A considered obligate relationship between a specific species of octocoral (cf. Metallogorgia melanotrichos) and brittle star (cf. Ophiocreas oedipus). To our knowledge, these species were previously not known to occur in the Northeast U.S. Canyons Region. Image courtesy of the NOAA Office of Ocean Exploration and Research, Northeast U.S. Canyons Expedition 2013. Download larger version (jpg, 1.2 MB).
Highlights from Dive 08 to explore the east wall of Atlantis Canyon, between 1,800 meters and 1,600 meters depth. Video courtesy of the NOAA Office of Ocean Exploration and Research, Northeast U.S. Canyons Expedition 2013. Download video (mp4, 87.1 MB).
Dive 08 was conducted in Atlantis Canyon, exploring the east wall between 1,800 meters and 1,600 meters to characterize canyon geomorphology and benthic habitats, including possible coral and sponge communities. Remotely operated vehicle Deep Discoverer (ROV D2) arrived at a soft sediment seafloor with scattered rock rubble and outcrops at 1,795 meters. Halosaur fish, white brittle stars, and cutthroat eels were prevalent in this area (yet relatively few fishes were noted during this dive), and sea pens and four species of sea urchins were noted. As D2 moved up slope to the first waypoint, we approached the base of a rock wall that appeared to be calcareous mudstone/siltstone and chalky in appearance. Attached fauna (animals) included an abundance of sponges with numerous shrimp associates. Although corals were not abundantly attached to the rocks, they were diverse. We noted at least 15 species including sea pens, cup corals, and other octocorals at a depth of ~1,750 meters. As D2 continued upslope, a large aggregation of cup corals and sponges were observed on a ledge with dead cup coral rubble below it. At 1,643 meters, we came across an octopus guarding eggs attached to the underside of a ledge. The ROV moved along the wall to waypoint 3, noting extensive fracturing along the wall and capturing imagery benthic ctenophores. D2 transited upslope to cover a broader depth range. One large vertical wall at a depth of 1,637 meters had numerous sponges and a clump of live coral. The first colonies of Acanthogorgia and Acanella were observed before D2 left bottom at 1,622 meters, ending the dive. Currents at the site were considered weak.