From July 4 - 25, 2011, Ocean Networks Canada navigated an impressive installation and maintenance expedition in the northeast Pacific Ocean. Diving down to the seafloor to investigate our 800-km cabled network observatory along the northern Juan de Fuca plate, we tended to our technically-advanced instruments and witnessed some of the amazing marine life dwelling off the coast of Vancouver Island, British Columbia.

THE JOURNEY

Aboard the R/V Thomas G. Thompson (University of Washington), we completed 33 dives at all 5 active node locations. Our route was

1. Cascadia Basin (2660 m depth)
2. Endeavour (2300 m depth)
3. Clayoquot Slope (1260 m depth)
4. Barkley Canyon (396 - 981 m depth)
5. Folger Passage (100 m depth)

Fortuitously, smooth seas and astute judgement hailed the ship around for a second pass, returning it to Barkley Canyon, Endeavour and ODP 889.

THE PEOPLE

Many thanks to the crew of the R/V Thompson for their wonderful hospitality and excellence in operating this world-class research vessel. In addition to the ship’s crew, our full complement included the 9-man ROPOS team, 2 visiting IFREMER technicians, 3 University of Washington technicians, 2 contractors, 5 university students, and 6 Ocean Networks Canada staff members. Under the guidance of Chief Scientist Lucie Pautet and Co-chief Scientist Marjolaine Matabos, we accomplished many of our objectives and improvised supplementary dive plans to enhance our time at sea and to finish some tasks slated for the upcoming September expedition.

Onshore staff also kept busy commissioning newly-installed and redeployed instruments, trouble-shooting access to live video on our website, and updating both scientists and the public on unfolding events. One great example of cooperation between ship and shore occurred during the final dive of the expedition, when we managed to restart high-quality data recording at the currently autonomous CORK U1364 at ODP 889. Quick thinking on the shore by Robert Meldrum (Geological Society of Canada), Earl Davis (GSC), John Bennest (contractor), and Martin Heesemann (Ocean Networks Canada [ONC]), with Martin Scherwath (ONC) and Reece Hasanen (ONC) testing and practicing the procedure on the ship, led to a revival procedure for this Integrated Oceanic Drilling Program (IODP) CORK. Data analysis showed that 1 sensor had a leak, compromising the entire CORK, so ROPOS cut the cable to the faulty sensor. The maneuver worked and the data logger became accessible again and could be reprogrammed. There is now data recording on 4 pressure gauges.

THE HIGHLIGHTS

In our 21 days at sea, we

1. Installed 15 instruments;
2. Redeployed 4 instrument platforms and 11 instruments;
3. Recovered 2 instrument platforms, 26 instruments, Wally the Crawler(carries an additional 7 instruments), and 9 km of electric-optic cable;
4. Repaired IODP CORK U1364A and successfully downloaded data;
5. Surveyed areas to lay down new cable during our next expedition.

On top of all this maintenance, we gathered 117 samples during 21 of the 33 dives and at nearly every visited location. When our science crew arrived at the Esquimalt Graving dock, we greeted them with a car full of coolers! The principal investigators and their research teams will analyze the samples, which included:

• Tubeworms
• 4 scoop samples
• 20 water samples
• 28 Niskin bottles
• 65 push-core sediment samples

One of the major objectives of the expedition was to investigate the power outage at Barkley Canyon that occurred on February 18, 2011. Site inspection showed instrument and cable damage at Barkley Upper Slope and Barkley Benthic Pod 2, which may have been caused by a trawl hit. All equipment was accounted for and the end of the main extension cable was recovered, sealed, and will be re-terminated. Actual repair is planned for 2012. The 2 instrument platforms and a number of instruments were brought back for further repair. At this point, we stand to lose over a year of unique and valuable data from this benthic environment. Furthermore, we were forced to delay deploying the Vertical Profiler System (VPS), which consists of a seafloor platform and a motorized tethered float that serves as a host to a collection of instruments for monitoring processes in the water column.

THE ACTION

Cascadia Basin

• Piezometer installed and data running.
• Auxiliary platform installed.
• Conductivity-Temperature-Depth sensor (CTD) swapped for re-calibration.
• 3 bottom pressure recorders (BPR) recovered.

Endeavour

• Recovered benthic and resistivity sensor (BARS).
• Final troubleshooting of last October’s loss of communications with theMain Endeavour Vent Field: the junction box was found to be operational identifying the cable as the faulty element, which will be replaced during the September 2011 expedition.
• In-situ testing of Cabled Observatory Vent Imaging Sonar (COVIS) and Remote Access Water Sampler (RAS) confirmed operational status.
• Inspected Tempo-mini site; installation delayed to September 2011 when site can be powered by a new cable. 
• Surveyed Mothra and future mooring sites.
• Recovered 5 km of a 6 km failed cable at MEF and all 4 km of the cable at Regional Circulation Mooring North (RCMN).

Clayoquot Slope

• Recovered the multibeam sonar.
• Deployed CTD.
• Retrieved data from IODP CORK U1364A, and made a repair so that it is now recording data on 4 pressure gauges.

Barkley Canyon

• Attempted to deploy temperature probes at Barkley Hydrates; however, due to subsequent technical problems, the instrument had to be recovered.
• Recovered Upper Slope Instrument Platform and Barkley Benthic Pod 2, as well as their associated instruments.
• Recovered and sealed the Upper Slope extension cable.
• Recovered, cleaned, inspected, and redeployed Pods 1, 3 and 4.
• Added the RDI Acoustic Doppler Current Profiler (ADCP) from recovered Pod 2 and redeployed at Pod 1.
• Swapped the hydrophone at Pod 1.
• 2 Nortek Aquadopps moved from Pods 1 and 3 to separate auxiliary platforms to reduce interference with other acoustic instruments.
• Recovered 2 Kongsberg rotary sonars from Pods 1 and 3 for refurbishing for future redeployment.
• Swapped 2 camera pan-tilt systems due to corrosion at both Pods 1 and 4.
• Connected a sediment trap to Pod 3.
• CTD swapped for calibration at Pod 4.
• Recovered Wally II for maintenance; however, technical problems precluded immediate redeployment. Repair is underway and the plan is to redeploy Wally II in September 2011.

Folger Passage

• Replaced BPR, ADCP and hydrophone at Folger Deep.
• Folger Deep Instrument Platform recovered, cleaned and redeployed.

THE FUTURE

Principal investigators will analyze their samples and watch the data stream in from their newly-deployed and recalibrated instruments. We will reflect on the efforts of this expedition and continue preparations for the next one, which is scheduled to embark on September 9, 2011. In the meantime, you can watch our high-definition dive videos on SeaTube (login required), look for highlights on our YouTube channel, and browse through some of the outstanding photographs we gathered on Flickr.

Thank you to everyone who made the expedition possible!