Dive 13: “Tunica Mound”
December 16, 2017
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Dive 13: Shortfin Squid

This shortfin squid, of the genus Illex, was seen swimming in the water column. It released quite a bit of ink, likely in response to Deep Discoverer's presence. Video courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2017. Download larger version (mp4, 21.2 MB).

Deep Discoverer (D2) touched down on the gently sloping seafloor at “Tunica Mound” at a depth of 395 meters (1,296 feet) and proceeded to climb a series of terraces in the northern section of this area before heading west along a ridge. Most of the area was sedimented and hosted a high diversity of fishes. Invertebrates observed included a variety of crabs, squat lobsters, sea stars, tube-dwelling anemones, and a sea pen with commensal shrimp. Due to the lack of hard substrate, organisms attached where they could; for example, we observed a human-made tube heavily colonized by anemones and hydroids. A number of unknown siboglinid tubeworms with red plumes and Lamellibrachia sp. tubeworms also provided hard substrate for anemones, zoanthids, hydroids and barnacles. As D2 progressed upslope, we observed small carbonate outcrops that harbored a variety of octocorals and black corals. Continuing upslope, we discovered a large craggy rock column about two meters tall of unknown origin and composition covered in brisingid sea stars and surrounded by irregular rubble on the seafloor. Stichopathes sp. antipatharian whips dominated the surrounding rubble but were accompanied by many of the same species observed at previous outcrops. Several species of fishes, including Darwin’s slimehead, conger eels, and a scorpionfish, inhabited nooks in the column. We also saw numerous amphipods on a fragment of water hyacinth and a wood fall surrounded by shrimp and ampharetid polychaete worms, and heavily bored by numerous wood-eating bivalves. Unfortunately, the dive was cut short by deteriorating weather, so we had to recover the remotely operated vehicle early.