NOAA’s Seirios camera sled images ROV Deep Discoverer during exploration of the eastern wall of Alvin Canyon during a dive on July 18, 2013.

NOAA’s Seirios camera sled images ROV Deep Discoverer during exploration of the eastern wall of Alvin Canyon during a dive on July 18, 2013. Image courtesy of the NOAA Office of Ocean Exploration and Research, Northeast U.S. Canyons Expedition 2013. Download larger version (jpg, 1.0 MB).

Dive 10
July 18, 2013
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Highlights from the dive to investigate the geomorphology and benthic habitats on the eastern canyon wall of Alvin Canyon. Video courtesy of the NOAA Office of Ocean Exploration and Research, Northeast U.S. Canyons Expedition 2013. Download video (mp4, 34.5 MB).

Dive 10 was conducted in Alvin Canyon, investigating the geomorphology and benthic habitats on the eastern canyon wall. Squid, midwater fishes, cutthroat eels, and small shrimp were prevalent in the water column before the remotely operated vehicle (ROV) arrived on soft sedimented bottom at the base of a west-facing wall feature with a light face and horizontal layering (1,088 meters). Cup coral rubble and dark cobbles were observed at the base. The ROV began investigation of a heavily bored, carbonate rock wall with several encrusting sponges, anemones, polychaete tube worms, and corals (c.f., Solenosmilia) growing under the overhangs. As Deep Discoverer (D2) transited upslope at a depth of 1,074 meters, bamboo corals and octocorals (e.g., Acanthogorgia) were noted on an overhang. A layer of non-bored, courser grain rock was between two layers of bored sediment. There was generally a lack of large fauna (animals) colonizing this courser grain rock, and the top of the wall was reached at 1,020 meters. Bamboo corals, limid bivalves, orange encrusting sponge or zoanthid, and a solitary hydroid were noted at the top of the ledge. D2 moved down slope and across a gentle slope of soft sediment with scattered rock. Uncolonized trash, fish, and fauna commonly associated with soft sedimented seafloor were present. Moving up a vertical wall at a depth of 1,056 meters, two juxtaposed walls were noted, with numerous broken slabs at the base and a sediment chute up the middle. A higher abundance of corals, including bamboo and primnoid corals, were noted as D2 continued upslope. Numerous skates and skate egg cases were observed, including at least two with parasites. With the exception of hydroids on exposed coral skeletons, few faunal associates were observed living with corals. Other geological observations included eroded slabs of rock sitting on top of wide ledges that were also in places undercut above. The ROV left bottom from a depth of ~1,010 meters.