A swimming sea cucumber seen near the cliff. Image courtesy of the NOAA Office of Ocean Exploration and Research, 2016 Hohonu Moana. Download larger version (jpg, 560 KB).
Community

During the fourth dive of the expedition, scientists explored a headwall scarp on the north side of Pioneer Bank, which included a steep pinnacle with a vertical relief of ~400 meters. On the flanks of the pinnacle, the density of animals increased substantially and included patches of close to 100 percent benthic cover – illustrating that the deep sea is in fact full of life. Video courtesy of the NOAA Office of Ocean Exploration and Research, 2016 Hohonu Moana. Download larger version (mp4, 78.0 MB).
Sea Cucumber

Holothurians, or sea cucumbers, like this one find their food on the seafloor, but are often seen swimming in the water column between feeding sessions. Given the transparency of this sea cucumber, it is easy to see that it has eaten recently. Video courtesy of the NOAA Office of Ocean Exploration and Research, 2016 Hohonu Moana.
Jelly

This coronate jelly was seen north of Pioneer Bank in the Papahānaumokuākea Marine National Monument on March 4, 2016. Video courtesy of the NOAA Office of Ocean Exploration and Research, 2016 Hohonu Moana.
Jelly

This jelly was seen pulsing through the water column during the fourth dive of the expedition, on March 4, 2016. Video courtesy of the NOAA Office of Ocean Exploration and Research, 2016 Hohonu Moana.

Dive 4: North Side of Pioneer Bank

March 4, 2016

Water Column Exploration

While much of the Deep Discoverer's time is spent traversing and collecting imagery of the seafloor, we do occassionally catch glimpses of animals in the water column. The water column is a vast, not-well-understood habitat — another frontier to explore. Video courtesy of the NOAA Office of Ocean Exploration and Research, Deepwater Wonders of Wake. Download larger version (mp4, 69.6 MB).

Dive 4 was located on a headwall scarp on the north side of Pioneer Bank, which included a steep pinnacle with a vertical relief of ~400 meters. The objective of the dive was to survey along the flanks and summit of the pinnacle for high-density communities of corals and sponges. The remotely operated vehicle (ROV) landed on the wall of the scarp at a depth of 1,513 meters. There was no current at the landing site and few animals were present. As the ROV moved up the wall, the density of benthic invertebrates remained low and included sponges, as well as chrysogorgid, primnoid, and bamboo corals. Several fish were observed along the wall including halosaurids, rattails, and a slickhead. At 1,503 meters, the ROV collected an unidentified glass sponge, which had a commensal crinoid on it. Further up the slope, the terrain became near vertical with large undercuts, causing the ROV to have to be pulled off the bottom to avoid entanglement of the umbilical cord. The ROV remained in midwater for approximately 30 minutes, during which time shrimp and crown jellyfish were observed. We then moved closer to the pinnacle and lowered back onto the bottom at 1,320 meteres depth. On the flanks of the pinnacle, the density of animals increased substantially and included patches of close to 100 percent benthic cover. These communities were dominated by the glass sponges and corals. The ROV left the bottom at a depth of 1,156 meters. Once the ROV was on deck we started a mapping transit to our next dive site.