Multibeam Mapping and Remotely Operated Vehicle Exploration of the Puerto Rico and Virgin Islands Region

During October 2013, an ocean exploration project took place off the coast of Puerto Rico and the Virgin Islands. This project, a collaborative effort between the Ocean Exploration Trust, the US Geological Survey, the University of Puerto Rico at Mayaguez, the University of Rhode Island, and NOAA, was aimed at exploring regions of the US exclusive economic zone (EEZ) south of the Puerto Rico Trench axis, and north of Mona Island, Puerto Rico, and the US and British Virgin Islands, and portions of the Anegada Passage. The research vessel E/V Nautilus and the Hercules/Argus ROV system were used to expand the multibeam sonar bathymetric data coverage of the region, collect high definition video footage of seafloor features, and to collect biological and geological samples along selected transects. Particular areas of interest for targeted ROV dives included: the region where a large M7.2 1918 earthquake produced a tsunami that struck northwestern corner of Puerto Rico; a transect up the vertical wall of the Mona Rift (4000 to 1500 m depth); transects along the Septentrional fault system; dives in areas of suspected fluid flow through faults, fissures, and offshore Karst systems associated with the tilted carbonate platform north of Puerto Rico; dives in the Anegada Passage at the entry points for surface Atlantic waters that circulate into the Caribbean; and in regions to investigate and date sedimentary features offset by fault motion and potential tsunamigenic landslides. Biological sampling of many deep-sea benthic organisms (including deep water corals) have never been attempted before in this area. These samples are being used to understand more about the diversity, population dynamics, genetics, and habitat connectivity of these communities, and to provide an age constraint for disturbed sedimentary features. Until this cruise, the location and distribution of deep coral habitats in the US Caribbean was largely unknown. The available information on benthic communities associated with deep coral ecosystems in this region was mostly limited to taxonomic listings from incidental collections by fish traps, shrimp trawls and coral entanglement devices. We present the results of the first direct observations and sampling of these ecosystems.