On the 28th, we continued work on the Shallow Profiler Mooring at the Oregon Offshore Site. It went very well and by 2200 work at that site was completed for the Leg. The R/V Revelle steamed ~ 2 hrs to the Slope Base site, which is near the base of where the Juan de Fuca Plate begins its dive under the North American Plate. Here, the water depth is 2900 m (~9500 ft). The goal of the first dive on July 29th, was to turn a junction box that was installed last year on the seafloor. This platform has an array of instruments on it that measures the salinity of the ocean and dissolved oxygen content, currents and heat content among other oceanographic parameters.
This area is strongly influenced by the California Current that brings cooler waters from the north. Strong winds push surface waters away from the coast, promoting strong upwelling of cool, nutrient waters up onto the margin – some of the most biologically productive waters in the ocean. The array of cabled seafloor infrastructure and moorings, provide 24/7 live monitoring of this dynamic environment.
Jason Dive J2-973 went well at the Slope Base site to turn the junction box. At this site, we saw numerous pyrosomes (small “pickle”-shaped gelatinous animals) in the water column that have “invaded” the northeast pacific this year by the millions. It is unclear why they have appeared in such high abundances this year, since typically they are found in warmer waters.
Of special note, is that we had our annual visitor from fish that we have fondly named “weird” fish (Genioliparis ferox). These were first filmed by the Canadian ROV ROPOS during the VISIONS’14 installation cruise. They are voracious, with large jaws: they had been previously seen in the Southern Oceans, but never filmed. We have seen a few of them every year at the Slope Base Site. At the end of the dive when Jason was coming aboard it was discovered that Jasons' tether had a serious hockle (kink) it and had to be reterminate – a 12 hour process. With this in mind, and because it was predicted that seas would build along the margin, preventing dives with packages underneath the vehicle, we decided to use the down time to transit to Axial Base to turn the instrumented platform and winched science platform on the Shallow Profiler.
The transit was amazing – at 12 knts (~14 mph), it was difficult to tell the ship was traveling through the sea. We arrived on station in the wee hours of the morning today (July 30th). Co-Chief Scientist, Orest Kawka, conducted a full water column CTD cast (2700 m; 8858 ft) to measure ocean parameters and to collect water for follow-on chemical analyses to verify the cabled instruments.
Following the CTD, a science pod was recovered in a way that we had never done before. The cable on the science pod that allows it to go up an down through the water column earlier this year had become tangled such that the science pod could not be pulled down back into the docking station; it was ~150 m above the mooring platform. So Jason went down with a new “buzz” saw on the front of the vehicle and cut the cable like butter very near to the docking station. With 400 lbs buoyancy, the science pod rose extremely rapidly to the surface where it was recovered onboard the R/V Revelle – this first time operation went flawlessly thanks to extensive planning by the Cabled Array, Jason and Revelle team. A 'hairy beast" it was covered in feathery animal communities. The students also found juvenile scallops and even a mussle on the pod during cleanig, amazing since we are >300 miles offshore and in the open ocean.
At this time, we are just finishing up the last tasks that will complete turning of the platforms at Axial Base. Then onto turning another junction box on the seafloor similar to the one at Slope Base. We are keeping a keen eye on the weather as we must return to the Cascadia Margin to complete turning of the Shallow Profiler components at Slope Base, along with other tasks…Current weather conditions would not allow us to work there.
The chefs on the R/V Revelle are treating us to a barbecue tonight – we are getting spoiled.