A dandelion siphonophore imaged in a submarine canyon north of French Frigate Shoals. Image courtesy of the NOAA Office of Ocean Exploration and Research, 2016 Hohonu Moana. Download larger version (jpg, 1.1 MB).
Highlights from Dive 2 of the expedition on a submarine canyon on the north side of French Frigate Shoals. Most of our previous dives in this area had been on ridges or on seamounts. Submarine canyons are known to be important habitat features by enhancing diversity. Video courtesy of the NOAA Office of Ocean Exploration and Research, 2016 Hohonu Moana. Download larger version (mp4, 26.0 MB).
During Dive 2 of the expedition, the Deep Discoverer came "face-to-face" with this deepwater shark. The dive took place on February 28 within a submarine canyon on the northern side of the largest island atoll in the Papahānaumokuākea Marine National Monument, French Frigate Shoals. Video courtesy of the NOAA Office of Ocean Exploration and Research, Deepwater Wonders of Wake.
Dive 2 of the cruise was conducted on the north side of French Frigate Shoals, in a submarine canyon. Just after the remotely operated vehicles (ROVs) went in the water, an oceanic white tip shark was seen checking out the ROV. Once the ROV reached the bottom, it found a flat area at a depth of 1,405 meters. The surface was characterized by a heavy sedimentary blanket with scattered Mn-encrusted volcanic boulders and rubble. At a depth of ~1,390 meters, the first intact lava flows were observed. These flows were laminar sheet flows with jumbled/platy or massive textures. As the ROV moved west towards the base of the canyon wall, a few more fishes were observed, including Snaptobranchid eels and Halosaurids. The density of benthic animals remained very low and included anemones, sponges, corals, sea cucumbers, and urchins. The slope changed to a vertical wall consisting of massive boulders that were covered with isolated aggregations of pink, gorgonian, and bamboo corals. As the ROV moved up the canyon wall, the benthic fauna remained low with isolated patches of corals. At the top of the wall, the slope became more gradual and the substrate consisted of volcanic rubble with heavy interspersed sediment. After the ROV reached the top of the canyon, it surveyed along the top of the wall, where scattered aggregations of corals were seen. The ROV then came up on a large pinnacle that was covered with high densities of corals and sponges. We had to end the dive a bit early because the weather was starting to build. Overnight it got so rough we could not even collect mapping data. While we are excited to get back in the water, looking at the forecast it might be a couple days before we can dive again.