The third Regional Cabled Array Operations and Maintenance cruise took place July 25 to August 29 onboard the R/V Revelle (RR1713-RR1715) utilizing the remotely operated vehicle Jason. As part of the UW commitment to provide students with sea-going opportunities, 23 undergraduate and graduate students participated on the expedition from the University of Washington, Western Washington University, and Queens College.
One interesting component of this cruise was the occurrence of millions of pyrosomes offshore, likely due to the presence of warmer waters in the NE Pacific than normal. During Leg three on August 21, a total eclipse of the occurred while the Revelle was at sea. Live data streaming from cabled zooplankton instruments were used to document the change in behavior of zooplankton during this event in response to rapid darkness. The zooplankton missions were modified for higher sampling intervals and showed a dramatic migration of zooplankton to shallower waters as the full eclipse was underway, followed by a return to deeper waters as the eclipse waned.
During the cruise 45 Jason dives were completed that included:
- Turning of three junction boxes (LJ01A-Slope Base; LJ03A – Axial Base; and LV01C-Oregon Offshore);
- Three Shallow Profiler Platform Assemblies and three Shallow Profiler Science Pods
- Two Benthic Experiment Platforms at the Oregon Offshore and Shelf sites
- 116 core OOI instruments were turned-installed
- One Deep Profiler mooring was installed at the base of Axial Seamount, one turned at the Endurance Offshore Site and one unplugged (Slope Base).
Installation of new PI instruments onto the Regional Cabled Array was also an important component of RR1713-RR1715. This work included the installation of a bottom pressure-tilt instrument and a CTD in the ASHES hydrothermal field. The bottom-pressure tilt was transferred to a OOI Core instrument in 2019.
In addition to the main expedition, other maintenance activities that took place on the Regional Cabled Array included a short cruise to complete installation of a digital still camera, zooplankton platform and benthic experiment platform at Oregon Shelf Site. Visibility during multiple visits to the site during RR1717 was too poor to turn the instruments, so a brief add-on cruise (RR1717 ) was conducted September 9-11, 2017.