Mushroom Hunting

‘Chimlets” atop the hydrothermal edifice called Inferno vent 300°C fluids into the near-freezing surrounding ocean water. Credit: UW/NSF-OOI/WHOI, V19.

Excitement mounted as Jason descended slowly through blue Pacific waters. As the vehicle approached 1500 meters depth, more and more people crowded into the control room to witness arrival at the ASHES hydrothermal vent field atop Axial Seamount.

As soon as the seafloor was in sight, we could see threads of white bacteria flowing along cracks in the black basalt, remnants of a past volcanic eruption at this location. This is an active volcanic caldera, where cold bottom water is pulled into channels in the seafloor, is super-heated by the pockets of 1200°C magma below, and flows out of the cracks loaded with dissolved metals and volcanic gases.

Tube worms at Inferno

As the heated water hits the colder ocean water, the minerals precipitate out (iron sulfides, sulfate-bearing minerals, and silica) forming tall spires and chimneys that are oases of life. Here, the gas-rich fluids support support tubeworms and other chemosynthetic organisms (and the animals that graze on them). The worms have an organ called a trophosome containing bacteria that thrive on the gases and oxygen in the water. The worms absorb the sulfur-rich gases (e.g. hydrogen sulfide- think rotten eggs) and oxygen via their bright red gills, and the bacteria in turn provide energy to the host worms (who have lost their digestive systems, so cannot feed themselves).

Jason arrived at the site with a new HD video camera to replace the one deployed in 2018, and the first step was to survey the site and confirm that the plan to unplug, move, and replace the camera would work as designed. The HD camera is positioned directly in front of a vent named Mushroom (~12-13 ft tall), which is directly across from another chimney called Inferno, and surrounded by other equipment and sensors.

The newly installed HD camera, built by the UW Applied Physics Lab, lights up the hydrothermal chimney ‘Mushroom’. Credit: UW/NSF-OOI/WHOI;V19.

The obstacle course makes flying the ROV while carrying a heavy camera tripod a potentially tricky maneuver. Once the old camera had been unplugged and moved out of the way, the new camera was carefully positioned in an almost identical location – another difficult task, due to the uneven slope and bumpy lava flow covering the seafloor. Finally, after a few twists and turns to orient it, the new camera was in the correct position, plugged in, and the moment of truth arrived: engineers on shore at the University of Washington, >300 miles away from this active submarine volcano, turned on the power and watched to see if the video stream, lights, and pan/tilt unit would operate correctly. All folks both onshore, in the Jason control room, and in the ships’ main lab, gave a big sigh as the camera lights lit up the darkness.

In a testament to the design and pre-deployment testing of the camera, everything operated perfectly, and we were able to watch the live video appear on the Ocean Observatories Initiative website and also on the ship. This is a technologically amazing feat – the HD camera live video, starting at the summit of the volcano and nearly a mile beneath the oceans’ surface, streams at the speed of light to the UW through more than 500 km of fiber optic cables on the seafloor, comes ashore in Pacific City, Oregon, and from there goes to the UW. From there it is sent over the Internet to a satellite thousands of miles above Earth and back to the ship far offshore in the NE Pacific ocean….

The remainder of the dive was dedicated to putting the old camera onto the undervator for recovery and collecting a few other instruments (temperature probes and an osmosampler that slowly collects fluid from the seafloor using a salt pump) for transport back to the surface. It has been an exciting day at Axial, both from an engineering standpoint (hooray for working equipment!) and from a science standpoint (bizarre animals, filamentous bacteria waving in shimmering 300° fluid, and unique geological formations). We’ll be spending another day here recovering and redeploying equipment, so we’re looking forward to even more interesting video and scientific discussions!