A summary of Ocean Networks Canada’s maintenance expedition in the northeast Pacific: Wiring the Abyss, Leg 2, 6-26 June 2017.
Big swells rock exploration vessel (E/V) Nautilus and cable ship (C/S) Cable Innovator during a tricky seafloor operation to lay three kilometres of cable at the Cascadia subduction zone (Figure 1). Over a kilometer below the choppy ocean surface, this fibre-optic cable connects a variety of deep sea sensors, including several accelerometers that will contribute to British Columbia’s earthquake early warning system.
Meanwhile just 350 kilometres away, a magnitude 4.8 earthquake rattles the Juan de Fuca plate off the coast of Vancouver Island (Figure 2). The instruments Ocean Networks Canada (ONC) is connecting on the nearby ocean floor are designed to help us understand seismic events like this one, highlighting the poignant urgency to complete this complex ocean engineering feat.
The storm continues to brew. Choppy seas are risky for tethered, remotely controlled vehicles (ROV) so Hercules and Argus begin their 90-minute ascent to the surface, where they will be tucked safely on board E/V Nautilus until the tempest passes. As they near the roiling surface, onboard scientists notice an unusual sight for this part of the world: a floating community of pyrosomes (Figure 3), that have mysteriously migrated from tropical waters, generating more questions than answers. It’s just another extraordinary day maintaining and upgrading the world’s largest cabled ocean observatory.
Expedition 2017: Wiring the Abyss
Every year ONC sets out to sea in the northeast Pacific for a few weeks, equipped with ROVs, ocean observing instruments and platforms, and a long list of to-do’s. Working around the clock, the crack team—scientists, engineers, ROV pilots, navigators, communicators, and ship’s crew—contend with unpredictable weather and the mighty abyss to maintain and upgrade ONC’s deep sea ocean observing infrastructure. (Figure 4). Wiring the Abyss is a critical undertaking to help us #knowtheocean, and no-one even gets wet.
Despite exceptionally boisterous weather, Wiring the Abyss 2017 constellated an international cohort of partners and collaborators—working onboard and from shore—to successfully complete maintenance and upgrades on ONC’s west coast offshore and inshore sites (Figure 4). Dozens of instruments were deployed, maintained, and connected, including new cameras and seismometers designed to increase our understanding of earthquakes, slow-slip tremors and contribute to British Columbia’s earthquake early warning system.
Connecting seismometers at the Cascadia subduction zone
The first week of the expedition involved a tricky dual-ship cable repair operation at Clayoquot Slope (Figure 5), which was further complicated by unusually big seas. At its height, 40 knot winds and four meter swells forced E/V Nautilus to take refuge in the Juan de Fuca Strait overnight until the storm abated.
The wind and waves provided the backdrop to a complex and carefully choreographed multi-day operation involving two ships, two ROVs and two mud mats anchoring three kilometres of cable to the ocean floor—at a depth of 1300 metres (Figure 6). E/V Nautilus and C/S Cable Innovator worked in tandem with ROVs Hercules and Argus over several days to successfully test, repair and lay the cable which connects the CORK to the power hub node.
The repaired cable successfully connected eight instruments at Clayoquot Slope, including a Woods Hole Oceanographic Institution tiltmeter deployed 300 metres into the CORKed borehole in 2016, an earthquake early warning accelerometer, and a new tiltmeter designed by Canadian company RBR, based on a prototype developed and tested at this location by Natural Resources Canada research scientist Earl Davis.
“The success of this year’s extension cable repair operations marked another milestone in ONC’s continuing efforts to improve the reliability, maintainability and longevity of our deep ocean cabled observatory,” says Adrian Round, ONC’s Director of Observatory Operations.
Wally comes home
The international community cheered (via hashtag #WallyComeHome) when our beloved deep sea crawler Wally was heroically rescued from Barkley Canyon, depth 890 metres. After spending almost a decade alone in the cold dark depths—exploring methane gas hydrates fields and remotely controlled from an office in Bremen, Germany—it was time for our little robot to come home for R&R—refit and refurbishing—before redeployment in 2018. Modelled on a space rover, designed to study extreme environments such as the deep sea and the poles, and named after Disney’s animated space crawler Wall-e, this charismatic deep sea pioneer will spend the next year in Victoria considering its next mission.
Celebrating Canada’s sesquicentennial
To celebrate Canada’s 150th birthday since confederation, ONC introduced the #Canada150 logo into the deep sea. Stickers were placed on many of the underwater instruments, including ROV Hercules, a float in Wallyland, and a hydrophone array at ONC’s deepest site, Cascadia Basin, 2600 metres (Figure 7). Read and watch the country’s deepest #Canada150 celebrations.
International partners, World Oceans Day and more
The three-week Wiring the Abyss expedition brought together an international cohort of partners and collaborators from the UK (Global Marine Systems), Germany (Bremen University), France (Ifremer), and the United States (Bob Ballard’s Ocean Exploration Trust, Woods Hole Oceanographic Institution, and the University of Washington).
ONC celebrated World Oceans Day by taking advantage of the Ocean Exploration Trust’s state-of-the-art telepresence and ship-to-shore technology. A special Google hangout gave the public a taste of life at sea aboard E/V Nautilus, along with teams from Schmidt’s E/V Falkor and National Oceanic and Atmospheric Administration’s Okeanos.
Along with the usual water and biological sampling, a temperature probe inserted into the hydrothermal vents at Endeavour measured over 326 degrees Celsius.
A multi-beam survey of Clayoquot Canyon provided the first high resolution map of this submarine canyon (Figure 8). This detailed outline of the deep sea contours provide valuable data for Fisheries and Oceans Canada’s glider program and Natural Resources Canada’s assessment of slope stability.
During the final few days of the expedition, the E/V Nautilus and ONC crew (Figure 9) enjoyed balmier weather in the Salish Sea while maintaining and upgrading the inshore infrastructure, including new instrument platforms at Saanich Inlet and in the Strait of Georgia.
With 95% of the planned maintenance work complete, marine biologist and post-doctoral fellow Jackson Chu came aboard to complete his 14th low oxygen transect in Saanich Inlet. On the last day E/V Nautilus spent a few hours exploring the ancient glass sponge reefs off Galiano Island. Glass sponge reefs in Hecate Strait were recently designated a marine protected area.
As a grande finale treat following days of stormy weather, the crew enjoyed a spectacular sunset (Figure 10) as E/V Nautilus returned to its berth at the Institute of Ocean Sciences in North Saanich.
“ONC’s terrific teams pulled together to make the extreme challenges of working the deep sea look like a walk in the park,” says Kate Moran, ONC President and CEO.