The deep sea holds answers to many scientific questions about the origin of life on Earth, our changing ocean, and even outer space. This year, Ocean Networks Canada’s (ONC) annual Wiring the Abyss expedition expanded infrastructure to monitor both deep sea and deep space⎯from the cosmos to the core⎯reaching new milestones for our offshore observatory in the northeast Pacific Ocean.
ONC’s annual maintenance expeditions allow for instrumentation to be added, maintained, and recovered, live streaming these deep sea operations in real time so everyone can #knowtheocean. Wiring the Abyss Leg 1, aboard Canadian Coast Guard ship John P. Tully, deployed instruments and new infrastructure using the heavy lift capability of the ROPOS remotely operated vehicle (ROV). During Leg 2, the exploration vessel (E/V) Nautilus completed the final positioning and installation of Leg 1 elements, and deployed more instruments. Over 27 days at sea, the team powered on, deployed, maintained or recovered 270 devices during 30 dives (Figure 1).
Figure 1. Canadian Coast Guard Ship (CCGS) John P. Tully (left) and E/V Nautilus (right).
Expansion of instruments: highlights
The successful completion of Wiring the Abyss 2018 included many new and exciting expansion achievements for ONC and for Canada.
- To help us understand the cosmos, a neutrino experiment was deployed at Cascadia, our deepest site, to test the transmission properties of the water. The two specialized instrument arrays will evaluate the location for potential detection of neutrinos––subatomic particles that when studied can provide insight into the origin and evolution of the universe. These instruments were developed by a team at the Technical University of Munich in Germany––the same team that developed the IceCube South Pole Observatory––who watched the deployment of their instruments live from Germany (Figure 2). The collection of detailed measurements over two years will assess the deep-sea site for future use. Read more about this exciting neutrino experiment here.
Figure 2. The neutrino test site consists of a pair of 100-metre-long test strings that mimic what happens when a neutrino passes by. The team watched live as the experiment was deployed at a depth of 2,700 metres at ONC’s Cascadia observatory.
- ONC completed the installation of the final offshore seismometers for British Columbia’s earthquake early warning system. Over the last three summers, ONC has installed a total of eight strong-motion sensors along the Cascadia subduction zone at Cascadia Basin, Clayoquot Slope, and Barkley Canyon. Two kinds of Canadian-built sensors were used—a Nanometrics Titan accelerometer (Figure 3) and an RBR tiltmeter. Using two different types of sensors provides a level of sophistication that adds redundancy and allows for improved signal comparison. The proximity of these offshore sensors to a possible megathrust earthquake could provide additional crucial seconds of warning. ONC will also be installing 26 sensors on land by March 2019, when ONC delivers the system to Emergency Management BC.
Figure 3. ROV Hercules carefully submerges an accelerometer inside the buried green caisson at Barkley Canyon, the final installation of ONC’s offshore earthquake early warning sensor system.
- Wiring the Abyss 2018 successfully doubled the instrumentation at Endeavour Hydrothermal Vent Field, Canada’s first marine protected area and the world’s most international deep-sea cabled observatory site. Instruments from Canada, United States, United Kingdom, France, and China are now connected to ONC’s data management portal, Oceans 2.0. At the Main Endeavour Field, a string of three cabled Guralp Maris ocean bottom seismometers were added to a dense network of instruments to monitor seismic activity at this spreading mid-ocean ridge (Figure 4). A hydrophone was installed close to active venting activity, and three benthic resistivity sensors were added at Mothra, Main Endeavour and Main Endeavour South to monitor hot hydrothermal fluid and chloride concentration flowing from the vents. Media Factsheet on international sensors at Endeavour hot vents
Figure 4. A string of three cabled short-period seismometers were deployed at Endeavour, in a water depth of 2,200 metres. The Guralp team—who designed and manufactured the instruments—watched live from their England office.
- Good news for the water column community. After three years, the refurbished vertical profiling system was reinstalled at Barkley Canyon upper slope and is collecting data once again.
- Other maintenance tasks included relocating instruments, cleaning camera lenses, checking on or recovering devices and experiments, and repairing instruments showing irregularities in data––such as CORK 1027C, which needed a valve position changed to ensure that the correct pressure was recorded.
Using robots to observe marine life
In addition to conducting deep sea maintenance tasks and manoeuvres, ROVs are also equipped with high-resolution cameras that make it possible to conduct video surveys to study the biodiversity and abundance of both water column (gelatinous plankton and fish) and the seafloor (fish and invertebrate) benthic communities. ONC scientists onboard assisted the ROV pilots to regulate speed, height from the seafloor, and video camera settings to capture the marine life at the highest resolution possible. ONC has gathered 11 years of ROV video and data that are essential for understanding deep-sea biodiversity in the northeast Pacific (Figure 5).
Figure 5. A curious salmon shark was spotted swimming near the surface during an ROV dive ascent from Cascadia Basin.
New cameras at Mothra, Barkley Canyon mid-east, upper slope and axis are now connected and streaming. These cameras turn on at intervals throughout the day to visually monitor experiments, instruments, and the diverse marine life. Watch for yourself on our Sights and Sounds live video page.
Sampling the deep sea
During the expedition, onboard scientists collected over 80 samples from the deep sea, including sediment, benthic megafauna, water, hydrothermal vent fluid, and methane gas hydrate bubbles. Push core samples were taken at nearly every dive conducted at Endeavour, Barkley Canyon, Clayoquot Slope and Cascadia Basin (Figure 6), to support a variety of research projects, including the documentation of the region’s little-known benthic infauna (organisms living in the sediment).
Figure 6. Onboard EV Nautilus, the expedition team processes a push core sample taken at Cascadia Basin.
As part of a new collaboration with scientists from the Natural History Museum of London, benthic megafauna samples––organisms over one centimetre that inhabit the sediment-water interface––were collected at the Endeavour vent sites. Samples of other invertebrates––such as polychaete worms, crustaceans, corals (Figure 7), sea anemones, and brittle stars––were also collected for proper taxonomical identifications in an ongoing partnership with the Royal BC Museum.
Figure 7. A rock sample with resident corals and sponges collected at Clayoquot Slope Bullseye.
Methane hydrate seeps, gas, and fluid samples were taken at Endeavour hydrothermal vent field and at Barkley Canyon using a 'gas-tight’ bottle held over the hot fluids or cold methane bubble streams (Figure 8). These samples are key for determining the biogeochemical nature of the vent fluids and measuring the rates and amount of the methane emanating from the seafloor.
Figure 8. Sampling super-heated hydrothermal vent fluid using a gas-tight bottle.
Mapping the seafloor
The expedition took advantage of E/V Nautilus state-of-the-art multibeam echo-sounding equipment by mapping the ocean floor in areas of interest (Figure 9). Two surveys––between Endeavour and Clayoquot Slope and northwest of Barkley Canyon––mapped the lower portion of the continental slope around the subduction zone deformation front. These new maps will be valuable for determining future seafloor changes caused by the next Cascadia megathrust earthquake.
Figure 9. This image from E/V Nautilus’ Seafloor Information System shows the multibeam echo-sounding survey of an area between Clayoquot Slope and Barkley Canyon. The geographic (top) and water column (bottom) mapping fills gaps in existing high-resolution bathymetry along the continental slope to increase our understanding of the area.
Preparation leads to success
“Wiring the Abyss 2018 represented one of the most complex expeditions that ONC has completed. The sheer number of new instruments, platforms, and supporting infrastructure required months of preparations, focused work from ONC teams, multiple ships and ROVs and well planned and executed installations,” comments Adrian Round, ONC’s executive director of observatory operations.
Despite the challenge of working over two kilometres beneath the waves in one of the harshest environments on Earth, ONC is proud that our collective efforts achieved over 90 percent of its Wiring the Abyss Expedition 2018 goals.
Relive our expedition excitement on our video archive SeaTube, or find out what’s happening on the ocean floor right now via Oceans 2.0, where data from all of our cabled instruments can be viewed in real time.
