August 17th, mobilization day was a very busy one indeed, with the completion first of getting all Leg 1 gear off the ship and some personnel and students, completing the loading, organization, and securing of all the new equipment and supplies required for Leg 2, and the arrival in the afternoon of a new group of VISIONS’22 students.
With all aboard by 1600 on August 18, and safety briefings for the new folks completed, the R/V Thompson left the NOAA dock at 1800 and headed under the Newport Yaquina Bay Bridge. It was an extremely foggy day and one could hardly see 25 ft ahead.
We arrived at our first dive site, Oregon Shelf around 1930, and ROPOS was in the water for the first dive a half hour later! This site, at 80 m water depth is in highly productive waters and is commonly very difficult to work in due to low visibility from sediment and biologically-produced material in the water column: some years, visibility is so low that the pilots can’t even see the manipulators in front of the vehicle! However, this year, the weather gods were kind to us and work progressed very well. Within the first 41 hrs of Leg 2, we have completed five dives with ROPOS, three transits, and an echosounder survey of Southern Hydrate Ridge. Not a bad start.
In addition to the above activity, instruments are getting their finishing touches before deployment, recovered instruments are being sampled and water samples have been analyzed. Students have been working on their project proposals, writing blogs, and procuring zooplankton samples.
During last night ROPOS Dive R2222 and the deployment of the low-volatage junction box LV01B at Southern Hydrate Ridge, students were treated to close up views of bacterial mats and lots of crab, fish, sea stars and other sea creatures. This area is characterized by highly active methane seeps – some years we have witnessed explosions of hydrate-encased bubbles exploding from collapsed areas in the seafloor forming plumes that rise >400 m into the water column. At shallower depths, the hydrate dissociates releasing methane into the water column, which is then utilized by methane metabolizing bacteria in the water column. The resultant increase in biological material attracts zooplankton, which attracts krill. This is a wonderful example of coupling of process that connect the seafloor and hydrosphere!