Unraveling the Mysteries of Océano Profundo: New organisms, ecosystems and geohazards in deep water around Puerto Rico

From February to April 2015, NOAA Ship Okeanos Explorer, America’s Ship for Ocean Exploration, surveyed unknown deep-sea ecosystems and potential geohazards off the coast of Puerto Rico and the US Virgin Islands. Over 37,500 km² of high-resolution multibeam sonar data was collected, revealing rugged canyons along shelf breaks, intricate incised channels, and large slumps and slope failures. Twelve remotely operated vehicle (ROV) dives, surveyed seamounts, escarpments, and submarine canyons at depths of 300-6,000 m. Additional ROV exploration of the water column occurred at depths of 800-1200 m. Dives included three of the deepest dives ever conducted in the Puerto Rico Trench and the first exploration of Exocet and Whiting seamounts. Discoveries included assemblages of deep-sea corals (>50 species), and observations of several rare and new species. For example, the seastar Laetmaster spectabilis had not been documented since its original description in 1881 and a new species of benthopelagic cydippid ctenophore was observed at 3900 m in the Aricebo Amphitheater. Other expedition highlights included two rarely observed blind octopods (Cirrothauma murrayi); novel observation of a symbiotic association between predatory tunicates with polychaete associates; and approximately 75 species of demersal fishes, including a new species of wrasse and the first records of Shaefer’s anglerfish and the ateleopodid jellynose in Puerto Rican waters. ROV dives traversed elements of the complete geological succession from ~1 km deep into the Cretaceous volcanic arc basement, across the carbonate platform sequence unconformity and into the uppermost Pliocene carbonates. Highlights included spectacular slope failure headwall scarps and sub-aerial karstic weathering of the youngest carbonates. All data collected during Océano Profundo 2015 are now publicly available through the National Archives and are awaiting further analysis by the scientific community.