By Caitlin Adams, Web Coordinator, NOAA Office of Ocean Exploration and Research
August 24, 2018
Last week, the DEEP SEARCH science team aboard R/V Atlantis conducted two dives in the Alvin submersible approximately 160 miles off the coast of Charleston, South Carolina. During the dives, the team observed extensive reefs composed of the deep-sea stony coral, Lophelia pertusa. In May and June 2018, multibeam mapping data collected by NOAA Ship Okeanos Explorer revealed mound and ridge features on the seafloor in the same region, and with the visual observations made by the DEEP SEARCH team, scientists feel it is highly probable that these features were formed by corals.
As the stony coral Lophelia grows and dies over time (likely over thousands or even hundreds of thousands of years), new Lophelia grows atop the old skeletons, together forming 80 to 100-meter high mound structures that may stretch farther than we imagined off the U.S. East Coast. When the lengths of all the mound and ridge features mapped in the region are combined, the DEEP SEARCH team estimates that there’s approximately 85 linear miles of discontinuous Lophelia reef here.
The DEEP SEARCH team will spend the coming months and years fully characterizing the significance of these two dives and the extent and makeup of the reefs. The coral structures create complex habitats that are homes to diverse communities of invertebrates and fishes, making the reefs hotspots of biodiversity in the deep sea. Furthermore, deep-sea coral reefs interact with fishes migrating daily from the surface and help to fuel the productivity of the ecosystem in the region. These reefs are responsible for recycling nutrients from organic matter falling from shallow depths and making this food source available in surface waters through mixing and upwelling.
Scientists weren’t expecting this find, but it opens the possibilities for where Lophelia could be forming reefs. While Lophelia reefs are known to occur off the coasts of Florida to North Carolina at depths averaging 350-600 meters, the presence of these reefs at deeper depths (greater than 700 meters) and farther offshore make these newly discovered reefs unique, potentially connecting deep-sea coral habitats from the south to the north. Connected reefs can be more resilient to environmental change, thus this extensive reef complex might help to improve the overall health of deep-sea corals off the East Coast and in the larger Atlantic ecosystem.