EX1806: June 13-July 2, 2018  Science Leads: Leslie Sautter and Cheryl Morrison

1. Acquire data on deepwater habitats in the southeast U.S. continental margin to support priority science and management needs
2. Identify, map, and explore the diversity and distribution of benthic habitats, including fish habitats, deep-sea coral and sponge communities, chemosynthetic communities, and biological communities that colonize or aggregate around shipwrecks
3. Investigate biogeographic patterns of deep-sea ecosystems and connectivity across the southeast U.S. continental margin for use in broader comparisons of deepwater habitats throughout the Atlantic Basin
4. Map, survey, and sample geologic features within the southeast U.S. continental margin to better understand the geological context of the region and improve knowledge of past and potential future geohazards
5. Explore U.S. maritime heritage by identifying and investigating sonar anomalies as well as characterizing shipwrecks
6. Collect high-resolution bathymetry in areas with no (or low-quality) sonar data
7. Acquire a foundation of ROV, sonar, and oceanographic data to better understand the characteristics of the water column and the fauna that live there
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 deepwater areas offshore Florida, Georgia, South Carolina, and North Carolina are some of the least explored areas along the U.S. East Coast. Though the East Coast is home to millions of Americans and is experiencing some of the highest population growth rates in the U.S., the southeast U.S. continental margin has some of the largest gaps in high-resolution ocean mapping data on the East Coast and limited previous observations via submersibles. Exploratory missions, such as those conducted via NOAA Ship Okeanos Explorer, are necessary to expand our knowledge of unknown and poorly known deepwater areas and to provide data for decision makers.

• Conducted 17 ROV dives ranging in depth from 325 to 3,436 meters to improve knowledge of unexplored areas within the U.S. Exclusive Economic Zone (EEZ) and in deepwater areas previously mapped for the U.S. Extended Continental Shelf Project to inform management needs for sensitive habitats, maritime heritage sites, and potential resources. Data collected can be used to increase understanding of deep-sea ecosystem connectivity across the Atlantic basin.
• Collected 175 biological (53 primary and 122 associates) and 38 geological specimens. Biological specimens were representatives of new records, potential new species, dominant fauna, or were collected to support trans-Atlantic connectivity studies. Geological samples will be used to better understand the geologic history of this region, as well as to characterize habitat substrate.
• Through both mapping and visual surveys, this expedition added substantial evidence that the numerous mounds on the Stetson Mesa offshore of Florida and Georgia appear to be the slow accumulation of Lophelia pertusa coral skeletal material over hundreds of thousands of years.
• Mapped over 7,400 square kilometers and conducted three dives in the Stetson Miami Terrace Deep Coral HAPC that revealed high-density coral communities at each site. Two of these communities were also highly diverse.
• Conducted an ROV dive in Cape Fear MPA documenting several large wreckfish (Polyprion americanus), a commercially important species managed by the SAFMC.
• Discovered a high diversity of deep-sea corals and sponges on low relief, intraslope terraces (terraced features between a depth of 1,000 to 4,000 meters) along the Blake Escarpment in areas with no previous exploration.
• Explored two potential archeological sites to support the Bureau of Ocean Energy Management (BOEM) and NOAA maritime heritage programs.
• Conducted targeted overnight mapping operations to search for other potential shipwrecks in an area suspected to contain many due to the World War II Battle of the Atlantic, as well as merchant ships lost at sea along the busy trade routes of the U.S. East Coast. Dive 13 investigated a sonar anomaly, dubbed “Big Dipper,” with very strong backscatter, roughly the size and shape of a ship known to have sunk in the area offshore North Carolina; ROV imagery revealed that this site was not a shipwreck, but instead a biologically diverse rocky habitat that was home to a significant concentration of fish and corals.
• Documented three dive sites with high biological diversity and six medium diversity sites. Six dive sites had high biological abundance/density or high biomass.
• Observed deep-sea corals and sponges on every dive except one, which was a dedicated gas seep exploration dive.
• Conducted two dives that targeted water column anomalies. Both dives identified evidence of methane seepage, with bacterial mats and fauna typically associated with chemosynthetic habitats and active bubble seepage in this region.
• Observed several potential new species, recorded significant depth and geographic range extensions for several fish and coral species, and documented the presence of commercially important species - including red crab (Chaceon quinquedens) and golden crab
• (Chaceon fenneri) - in areas not previously investigated.
• Conducted midwater exploration at depths ranging from 300 to 950 meters during three dives to investigate the diversity and abundance of this largely unknown pelagic fauna.
• Made multiple observations of a species of medusa jellyfish (Cyanea sp.) in the deep waters above Keller Canyon. This species is typically observed in shallow waters, which raises new questions about shallow and deep water connectivity in the area.
• Mapped more than 29,600 square kilometers, an area larger than the State of Maryland.
• Made new insights into this region, including the discovery of previously unknown intraslope terraced feature; newly mapped karstic features on the northern portion of the Blake Plateau; unusually flat seafloor terrain when compared to predictions made by satellite altimetry on the southern Blake Plateau; and numerous likely biogenic ridges and mounds offshore Florida, Georgia, and South Carolina. Due to their size, these features cannot be resolved from satellite data and were only revealed in detail using the ship-mounted multibeam sonar.
• Discovered numerous areas of deep-sea coral and sponge habitat, which has not only improved our understanding of this region, but has habitat modeling implications that may apply to many other places in the world.
• Conducted one ROV dive on the toe of the Currituck landslide feature, one of the largest submarine landslides on the U.S. East Coast, to better understand past submarine geohazards.
• Engaged over 140 scientists, resource managers, and students, which is a record high for Okeanos Explorer missions. Participants were from 21 U.S. states and four international countries including Russia, Portugal, Japan, and Norway.