One of many sightings during today’s dive of a seastar feeding on coral. Here you can see a Calliaster sp. seastar tube feet feeding on bamboo coral.

One of many sightings during today’s dive of a seastar feeding on coral. Here you can see a Calliaster sp. sea star's tube feet feeding on bamboo coral. Image courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts. Download larger version (jpg, 844 KB).

While at “Tropic of Cancer” Seamount, we observed a diversity of coral and sponge species. Shown here is a glass sponge and a diversity of octocorals.

While at “Tropic of Cancer” Seamount, we observed a diversity of coral and sponge species. Shown here is a glass sponge and a diversity of octocorals. Image courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts. Download larger version (jpg, 2.0 MB).

Dive 01: “Tropic of Cancer” Seamount
September 7, 2017
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Prelude

During the first dive of the Deep-Sea Symphony expedition, we explored a dense community of deep-sea corals and sponges on a site dubbed "Tropic of Cancer" seamount, at a depth of ~1,900 meters (6,230 feet). Along with a diversity of octocorals, hexacorals, and glass sponges, scientists encountered some particularly large colonies of bamboo corals and chrysogorgid corals. The dive site was selected based on a model by the NOAA National Centers for Coastal Ocean Science (NCCOS), which predicted that this seamount would be host to a diversity of coral species. Video courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts. Download (mp4, 23.1 MB)

Today’s dive took place at the “Tropic of Cancer” seamount, located about 90 nautical miles north of Oahu, Hawaii. The dive scaled the slope and crest of a ridge at the summit of the seamount. The seamount is isolated from surrounding seamounts and while there was some pre-existing mapping data, it had never been explored with a remotely operated vehicle (ROV). The primary objective of today’s dive was to ground truth a deep-sea coral habitat suitability predictive model by NOAA’s National Centers for Coastal Ocean Science, which had indicated this seamount may provide suitable habitat for dense and diverse deep-sea coral communities. As ROV Deep Discoverer reached the seafloor at 1,855 meters (6,085 feet), a diversity of corals immediately came into view. We encountered several different species of coral including bamboo corals, bubblegum corals, black corals, and mushroom corals. Several species were present in high density and many were very large, indicating an old colony. Other animals observed during the dive included a holothurian, a cutthroat eel, sea pens, a chanux (goosefish), shrimp, sponges, and a number of sea stars predating upon bamboo corals.