feet, where waters are an average of 39 degrees Fahrenheit.

“Cold-water corals such as these grow in the deep ocean where there is no sunlight and survive by filter-feeding biological particles. While they are known to be important ecosystem engineers, creating structures that provide shelter, food, and nursery habitat to other invertebrates and fish, these corals remain poorly understood,” the NOAA press release said.

Derek Sowers, an oceanographer with nonprofit Ocean Exploration Trust, said only about three-quarters of the ocean floor has been high-resolution mapped, so there is a chance even bigger deep-sea reefs are still out there.

“For years we thought much of the Blake Plateau was sparsely inhabited, soft sediment, but after more than 10 years of systematic mapping and exploration, we have revealed one of the largest deep-sea coral reef habitats found to date anywhere in the world,” said Kasey Cantwell, NOAA Ocean Exploration chief of operations, in the press release. “Past studies have highlighted some coral in the region, particularly closer to the coast and in shallower waters, but until we had a complete map of the region, we didn’t know how extensive this habitat was, nor how many of these coral mounds were connected.”

^{Prior to Windows to the Deep 2018, this section of the Blake Escarpment appeared to be an area of low slope with no distinct features. Images captured during the expedition show sponges, corals, urchins and other organisms populating outcrops of hard substrate on the seafloor. NOAA Office of Ocean Exploration and Research, Windows to the Deep 2018}

Both deep-sea coral reefs and tropical reefs are at risk from oil and gas extraction and climate change, said co-author of the study Erik Cordes, who is a marine biologist with Temple University, as The Associated Press reported.

“Studies such as this one provide a better understanding of how populations of corals and other deep-sea species may be related across geographically separated locales (a concept known as connectivity) which in turn can offer insight into the resiliency of these populations. This is important for predicting the impacts of human activities on coral communities and for developing solid plans for their protection,” the press release said.

^{The mapping team celebrating World Hydrography Day on board NOAA Ship Okeanos Explorer during the Windows to the Deep 2019 expedition. NOAA Office of Ocean Exploration and Research}

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