Dive 13: Paganini Seamount and Midwater Transects
September 19, 2017
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Dive 13: The Largest Predator

Using the two red laser dots, which are spaced 10 centimeters (~ 4 inches) apart, scientists estimated that this cutthroat eel was 127 centimeters (4.17 feet) long. The maximum size recorded for this fish in the literature is 111 centimeters (3.64 feet), meaning that this particular cutthroat eel could be the largest short-finned cutthroat eel ever recorded. Video courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts. Download (mp4, 32.6 MB)

Another dive, another high-density deep-sea coral community! Dive 13 was conducted on a rift zone ridge along the summit of Paganini Seamount. Remotely operated vehicle Deep Discoverer (D2) arrived on bottom at 1,812 meters (5,945 feet) in a field of jagged and angular talus surrounding a massive, almost columnar outcrop. This outcrop originated either from an intrusive complex such as a sill or large dike, or extrusively as the core of a very thick lava flow, cooling slowly and developing cleavage planes. From the moment D2 reached the seafloor, a diversity of deep-sea corals and sponges were observed in significant densities. The dominant coral family observed here was the Chrysogorgiidae, but there were numerous large colonies of precious corals (Hemicorallium sp.) and Iridogorgia, huge primnoid octocorals (Paracalyptrophora sp.), massive glass sponges (Poliopogon sp.), and several other types of octocoral. The geology of today’s dive was different from what we have observed on the previous dives. We collected two rock samples, both angular basalt that will be good candidates for carbon dating post cruise. Biological samples included black coral (Antipathes sp.) growing on a glass sponge that might be new and a colony of Acanthogorgia sp. We even collected some Aeginona sp. jellyfish feeding on an Iridogorgia coral. At the conclusion of our benthic time, we conducted four water column transects at 800, 700, 500, and 300 meters. Highlights from the transects included several jellyfish, very high diversity and biomass of siphonophores, a salp with several amphipods, many Cyclothone fishes and chaetognath arrow worms, and two cephalopods at 700 meters and 510 meters depth.