Full steam ahead! – Leg 3 continues

An octopus species commonly found on RCA dives near Axial Seamount, Graneledone boreopacifica – spotted at eastern flank of Axial Caldera. Credit: UW/NSF-OOI/CSSF; V22.

Today marks day 7 of Visions 22 Leg 3. We are just past the halfway point of this scientific journey, and everyone is fairly settled into their roles onboard and life at sea on a working vessel. We are currently at Axial Seamount, the underwater volcano that is located at the center of both a geological hotspot and a mid-ocean ridge approximately 300 miles off the Oregon coast. The seafloor composition of basalt rock formations and active hydrothermal vents is very different from our previous sites where large swaths of flattened loose sediment were the norm.

HPIES – Horizontal Electric Field Pressure and Inverted Echo Sounder getting prepped for deployment with sunrise in the background.
Credit: M. Elend, University of Washington, V22.

ROPOS had another successful dive to turn the third and final deep profiler vehicle (DP03A) at Axial Base. We deployed an unusual looking instrument called HPIES – Horizontal Electric Field Pressure and Inverted Echo Sounder. This instrument measures bottom pressure, water column heat content, roundtrip acoustic travel time and other parameters. HPIES free falls over the side of the ship instead of being lowered by ROPOS, and it took around 43 minutes to reach bottom at 2600 m (8530 feet)! ROPOS recovered the old HPIES, successfully turned junction box LJ03 with attached CTD tripod, and installed a pressure sensor at Axial Base before moving on to Axial Caldera.

UW students on bridge tour of R/V Thomas G. Thompson, chief mate in center. Credit: M. White, University of Washington, V22.

We started to see more diverse marine life and structures as we approached the caldera. Our first site, called ASHES, included active hydrothermal vents (aka chimneys or smokers), and octopuses among many more animals! ROPOS did a dive to turn the Osmo fluid sampler, an instrument assembled and prepped extensively by UW student workers that takes time-series samples of low to moderate temperature diffuse flow fluids in areas rich in vent life.. We also cleaned the HD camera at the vent called Mushroom. Video is streamed live every three hours to shore from the HD camera for all to see, imaging the entire ~ 12-14 ft tall edifice covered in life. ROPOS also conducted a full site survey of junction box MJ03B with surrounding instruments. Vertical video surveys of Mushroom and Inferno vents were conducted in order to create updated photomosaics.

Students ran all oxygen and chlorophyll samples onboard in the analytical lab under the direction of co-chief scientist Julie Nelson. They also squeezed in a tour of the ship’s engine room, and a tour of the bridge! It has been a very busy past few days with still more exciting work to come.