After a long weather delay, we finally completed our last two dives of this cruise on 23 May 2010 at Barkley Canyon.
The first dive commenced at sunrise, with ROPOS carrying a newly-devised "tool tray" to the gas hydrates outcrops in Barkley Canyon. Our dive goals (both accomplished) were to retrieve a string of temperature probes and collect a couple of scoops of clam shells from the seabed. The temperature probes, which were originally deployed to a gas hydrates outcrop in Barkley Canyon on 9 September 2009, had to be recovered to adjust measurement accuracy levels. The clam shells will be used to further research into patterns and processes of carbonate shell breakdown in different marine environments.
Our final dive of the cruise commenced in the afternoon, as we raced to deploy and connect our final instrument platform before ship time ran out. Fortunately, we were able to complete the installation, and now all Barkley Benthic Pods have been recovered, refurbished and redeployed.
On Friday, 21 May 2010, we made two dives to retrieve instruments from the seafloor at both our ODP 889 and ODP 1027 locations.
Our morning dive was something of a study in acronyms. ROPOS first placed a CTD on the ODP 889 BPR, then went to retrieve an mPFA. After returning to the IP, ROPOS proceeded to disconnect and recover the SFC along with the CTD and the mPFA.
The Remotely Operated Platform for Ocean Science (ROPOS) placed a Conductivity-Temperature-Depth (CTD) gauge on the Ocean Drilling Program (ODP) 889 bottom pressure recorder (BPR) in order to compare temperature measurements between these two instruments. As it turned out the BPR reading was 2.93°C while the CTD reading ranged between 2.8501-2.8531°C. Quite cold down there!!
Then we returned to Bubbly Gulch to retrieve a second mini-Pore-Fluid Array (mPFA), like the one we retrieved the preceding dive from Barkley Hydrates. Like its twin, this mPFA was originally deployed in 2009. Here in Bubbly Gulch, the mPFA was positioned next to some intriguing seafloor cracks, which seem to indicate a deeper gas/hydrate source pushing up from below.
After returning to the Instrument Platform (IP), we proceeded to the installed Sea Floor Compliance (SFC) apparatus, which had become quite popular with local crabs (there were at least four large crabs on or next to it!) We disconnected the SFC and recovered it along with the CTD and PFA to ship. Needless to say, ROPOS had its arms full, carrying that mouthful back to the surface!
Instruments on the seafloor at ODP 889. From left: mPFA, CTD, SFC.
After our morning dive at ODP 889, we steamed 7 hours to ODP 1027 for an evening dive to the broadband seismometer installation there. Unfortunately, our newly installed broadband seismometer auxiliary (a.k.a. "BB-Aux") platform developed an electrical fault and had to be recovered. (The other one at ODP 889, however, is problem-free.)
We dove 2.6km to the seafloor, disconnected the platform, and recovered it to ship. Local rattail fish, who oversaw our efforts, have lost a nice meeting place. But we hope to return it to them during a future maintenance cruise.
On 18 May 2010 we paid a quick visit to Wally the Crawler's gas hydrate world in Barkley Canyon. Our tasks were to deploy one experiment, retrieve another, collect some clams and give Wally some TLC.
Wally the Crawler has been busy over the past 8 months, and it was time for a little clean-up. His methane sensor had become coated with a hydrocarbon film and the glass sphere surrounding his webcam had become steadily cloudier.
Equipped with high-pressure spray nozzle and scrub brush, ROPOS operators gave Wally a clean-up and untangled his umbilical cable. Now, he's ready to continue his amazing remote-control science exploration for Laurenz Thomsen and the rest of the hydrates crawler research team. We hope he will survive until the autumn cruise, when he will be replaced by Wally II.
Cruise chief scientist Mairi Best is researching patterns and processes of carbonate shell breakdown in different marine environments - CSI of marine skeletons so to speak. To further this research and help understand how this form of carbon persists in hydrate environments, we deployed a string of mussel shells to a gas hydrates mound in Barkley Canyon.
While in the neighborhood, we helped retrieve a mini-Pore-Fluid Array (mPFA) from the hydrates field. This instrument, built by Dr. Laura Lapham, collects pore-fluids at different depths in the sediments over time. Scientists are trying to understand what natural events, such as earthquakes or water temperature changes, might cause a release of methane from the seafloor.
The mPFA collects discreet water samples, which must be retrieved and analyzed in the land-based lab. It contains pumps called OsmoSamplers, developed by Hans Jannasch at MBARI, that use osmosis to slowly collect fluids over time. That means no power is required! The pumps pull water from the seafloor into a 300m long coil of very thin tubing (0.16cm diameter). Once the samplers are retrieved, the coils are unraveled and discreet sections of the tubing cut from the coil. Since the pumping rate is known, each section corresponds to specific time period. Water from these sections will be analyzed for methane concentrations and other chemistries, in order to build time-series of methane concentrations.
In Aug 2009, mPFAs were deployed at two sites. The one we retrieved from Barkley Canyon was deployed atop a hydrate outcrop. A second one was deployed near our ODP 889 location.
On 18 May 2010, we revisted ODP 889 to install an Imagenex multibeam sonar. With it, scientists hope to study plumes of methane gas that bubble from the seafloor in a portion of the Bullseye Vent called Bubbly Gulch. This methane percolates upward from gas pockets associated with gas hydrates in the seafloor. Although the gas hydrates are a frozen solid, there are fissures through which the methane escapes.
After escaping, the bubbles show up strongly in sonar readings. The bubbles are theorized to be enclosed in a thin skin of gas hydrates where methane contacts the deep cold waters here. By the time they rise to 900m and shallower depths, the plumes largely disappear as the methane re-dissolves into the seawater.
Finding the bubble plumes was not as easy as we expected. They show up clearly in sonar - if within range. During our descent, we kept a close eye on the ROPOS sonar display, but no plumes appeared. After reaching the seafloor, we then flew to a previously identified location to look for bubbles ... but could not find any. We continued searching in other locations, looking for the telltale signs of a methane seep: calcium carbonate crusts in the vicinity, bacterial mats, and an absence of sea pens. But even after 2 hours of hunting, we found no active bubble zones. ROPOS then ascended some 60m off the seafloor, and prowled around looking for plumes in the sonar.
Eventually, we found several plumes, and slowly approached them using the sonar for guidance. At times, it was like chasing a mirage, as every time we approached, the plume signature receded in the sonar. Finally, though, ROPOS found itself in the midst of a stream of bubbles, which we tracked back to the seafloor. Methane was bubbling out prolifically from a nondescript patch of sediment - with not one of the telltale methane vent markers: no nearby calcium carbonate crusts, no bacterial mats, and a sea pen living in the midst of the bubble zone!
Although this bubble patch was beyond the reach of our 550m extension cable, we placed the multibeam sonar as close to it as possible, and connected it to the ODP 889 Instrument Platform after laying the cable with Mini-ROCLS. It's hoped that in this location, the sonar will be able to detect not only this plume, but also future Bubbly Gulch plumes emerging at different times and nearby locations.
In addition to methane gas seeps, we encountered a number of interesting things in Bubbly Gulch. Small cave-like structures were frequently spotted - we don't know if these are inactive vents or if benthic fauna create them. But, we do know they appear to be popular hangouts for small rockfish living there. Other benthic fauna we observed include sea pens, brittle stars, starfish and corals.
We also found a couple of interesting man-made objects. One was an exterior housing of a sonobuoy. The inert metal housing falls away from the rest of the sonobuoy on impact with the water and sinks to the bottom.
We also happened upon an abandoned rice cooker or crock-pot and screwdriver upon which sat a large crab. ROPOS pilot Reuben Mills suggested we take a closer look, and carefully opened the lid. Inside, we discovered a mother octopus with her brood of eggs! Collaborating scientist Michael Riedel suggested adopting this creature as the Bubbly Gulch mascot. We're calling her "Kraki" for now, but let us know if you have another name to suggest.
Over the course of a head-spinning 2-day, 5-dive frenzy we fetched 3 instrument platforms, re-deployed 4 instrument platforms and collected samples from 4 different locations. The action was so quick, it was sometimes hard to know whether we were coming or going! Fortunately, our chief scientists Mairi Best and Brian Bornhold kept everything straight, and we were able to check off plenty of tasks on our to-do list.
The end of this flurry left us left with only one instrument platform on deck, Barkley Benthic Pod 2, which we hope to return to the seafloor shortly. Each of the others was cleaned and refurbished by NEPTUNE Canada instrument manager Reece Hasanen and contractors Kim Wallace and Jason Williams. Problematic instruments were removed, and some new instruments were added.
Instruments deemed unseaworthy (for return to the seafloor this cruise) included:
- Pod 3 plankton pump (significant corrosion causing mechanical problems)
- Pod 4 Imagenex multibeam sonar (corrosion on sonar head)
- Pod 4 Microbial sensors (electrical cable short and sensor damage)
- Upper Slope hydrophone (corrosion - but replaced with a new hydrophone)
NEPTUNE Canada contractors Kim Wallace and Jason Williams troubleshoot a pan & tilt mechanism for one of our seafloor video cameras.
Here's a summary of what was previously and is currently installed on or connected to the instrument platforms we have redeployed so far (changes highlighted):
With the help of ROPOS, we collected "push core" sediment samples at Barkley Benthic Pods 1, 3 and 4. These were processed on-ship by graduate student Katleen Robert, and will be sent to collaborating scientist Paul Snelgrove at Memorial University for further analysis.
ROPOS also helped us collect two "benthic islands" from Barkley Canyon axis. These clumps of hard clay support an unusual profusion of life, and will be studied closely by benthic ecologists.
On 15 May 2010, we made two dives in Folger Passage, once to Folger Deep and a second dive to Folger Pinnacle. Our goals were to:
- swap out the Folger Bottom Pressure Recorder (BPR)
- find and mark the end of the cable extending from the node up to Folger Pinnacle
- clean up our little mess from last year
Happily, our efforts met with success on all three counts!
The Folger BPR, which was deployed last September, has recently ceased operating properly with what we suspect may be a malfunction of the pressure sensor. To remedy this situation, we replaced it with a brand-spanking-new one. The following photo set shows the two BPRs in side-by-side comparison.
Many are eagerly awaiting the installation (sometime this year) of an exciting new platform at Folger Pinnacle. Unlike our other installations, this custom-designed platform will be deployed by scuba divers working in the shallow (~22m) waters of Folger Pinnacle. Learn more about research planned for this location.
In preparation for the Folger Pinnacle installation, we laid a cable last September, extending from the Folger Passage node up to a rocky crevice close to the future study site. In the ensuing months, however, dive crews have been unable to locate the cable end. We weren't sure if the cable had been buried by sediment, swept away by storms or perhaps eaten by sea monsters. So ROPOS went back to the scene of the crime, tracing the cable from the node up into the shallows of Folger Pinnacle. To our great relief, we easily located the cable end. And this time, we marked it with a couple of floats to help the scuba crew find it next time.
Cable connector hose and plug were secured to this grating for storage in September 2009. This is how they appeared when we found them on 15 May.
During our fall 2009 installation cruise, large swell complicated work in these shallow, rocky waters. Surging waves made it nearly impossible for ROPOS to hold position, and we worried that our newly laid extension cable might be swept away by heavy surf and strong currents. In an effort to secure the extension cable, ROPOS dove carrying a tool tray loaded with burlap sandbags. The idea was to drop the sand bags on the cable in key locations, thus holding it in position until follow-up work could be done.
But our plan was undone almost as soon as we reached the seafloor. Like a pro wrestler, heavy surge lifted ROPOS then slammed it into the rocky seafloor, tool tray still attached beneath the vehicle. The tray frame snapped, forcing ROPOS to recover, carrying only the harness section of the frame. We attempted to retrieve the rest of the tool tray on the following dive, but the surge was too strong, and it was too risky to approach it. So the clean-up task was left for another day.
That day came on 15 May 2010, when calmer waters allowed ROPOS to loop a rope around the broken tool tray and haul it back to ship.
A chimaera visits the broken ROPOS tool tray resting on the rocky seafloor at 43m, 12 September 2009.
The broken tool tray as we found it on the seafloor, 15 May 2010.
We weren't the only ones pleased with the result. Once secured to deck, the tray rapidly attracted the attention of numerous seagulls, seeking to snack on the rich variety of shellfish that had grown onto the tray over the winter.
Shortly after the NEPTUNE Canada Vertical Profiler System (VPS) was deployed last fall, a significant problem developed: we could extend the instrument float upward, but we could not retract it back down to the base platform. NGK technicians tried mightily, but were ultimately unable to find a way to retract the float. Our only recourse was to recover the VPS and bring it back to Victoria for repairs.
On 14 May 2010, NEPTUNE Canada, ROPOS and CCGS Tully crews worked together to retrieve the VPS from its seafloor location, 396m below the surface on Barkley Slope. To accomplish this, a custom kit had been prepared, which would allow ROPOS to the corral the errant float and rig the VPS for recovery by rope.
The kit included:
- 1 800m high-strength rope
- 4 floats
- 7 30lb weights with carabiner attachments
- 1 acoustic release
- 3 large barrels and 1 bucket (to hold the rope)
Our elaborate rescue plan detailed the following steps:
- Lower the rescue kit to the seafloor by ship's winch
- Dive with ROPOS to locate the kit
- Remove 30lb weights from kit and attach to VPS float until it becomes neutrally buoyant
- Use ROPOS to carefully guide the float down into its stowage basket and secure it
- Close VPS base platform lifting bales and hook lifting point to rope end
- After recovering ROPOS to ship, trigger acoustic release to spring the floats (attached to rope end) from the rescue platform
- Locate floats and send Zodiac crew to carry the rope end back to ship
- Thread rope through A-frame pulleys onto ship's winch
- Pull the VPS up from the seafloor to the ship
- Transfer the load to the ship's crane
- Swing the VPS around from the A-frame, over the aft-starboard side and onto deck
Amazingly, the plan went off mostly without hitch. Both Tully and ROPOS crews were highly effective in their various roles executing this complicated and potentially dangerous operation. The only snag (literally) was an unforeseen tangle of ropes floating above the rescue kit after one of the barrel tops became unfastened prematurely. But this problem was solved when ROPOS pilots used their robotic arms to carefully untangled the mess. After a long day of careful teamwork, the VPS arrived on deck by suppertime.
Some, however, were none too pleased with our efforts: those who lost their hangout when we so rudely plucked it from the seabed. A great number of fish and at least one miffed octopus witnessed the rescue operation. Sorry, guys! We'll try to return the VPS as soon as possible!
On 11 May 2010, deck preparations began for will will likely be our longest dive this cruise. Dive objectives are threefold:
- Install a new seismometer auxiliary platform
- Inspect the ODP 1027 instrument platform and nearby CORK
- Lay a 12.5km cable and install the ODP 1027 NE bottom pressure recorder
The seismometer auxiliary platform (left) rests on soft sediment as a 'dust ring' emerges from a spare parking position, 12 May 2010.
The second of two auxiliary platforms was installed near to the ODP 1027 broadband seismometer. Like its twin at ODP 889, this platform hosts an acoustic current meter, a differential pressure gauge and a back-up battery for the seismometer. Installation of this platform was aborted last fall, when an electrical ground fault was detected on the unit. We're hoping no such faults will visit this time!
ODP 1027 instrument platform visual inspection, 12 May 2010.
Several months ago, we stopped receiving data readings from the northwest bottom pressure recorder (BPR) at ODP 1027. We weren't sure what may have caused this outage, but after inspecting the instrument platform, we know why. There appears to have been damage to the media converter canister that joins the BPR cable to the platform connection hose. Although the causes are uncertain, the effect, for now, will be a continued live data outage for this instrument, as we lack necessary equipment to repair the media converter canister connector on-ship. On the bright side, the BPRs are equipped with batteries, and data collection is ongoing. We will retrieve the data on a future cruise, and add it to the data archive.
Both ROPOS arms work together to release rigging holding the media converter canister and cable end from ROCLS, 12 May 2010.
Once the first two tasks were complete, we commenced with a very time-consuming task, the laying of a power and fiber-optic communications cable from the instrument platform extending 12.5km to the northeast.
On-ship preparations for this cable lay began the afternoon of 11 May, when the CCGS Tully deck crew, along with ROPOS and NEPTUNE Canada crew members, began setting up an intricately choreographed deck ballet involving two cranes and a winch. ROCLS, the ROPOS Cable Laying System, was too heavy to deploy beneath ROPOS with such a long and heavy cable spooled onto it. As with the other two long BPR cables deployed last year, ROCLS had to be lowered to the seafloor by ship's winch. To do this, the Tully crew had to pick it up by crane, swing it out over the water and around the back and transfer the load to the winch cable. It was a delicate operation, requiring all able hands on deck holding the heavy piece of equipment fast with tag lines and trying to prevent the possibilities of damage or injury. Rough seas on the 11th prevented the operation, but it went off without a hitch on the 12th, when seas had calmed considerably.
After lowering ROCLS to the seafloor, it was released form the winch cable using acoustic releases. Then, ROPOS dove to find ROCLS, attach the cable end to the platform and begin the marathon cable lay, which lasted over 16.5 hours.
When finished, ROPOS detached the connector and media converter canister from ROCLS, plugged in to the bottom pressure recorder, and recovered to ship. We've got our fingers crossed that the BPR will be happy in its new environment and provide years of reliable data.
On 10 May 2010, we retrieved two instrument platforms from Barkley Canyon, benthic pods 3 and 4. These were installed last fall and have been in service for 8 months.
The Good News
Both platforms arrived in fairly good condition, and most instruments will be ready to return to the deep after a quick clean-up on deck. Instruments in good shape:
- video camera
- 150 kHz acoustic Doppler current profiler (ADCP)
- multibeam sonar
- conductivity-temperature-depth (CTD) gauge
The Not-so-good News
Unfortunately, several instruments were somewhat worse for wear:
- The plankton pump had been pummeled by the harsh deepsea environment and cannot be redeployed in its current condition.
- The rotary sonar head had some corrosion, but technicians have decided to redeploy it.
- One of the two microbial sensor panels is badly damaged; it's still undecided whether it will be redeployed or not.
There were some organisms observed to be growing on the platforms, but overall, it was fairly minimal. In particular, one tiny life form (shown below) seemed to be colonizing the up-canyon sides of the platform. Please post a comment if you can identify this organism.
The first dive was aborted — twice! Shortly after ROPOS entered the water the first time, the pilots noticed pressure drop quickly within the oil-filled tubes that house its electrical wires. This pressure drop was likely caused by air bubbles trapped somewhere in the system. They brought the ROV back to the ship, quickly bled the lines as best they could and re-deployed immediately.
During the second dive, pressure dropped again, but it occurred more gradually throughout the descent. By the time we reached bottom the pressure gauge read zero. It was decided to quickly drop off the new instrument platform (which was connected beneath the vehicle) and recover.
After recovery, ROPOS crew bled the lines again and prepared for a third dive. This time, ROPOS carried an auxiliary instrument platform to be connected to the broadband seismometer. This auxiliary platform holds a back-up battery to power the seismometer in event of a power outage. Additionally, it hosts a Nortek Aquadopp current meter and a differential pressure gauge. These instruments can be used to help seismologists detect and remove current, tides and wave signatures from seismic data.
During the lengthy dive that ensued, we unplugged the old ODP 889 instrument platform, plugged in the new one and installed the new seismometer auxiliary platform.
After recovery, we were happy to learn that NEPTUNE Canada systems successfully powered up and communicated with the junction box, seismometer, current meter and CSEM apparatus. Later tonight, they will do a more extensive test of the CSEM, working virtually with University of Toronto scientist Reza Mir, who is currently attending a conference in New Zealand!
On the first day of the cruise, both the CCGS Tully and ROPOS underwent operations tests in Saanich Inlet, then we sailed to the VENUS Straight of Georgia site to help diagnose a power problem with the VENUS Delta Dynamics Laboratory. Along the way, NEPTUNE Canada technicians fine-tuned instrument riggings as we traveled the scenic waters of the Salish Sea.
Late in the evening, we set course for ODP 889, – an 18-hr transit to the western side of Vancouver Island. There we need to replace the ODP 889 instrument platform, deploy an accessory platform for the ODP 889 seismometer, recover the Seafloor Compliance Apparatus and deploy a multibeam sonar at Bullseye Vent.