Working in the Productive Offshore Waters

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The past 1.5 days has been busy again after leaving Newport. Under calm seas we transited ~ 1 hr to the Oregon Shelf site. This area is in shallow water, ~ 260 feet deep, such that it is in the photic zone. The waters off Washington and Oregon are some of the most biologically-productive areas known, impacted by upwelling of nutrient-rich water, and at this site significant currents. Some years when we dive here, it is impossible to see the ROV’s arm in front of the vehicle because there is so much material in the water, other times, it is crystal clear. One year, a fish ball came swarming directly at the vehicle – it was an amazing site.

We arrived on station in late afternoon and immediately began operations. The first Jason dive (J2-924) was to take a Benthic Experiment Package (BEP) down that includes instruments to measure the salinity and oxygen content of the ocean water, as well as currents, temperature, acidity, dissolved carbon dioxide, the adsorption of light and a broadband seismometer that documents mammal communication as well as other sounds in the ocean.

The BEP is a big beast, at a weight of 3200 lbs, it is one of the heavier instrument packages that is latched beneath Jason. It was designed by Oregon State University and houses a low-power junction box designed and built by the University of Washington that provides the power and communications to the instruments from and to shore at the speed of light – a good collaboration between engineers and scientists at the two universities. The instruments and J-Box are housed in a large protective frame.

As Jason descended to the seafloor and the BEP installed in 2015 came into view, it was clear that the frames are also protective areas for communities of fish, crabs and anemones. A few cod came up to visit the ROV as it worked on the BEP, and a few crabs had taken shelter inside the frame. Sea anemones dotted the outside yellow protecting housing. We were lucky to get good views of the package in relatively clear waters. Jason installed the new BEP and recovered the one that the ROV ROPOS had turned last year as part of the OOI Cabled Array annual cycle of maintenance operations. After this operation, two more dives recovered and installed a zooplankton instrument for imagine both large and small organisms and a digital still camera; the three dives completed operations at the Oregon Shelf site for this year.

As soon as everything on deck was secured, the R/V Sikuliaq transited ~ 4 hours to the Oregon Offshore site, were we turned another BEP in 600 m of water (1968 ft). This was also a good test of the Jason winch, which we have been having problems with. We had a technician that was brought onboard in Newport for ~24 hours to work on the winch since it is a critical piece of infrastructure for operations. He was able to fix it and all operations at the 600 m site went well. With completion of this work, we steamed back towards Newport to ‘release’ or guest back to shore.

Once the workboat was back onboard, the Sikuliaq steamed ~ 5 hrs to the methane seep site at Southern Hydrate Ridge. For the geologists onboard, this is a special place to work – here, seeps issue diffuse to jets of methane bubbles into the overlying ocean, and the hummocky seafloor is underlain by ice-methane deposits called gas hydrates. Release of methane through the sediments supports dense bacterial mats of beggiatoa and large clams with methane-utilizing symbionts in their guts. The area changes significantly from year to year and it is a wonderful place to see Earths’ dynamic nature in action, as well as the critical interfaces-linkages of geological, biological, and chemical processes that support life on this portion of the planet hidden from the sun.