Desmophyllum (cf.) dianthus (cup coral) is a solitary deep-sea scleractinian, or stony, coral common along the walls of Alvin Canyon.

Desmophyllum (cf.) dianthus (cup coral) is a solitary deep-sea scleractinian, or stony, coral common along the walls of Alvin Canyon. Image courtesy of the NOAA Office of Ocean Exploration and Research, Northeast U.S. Canyons Expedition 2013. Download larger version (jpg, 1.3 MB).

Dive 09
July 17, 2013
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Dive 09 was conducted on the west wall of Alvin Canyon to characterize the diversity of submarine canyon geomorphology and benthic habitats from 926 to 863 meters. Video courtesy of the NOAA Office of Ocean Exploration and Research, Northeast U.S. Canyons Expedition 2013. Download video (mp4, 50.1 MB).

Dive 09 was conducted on the west wall of Alvin Canyon to characterize the diversity of submarine canyon geomorphology and benthic habitats from 926 to 863 meters. The Deep Discoverer remotely operated vehicle (D2 ROV) arrived at a seafloor covered in soft sediment at 926 meters hosting numerous red crabs, squat lobsters, witch flounder, cutthroat eels, dogfish, and midwater organisms (e.g,. ctenophores). We appeared to be in a nepheloid layer (layer of suspended sediment in the water column) with poorer visibility compared previous dives. D2 traversed large sediment scars with boulders at the end, suggesting they had recently rolled down slope. The boulders appeared to be carbonate cemented sediment, silt/mudstone and clay rich. The ROV reached the base of a vertical wall heavily bored with anemones and polychaetes tubeworms attached, where fishes were abundant and sessile (fixed) fauna including several species of sponges, cup corals and a few bamboo corals were evident. Several “white lines” were running down the wall, and it was noted that they were associated with fissures/fractures of various depths. D2 transited up a very steep vertical wall blanketed in fine, silty sediment with mudstone blocks covered in bamboo corals and sponges. Descending to the base of feature, numerous ctenophores, salp chains, and amphipods (small crustaceans) were observed in the water column. We moved upslope along a rock wall with numerous “white lines” running down the face, with a lack of attached fauna and low diversity of corals. The ROV made its way upslope to waypoint 3, approaching a large vertical wall with numerous corals, particularly solitary hard corals, growing under ledges that appeared to be white, cemented carbonate with light sediment cover. D2 concluded the dive at a depth of 863 meters.