EX1803: April 11-May 3, 2018  Science Leads: Adam Skarke and Daniel Wagner

1. Explore and discover vulnerable marine habitats – particularly high-density deep-sea coral and sponge communities
2. Explore areas relevant to resource managers such as Essential Fish Habitats, Habitat Areas of Particular Concern, and national marine sanctuaries and their proposed expansion areas
3. Explore the diversity and distribution of benthic habitats – including bottom fish habitats, chemosynthetic, and deep-sea coral communities
4. Investigate the geology of the Gulf of Mexico
5. Explore U.S. maritime heritage by investigating sonar anomalies and characterizing shipwrecks
6. Acquire a foundation of ROV, sonar, and oceanographic data to better understand the characteristics of the water column and the fauna that live there
7. Collect high-resolution bathymetry in areas with no (or low quality) sonar data
8. Engage a broad spectrum of the scientific community and public in telepresence-based exploration and provide a foundation of publicly accessible data and information products to spur further exploration, research, and management activities

The 23-day expedition focused on acquiring data on priority exploration areas identified by ocean management and scientific communities and helped to establish baseline information in the region to catalyze further exploration, research, and management activities.

Conducted 15 ROV dives ranging in depth from 305 to 3,010 meters (1,001 to 9,875 feet) to explore the diversity and distribution of deep-sea habitats and associated marine communities in the Gulf of Mexico basin. Operations focused on characterizing deep-sea coral and sponge communities, bottomfish habitats, submarine canyons, shipwrecks, and chemosynthetic habitats such as brine pools, gas seeps, and mud volcanoes. Midwater exploration at depths ranging from 900 to 300 meters (2,952 to 984 feet) was also conducted during two dives to investigate the diversity and abundance of the largely unknown pelagic fauna. Highlights from the dives include:

• Observed hundreds of different species of animals, including several potential new species, new behaviors, and numerous significant range extensions. Some noteworthy observations included:
• Unusual behavior of a potentially new species of squid seen at about 850 meters (2,789 feet) during Dive 04 of the expedition.
• Coral and sponge communities documented during 12 of the ROV dives (Dives 03 - 15), including five high-density communities of deep-sea corals, one of which is currently among the deepest high-density communities (2,600 meters) known from the Gulf of Mexico.
• First-time documentation of several species of sea stars feeding, including one feeding on a black coral.
• First-ever scientific surveys with submersibles in unexplored areas of Perdido Canyon.
• Possible first-ever in situ observation of the rare sea star, Remaster palmatus (family Korethrasteridae).
• Collected 67 biological samples (22 primary and 45 associated and commensal taxa). Thirteen of the biological samples represent substantial range extensions, and several of these may be new species to science.
• Surveyed two sites near priority areas identified by the Gulf of Mexico Fishery Management Council for potential future establishment of Habitat Areas of Particular Concern (HAPC). Information collected during those dives will provide critical baseline information to inform science and management decisions.
• Explored two proposed expansion areas for Flower Garden Banks National Marine Sanctuary to collect critical baseline information to inform science and management needs.
• Explored two archeological sites to support Bureau of Ocean Energy Management (BOEM) and NOAA maritime heritage programs, resulting in 3D models of both sites.
• During Dive 01, archaeologists and scientists explored the shipwreck of the tug boat New Hope for the first time. Information collected during the dive confirmed the identity of the wreck and might help support an application of the New Hope shipwreck to the National Register of Historic Places.
• During Dive 02, archaeologists and scientists performed a reconnaissance survey of an unidentified wooden vessel with a limited number of metal items inside that may be related to propulsion or steering (e.g., prop shaft or rudder post).

Mapped more than 21,100 square kilometers of seafloor in the Gulf of Mexico U.S. Exclusive Economic Zone (EEZ).