Geomorphologic Characterization of Seabed Features in the Central Region of the Blake Plateau, Southeast U.S. Continental Margin

As a follow up to the NOAA Office of Ocean Exploration and Research’s (OER) Windows to the Deep 2018 expedition, the NOAA Ship Okeanos Explorer conducted Windows to the Deep 2019, on the Southeast U.S. Continental Margin during May-July of 2019. Scientists collected multibeam sonar data containing backscatter to expand the breadth of bathymetric areas that are mapped in high-resolution on the Blake Plateau, a broad and relatively flat area that extends beyond the continental shelf and descends gradually to the Blake Escarpment, marking the edge of the continental slope. This study evaluates the geomorphology of distinct seabed features found when examining the backscatter intensity, including individual mound features that lie in two newly mapped areas, the Central Plateau Mounds and the Blake Plateau Knolls. These sites lie approximately 240 km east of the Florida coast in water depths of approximately 850 m. Unlike many of the previously mapped areas of the Blake Plateau, both sites are located to the northeast of the Gulf Stream, rather than lying directly beneath the Gulf Stream’s current. The ROV Deep Discoverer dove at selected sites within each area to collect high-definition video. At each site, individual coral mound structures were transversed, recording details of these features. High abundances of coral, sponges, and other marine organisms were observed at both sites. Similarly, both the Central Plateau Mounds and the Blake Plateau Knolls contained relatively unconsolidated substrate. The purpose of this study is to provide insight into the complex structure and potential extent of benthic communities of the central Blake Plateau by classifying benthic substrate.