Dive 08: Wagner Seamount
September 14, 2017
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Dive 08: A Precarious Waltz

These two crabs were observed during the dive on Wagner Seamount, at a depth of ~2,500 meters (1.6 miles). Scientists were not sure if they were observing a predation event or mating behavior during this deep-sea waltz. Video courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts. Download (mp4, 30.2 MB)

Remotely operated vehicle Deep Discoverer (D2) arrived on bottom near the base of a volcanic pillow cone at a water depth of 2,428 meters (7,965 feet). The seafloor here was composed of talus of various sizes, including large boulders and some intact lava flow outcrops. Soon after, D2 transited over an extensive sheet flow, approximately one-meter-thick at 2,430 meters (7,972 feet) that persisted upslope. The dive started slow for biology observations with some low-density communities. As we transected up the slope of the cone feature, the community increased in density with Chrysogorgid corals, mushroom corals (Anthomastus sp.), and a diversity of black corals (Antipatharians) along the way. As the slope increased, a mix of sheet flow and pillow outcrops with talus were observed. Large, isolated boulders with abundant corals were seen atop mostly barren sheet flows. As D2 continued, the slope of the feature increased, but few fauna were observed. Upon reaching the summit of the cone, we were surrounded by a bamboo coral forest at 2,248 meters (7,375 feet). The high-density community was made up of large bamboo colonies all around with a diversity of octocorals, black corals, glass sponges, and more organisms interspersed between. A highlight of the dive was two crabs seen locking in what was determined to be a mating embrace. Other fauna observations included a diversity of brittle stars and rare or novel seastars and a potentially new species of sponge.