Dive 10: “Wetmore” Seamount East
July 24, 2017
Access Dive Summary and ROV Data

The substrate was composed of large manganese-encrusted boulders and blocks that later gave way to cemented lava boulders and basalt; there was a light sediment overlay. Initially, a strong current came from the southeast; later, it came from the north. While the quantity of animals fluctuated in places along the crest of the ridge, the community could be described as high-density. Octocorals were the dominant fauna and included isidids, primnoids, chrysogorgiids, coralliids, Paragorgia, several species of mushroom corals, and a few sea pens. Several species of black corals observed included an undescribed species living in association with a glass sponge, zoanthids, and small anemones. Hexactinellid glass sponges were abundant, particularly Poliopogon, Caulophacus, Bolosoma, and Aspidoscopulia species. There were many associate echinoderms, such as brittle stars and crinoids. Few sea cucumbers were present, possibly due to the lack of sediment. Also observed were large purple echinothuriid urchins, an unusually small cidaroid urchin, and sea stars that included the coral predator Hippasteria. Other taxa surveyed included large patches of dead barnacles, a stone crab, squat lobsters, swimming shrimp, and small lyrate-shaped invertebrates that may have been cladorhizid demosponges. Relatively few fish were seen – only a cutthroat eel and two grenadiers. At the end of the dive, a finned octopod was briefly caught on video.