Seafloor maps reveal the largest deep-sea coral reef near the southeast U.S. coast, extending for hundreds of miles, equivalent in size to Vermont. This extensive reef, previously unknown, supports diverse marine life. Scientists utilized advanced underwater mapping technology to reveal the reef's massive size, a mystery since the 1960s.
A Bluestriped Grunt fish swims around a coral reef in Key West, Florida, on July 16, 2023.
World's Largest Known Deep-Sea Coral Reef
Researchers used the data from 31 multibeam sonar mapping surveys and 23 submersible dives to chart the Blake Plateau, a vast sloping shelf located about 100 miles off the U.S. coastline between North Carolina and Florida.
In the study, titled "Mapping and Geomorphic Characterization of the Vast Cold-Water Coral Mounds of the Blake Plateau" published in the journal Geomatics, the maps revealed thousands of previously unknown "mounds" of deep-sea corals, also known as cold-water corals, spanning an area of 6.4 million acres between depths of 1,640 to 3,280 feet.
The largest concentration, named "Million Mounds," extends approximately 158 miles in length and 26 miles in width, establishing it as the "largest deep-sea coral reef habitat discovered to date," according to researchers.
Although scientists have known about deep-sea corals on the Blake Plateau since the 1960s, technology and funding limitations hindered a comprehensive assessment of their abundance. Derek Sowers, the study's lead author, expressed surprise at the sheer number of coral mounds revealed, emphasizing the impressive scale of the coral habitat.
Situated beneath the Gulf Stream, a nutrient-rich current of warm water along the eastern U.S. coast, the coral reef benefits from this subsurface superhighway, likely providing ample food for the corals to thrive in significant concentrations. The discovery highlights the importance of advanced mapping technology in unveiling the mysteries of the ocean floor.
Global Potential in Discovering Deep-Sea Coral Ecosystems
Sowers noted that there is a possibility of discovering even larger deep-sea coral reefs beneath similar ocean currents globally. Deep-sea coral reefs differ significantly from tropical ones, thriving in frigid waters as cold as 39 degrees Fahrenheit (4 degrees Celsius) and exhibiting lifespans extending for thousands of years.
In contrast to their tropical counterparts, deep-sea coral reefs appear predominantly white because they lack the vibrant symbiotic algae that provide color and energy through photosynthesis. This absence of algae gives them a resemblance to tropical reefs experiencing coral bleaching, a phenomenon where stressed corals expel their symbiotic algae and undergo decline.
The deep coral reefs house diverse marine life, including sharks, swordfish, sea stars, octopuses, shrimp, and various fish. Primarily composed of Desmophyllum pertusum, Enallopsammia, and Madrepora, these reefs support essential species like hake.
Despite the abundance of deep-sea reefs covering more of the ocean floor compared to tropical reefs, the latter are better known due to their accessibility. The Great Barrier Reef, the world's largest tropical coral reef system, stretches approximately 1,430 miles (2,301 kilometers) in Australia.
Sowers suggests the potential for discovering larger deep-sea reefs in the future, given that only 75% of the world's ocean floor and 50% of U.S. offshore waters have been mapped in high resolution. Mapping is crucial for assessing the risks faced by both deep-sea and tropical reefs, including climate change and disturbances from activities such as oil and gas drilling.
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