Blog from July, 2011

The Folger Experience

The Folger Experience

by Martin Scherwath, 19 July 2011

It almost felt like going home. Two weeks through our cruise we were heading for land, but only to take on two pilots for our work at Folger Passage at the head of Barkley Sound. Larger ships are not allowed close to shore unless they have local navigators with sufficient experience on the bridge; therefore, a Zodiac was sent to Bamfield from the R/V Thomas G. Thompson to pick up the two pilots who were waiting and ready to jump in, not even the zodiac pick-up crew set foot on land. At least we were close enough to shore for cell phone coverage, a rare treat on these open ocean voyages.

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Zodiac from R/V Thompson going to pick up pilots from Bamfield.

Our aim at Folger Passage was to conduct maintenance on the instrument platform at a site called Folger Deep. It has a staggering water depth just under 100 metres, so really, the name only makes sense when compared to our nearby site Folger Pinnacle at 30 metres depth. By the way, Folger Pinnacle is actually the only active NEPTUNE Canada site that we did not visit during this cruise. The three main research objectives at Folger Passage are to:

  • identify factors controlling biological productivity both within the water column and at the seafloor
  • evaluate the effects that marine processes have on fish and marine mammals, and
  • provide learning opportunities for students, researchers and the public, many of whom will be working and studying at the nearby Bamfield Marine Sciences Centre.

We were ready to dive as soon as the zodiac and the pilots came aboard, but dinner time had also arrived, and so it was decided to delay the dive by 15 minutes. That verdict caused the longest line in the mess-hall that we've ever had!

Following dinner, everyone was keen to get down to the ocean floor. Once ROPOS submerged into the water it only took eight minutes to reach bottom (really quick compared to the three hour descent at NEPTUNE Canada's deepest node ODP1027 at 2660 metres). Unfortunately, Folger Passage waters are murky and it was really hard to see anything. Thus, ROPOS navigation relied heavily on its accurate positioning system and sonar scans. ROPOS sonar looks like a radar screen where you can see bright reflections of the instrument platform (IP). When you can finally see the IP on the visual, it is already close enough to grab with ROPOS' arms.

Maintenance of an IP happens on deck, so the IP was disconnected from the main cable, its bottom pressure recorder, and its hydrophone (usually sitting approximately 15 metres away from the platform). Then, ROPOS attached the instruments to itself and the IP, respectively, before it hopped on top of the IP to latch on and ascend.

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Stranded crabs.

Nine minutes later ROPOS was on the surface again. What came into our view was an IP that looked like it had seen much better days, as it was all completely covered in mud, algae and animals. Once the platform was secured on deck, some kind souls onboard started collecting crabs, fish and anemones to cast them back into their natural environment.

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ROPOS swinging by with the dirty Folger Deep instrument platform.

Bold attempts with power hoses and brushes were made in order to get the IP nice and shiny again, and the improvement was considerable. Had you not seen the IP just before, though, you would think it could still do with a good bath. However, the important parts were good again, and the IP was refitted with a new CTD (Conductivity, Temperature, Depth (pressure) Sensor), ADCP (Acoustic Doppler Current Profiler), Hydrophone and Bottom Pressure Recorder.

Meanwhile, the ship cruised slowly along a survey line to measure water depths and currents with its own multi-beam sonar and ADCP. If it hadn't been the middle of the night, we could have seen some stunning sights of the coastline. At the end of this survey, the ship also performed a CTD cast with water sampling.

Towards sunrise, the IP looked quite respectable again. All instruments were checked to see if they successfully responded through a test cable when talked to, and final touches were applied to ensure that everything was ready for redeployment.

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ROPOS lifting off with cleaned and overhauled IP to redeploy at Folger Deep.

Redeployment on the seafloor went smoothly, and after connecting the IP back to the main cable, our shore team confirmed that data were streaming in again. For calibration of the echo sounder, ROPOS hovered 40 metres above it at for awhile. After taking several mud and water samples in the murky waters, ROPOS returned to deck, and the two pilots were relieved of their duties, departing via another ride in the Zodiac. We used the opportunity of our journey back out to deep sea to conduct another survey with the ship's multi-beam echo sounder and ADCP at Barkley Canyon. Hopefully, we will set foot on land the next time we come so close to shore.

Barkley Sparkling

Barkley Sparkling

By Martin Scherwath

Admittedly, the seafloor around Barkley Canyon is perhaps not quite as versatile and exciting as the Endeavour site. Nevertheless, considering that the Barkley seafloor consists mostly of grey mud with a thin layer of more recent brown deposits, it is not at all boring: Flora and fauna are plentiful on the seafloor, and even the water column often seemed to sparkle from many small fish reflecting ROPOS' lights during descent and ascent. And so, during the dives, sometimes the dive video loggers could not keep up with describing what came to view.

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Shellfish remains and tiny crabs on the Barkley Canyon seafloor.

As normal with NEPTUNE Canada's maintenance missions, many dives were planned to recover, redeploy or newly install our ocean floor hardware. But this time was a little unusual as we were not entirely sure what to find on the seafloor. This was because in February the two instrument platforms (IPs) at the upper slope (400 m water depth) stopped talking to us, and some instruments equipped with tilt meters inside reported some extreme turning before they stopped (indicating a potential fishing trawler encounter). It seemed clear that we would find some damage. And so, our first dive was to inspect how it looked around the locations of the upper slope IPs and their attached instruments. See Barkley Upper Slope blog for a description and pictures of our seafloor findings.

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Sediment trap standing happily upright next to the overturned Barkley Benthic Pod #2.

While the images from the Upper Slope inspection dive were being analyzed and a clean-up and recovery procedures were being established, we moved a little further down the slope to our other Barkley Hydrates site (800-900 m water depths). Here, we continued with more typical maintenance and deployment where damage was not an issue and we knew where things should be and in what state we would find them. Among other things, we recovered Wally II, the seafloor deep-sea crawler from Jacobs University in Bremen, Germany, for maintenance. Wally normally crawls around a gas-hydrate mound, where natural gas (mostly methane) is bound in ice-like crystals just below the seafloor; hence, we call this site Barkley Hydrates. Wally II takes pictures and various measurements along its path throughout the whole year. But like most vehicles, Wally II needs servicing once in a while, and after some inspection on deck it is now coming with us to shore.

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Wally II being loading into the ROPOS tool basket on the seafloor.

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Wally II emerging from the water for servicing.

The images from Barkley Hydrates clearly showed us just how active gas-hydrate structures are. We saw some bubbling from dissolved gas, drops from oil leaking out of the seafloor, and the continuous hydrocarbon feast around these natural resources benthic community, an enjoyable prospect to researchers.

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A shark glides by Wally's tracks near a couple of way markers in "Wallyland."

We also took plenty of mud samples (read mud blog to find out why grey can be exciting) in the form of push-cores, filled plenty of water bottles attached to ROPOS, and scooped up some mussel shells for scientific sampling. And when ROPOS returned onto deck, we even lowered the ship's CTD (conductivity, temperature, depth (pressure) sensors) attached to a rosette of more water bottles to sample the water column.

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Push-core sampling on the seafloor and a hagfish lingering by the flipped Instrument Platform.

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Our sediment trap after recovery to deck, as viewed from below.

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James Stephaniuk and Kira Homola carefully extracting water for oxygen analysis from the CTD and water sampling rosette with its grey Niskin bottles.

After the initial inspection dive was analyzed, the scene was set for the clean-up that followed. The over-turned IPs were put on their feet again, instruments and cables were collected and recovered on deck, cleaned and partially dismantled. We are bringing them home for more thorough inspection and re-fitting. The detached main cable was repaired by bringing its broken end on deck while leaving the rest of the cable dangling 500 m down to the seafloor. A clean cut and proper termination put the cable back into a working condition, to be re-fitted with a new connector and hooked up to the main cable hopefully during our next cruise in September.

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Cutting and preparing broken cable, for refit and reconnection on a future cruise. From left to right: Steve Mihály, Kim Wallace, and Jonathan Zand.

Not everything worked out perfectly though, for example, a heat sensor and a temperature probe array we deployed on the seafloor did not perform as we hoped, so we had to recover them. But at the end of the Barkley Canyon leg of our cruise, we left the seafloor instrumentation bright and sparkling, and our shore colleagues confirmed nice data streaming in again. Good news, and so we allowed ourselves to enjoy a stunning sunset that one can only admire at sea.

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Sunset over the Pacific Ocean.

Tales from the Mudman

Tales from the Mudman

By Rénald Belley

My name is Rénald Belley and I'm a PhD student in marine biology at the Memorial University of Newfoundland. I'm part of the Canadian Healthy Oceans Network (CHONe), a partner of NEPTUNE Canada. This partnership gave me this great opportunity to come aboard the R/V Thompson to sample some of the NEPTUNE Canada sites. Using the remotely operated vehicle ROPOS, I collect and study deep-sea soft-sediments, a.k.a. mud. For this reason, I'm now known on board as the Mudman.

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Kira Homola and Rénald Belley with a glorious sample of mud.

The main reason why I'm interested in the animals that live within the sediment (a.k.a. infauna) is that approximately 70% of Earth's surface is covered by oceans and that most seafloor areas are soft-sedimentary habitats. This means that soft-sedimentary habitats are the largest on Earth! This being said, deep-sea soft-sedimentary habitats lying below 200+ meters of water are heavily under-studied. We know very little about the animals that live in this mud and most of the species living there remain unknown to science. In fact, most estimates show that 99% of the bottom-living (benthic) species are still unknown. Therefore, these soft-sedimentary habitats represent a large pool of unknown biodiversity and one of my goals is to extend our knowledge of these species a step further. To do that, I'm studying the interactions between these animals and their environment, in other words, how the species living in the mud influence their environment. By doing so, I hope to shed some light on the importance of these animals to their ecosystems and for the well-being of humans. This study will ultimately help us to better protect and sustainably use our oceans.

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A skate, nudibranch, sea pig, and some brittle stars

If this interests you, stay tuned to the NEPTUNE Canada blog. I'll tell you more about these amazing creatures living in the sediment and how we collect them with ROPOS, one of the world's most advanced remotely operated vehicles.

Sampling Sideshow on flickr

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Life Aboard the RV Thompson

Life on Board

By Kira Homola

Do you enjoy large amounts of delicious food three times a day? Playing ping-pong when the floor is moving beneath you? Watching movies and playing games with your friends? Reading a relaxing novel while staring out over the beautiful ocean?

Then life aboard a research vessel is for you!

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Fine company for the R/V Thomas G. Thompson.

In between shifts of logging, piloting, fixing, navigating, and sampling, the shipboard residents of the Thomas G. Thompson still find time for fun, relaxation, and, occasionally, laundry. We live two to a room, four to a bathroom. Each room is equipped with ample cabinet space, chairs, a sink, a mirror, and two lovely bunks with individual reading lights. Between every two rooms is a bathroom that includes a toilet and shower, difficult to use during rough seas, but thankfully there is an emergency handle handy.

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Kim Wallace prepares the temperature probe array for deployment at Barkley Hydrates.

On board, we are divided into three groups: crew, science party, and the ROPOS team. The crew is in charge of keeping us on course, helping with the launch and recovery of instruments, and making sure the ship is running perfectly. The science party can be divided into the engineers and the ROPOS lab team. The engineers are stationed in the main lab and spend their time preparing instruments for deployment, and repairing, maintaining, and downloading data from the instruments we recover. The ROPOS lab team, the chief scientists and us loggers, communicates with shore, logs events during the dives, streams video life to the internet, and takes photos. We are also the ones who take and process samples, including everything from boxes of sediment to bottles of water to tubes of mud. The ROPOS team spends their time maintaining, deploying, recovering, navigating, and piloting the ROV. Overall, the sheer amount of activity on board is amazing: you can walk into any lab in the middle of the night and there will still be a group of tired people working away. Our 24-hour operations keep us very busy, but watching the dives and handling the samples is fascinating work, so I don't mind.

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Maryann with samples of mud.

Personally, rocking boats put me to sleep, so I'm rarely wide-awake during my actual working hours. My leisure time is about half sleep, but that still leaves a bit of free time for socializing. While on board, I have had my rear end handed to me playing scrabble against the head cook and other members of the crew, science team, and ROPOS team. I have also been taught Cribbage, a bad game to learn while only half awake: it's very hard to add to 15 sometimes, people.

As everyone on board is very friendly, the ruling ping-pong champions have taken the underling players (such as myself) under their wing. After my first few days of falling, tripping, hitting myself in the face with the ball, and serving like a girl, I have been transformed into a hard-core, intense, spin-balling ping-pong champ. Not really, but I can actually get the ball into the right box most of the time, so that's quite an improvement. I especially enjoy the occasional doubles game, played to the intoxicating sound of our Chief Scientist's accordion. A very difficult instrument to play, I now realize, but one that is very fun to listen to.

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Ping pong and accordions: What could be better?!

We are not lacking for musical talent on board, as a matter of fact. In addition to our accordion queen, we have a stunning flute-playing Able Bodied Seawoman on board, who can also spell better than anyone except the cook, as well as a guitar playing chief engineer. Satellite radio is always blaring from the ROPOS corner of the ship, accompanied by the sometimes questionable singing voices of the ROPOS team and, from time to time, myself.

For those of us that work in the ROPOS lab, we spend 8-12 hours a day staring at more screens than I've seen in the same room my entire life, including the TV store. Apparently watching undersea footage just can't compare to Talladega Nights, though, as everything from Will Ferrell to old westerns are playing around the clock upstairs in the lounge. Not counting the VHS movies, there are exactly 1008 numbered DVD's in every genera available for viewing. Across the hall in the library are 5 floor-to-ceiling bookshelves full of novels ranging from Ann Rice and James Patterson to an autobiography by a Country-Music-Singer/Comedian and a tour book about Tahiti.

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The Control Room.

In conclusion: being on board and unable to walk down a hallway without feeling like a yo-yo is a complete blast. Though everyone on board slightly resembles a zombie at this point in the cruise, we are all enjoying our science and our play, but most of all, our food and our sleep!

Damage Sustained at Barkley Upper Slope

On July 12, 2011, the R/V Thompson arrived at Barkley Canyon. The much anticipated first dive was dedicated to inspecting and assessing the damage at Upper Slope (Dive R1431), one of over 15 study areas on the NEPTUNE Canada network. Communications were lost from Barkley node to the Upper Slope and Pod #2 instrument platforms and all connected instruments on February 18, 2011, and since then, the state of the equipment was completely unknown - staff members at NEPTUNE Canada were not even sure we would find our equipment on the sea floor!

Overview of Barkley Canyon

Barkley, a submarine canyon, is an important region for studying nutrient and sediment transport between the shelf break and the deep sea. Scientists are studying benthic (seafloor) ecology using instrument suites at four "Pod" sites on the upper slope away from the canyon (400m), mid-canyon wall (900m), and canyon axis (1000m). Long-term monitoring will allow scientists to follow the seafloor response to pulses of food from the phytoplankton blooms of the surface waters, and observe changes in seafloor communities related to seasonal patterns of sediment transport and nutrient upwelling.

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Overview map of Barkley Canyon

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Overview map of Barkley Upper Slope

The upper slope location was home to two instrument platforms. The Barkley Upper Slope instrument platform, host to an acoustic current profiler (ADCP) and a conductivity, temperature, depth gauge (CTD), and was additionally was connected 3 satellite instruments: a broadband seismometer, bottom pressure recorder (BPR), and a hydrophone.

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Barkley Upper Slope Instrument Platform - as installed

The Pod #2 instrument platform (the upper slope pod mentioned above), had a rotary sonar for acoustic seafloor imaging, an acoustic current profiler (ADCP), an aquadopp current profiler and a black & white video camera on board, and was connected to a satellite sediment trap.

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Barkley Upper Slope Pod #2 - as installed

Findings on the Sea Floor

When ROPOS arrived at the bottom, it was immediately evident that something was wrong. The first pieces of equipment we saw were cables. The 9.875km cable which connects the Upper Slope platform to the Barkley node had obviously been disturbed - it is normally buried in the sediment to protect it from fishing trawlers, but it was laying on top of the sea floor. ROPOS followed the cable and discovered that the end had been pulled out of the termination can. A second cable was also visible which was also broken off from its end.

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Broken Cable

Next, ROPOS followed the extension cable to the bottom pressure recorder (BPR), part of the NEPTUNE Canada tsunami array. The BPR was still connected to its cable, but was laying on its side. An octopus had taken up residence and layed her eggs on it as well.

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A Small Snuggly Octopus and Her Eggs on a BPR

We followed the cable toward the instrument platform, and found that the other end of the BPR had also been ripped out of its termination can. At this point, it was time to try to find the instrument platform itself. In Victoria and around the world, NEPTUNE Canada staff and scientists were gathered around monitors after hours to watch this spectacle unfolding. As the Barkley Upper Slope instrument platform came into view, it looked more like a rock fish habitat than a piece of scientific equipment! It was lying on its side with one foot missing and disconnected cable ends beside it. The legs were serving as an octopus condo, with a resident in 3 out of 4 legs!

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Barkley Upper Slope Instrument Platform - as inspected

We continued the survey, and the next instrument brought a bit of optimism. The broadband seismometer was still buried, the sediment above it looking undisturbed. We have not been able to test it, but our engineers are hopeful that it might still be operational.

The Pod #2 instrument platform was not so lucky. We found it upside-down, with the normally downward facing benthic camera looking into the water column. Amazingly, the sediment trap was standing upright beside the platform as if nothing had happened.

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Barkley Upper Slope Pod #2 - as inspected

Recovery and Repair

Over the course of several subsequent dives, the damaged equipment was brought on board the R/V Thompson. Righting the upturned platforms, necessary so that ROPOS could connect to them and ascend, was challenging. Engineers on board have brought the damaged cable end on deck to better assess damages and stop any water ingression inside the cable structure and ensure its integrity in anticipation of the eventual repair. This necessitated unburying approximately 700m of cable so that the end could be raised to the surface. ROPOS achieved this by spending over 8 hours vacuuming sediment to expose the cable in a trench.

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ROPOS Vacuuming

Consequences for NEPTUNE Canada Operations

One very disappointing consequence of the damage at Barkley Upper slope was that we are not yet able to deploy the Vertical Profiler System (VPS). The VPS is a custom designed instrument which consists of a seafloor platform and a motorized tethered float which is host to a collection of instruments for monitoring processes in the water column such as the transport of productivity from the surface to the deep sea. It will periodically scan the entire water column by raising and lowering the float several times per day. The VPS was successfully tested at the Ocean Technology Test Bed in Saanich Inlet earlier this year, and is ready for deployment.

So far, we have lost 5 months of valuable data from the site, and it is unclear how long it will be before the site can be brought back to operation. Right now, the biggest question is whether the almost 10km cable to the node is reparable, but the state of most of the other equipment is still unknown. In addition to the scientific cost, the monetary cost is significant. Equipment will need to be repaired and replaced; days of ship time which could otherwise be used for connecting new instruments were sacrificed; and significant staff time has gone into the planning and execution of the recovery operations.

On a positive note, we did find all the "silent" equipment on the sea floor. We are hoping some of it might be salvageable, and that it will be redeployed and transmitting data again in the near future.

MEF Testing

Testing at Main Endeavour Field

One of the most exciting accomplishments of the Fall 2010 installation and maintenance cruise on the R/V Thompson was the successful deployment of instruments at the Main Endeavour Vent Field (MEF). After laying a 6 km cable across the precipitous mid-ocean ridge terrain from the node to the instrument platform site, five unique instruments were deployed: a short-period seismometer, BARS (Benthic and Resistivity Sensor), RAS (Remote Access Water Sampler), COVIS (Cabled Observatory Vent Imaging System) and an HD video camera. The HD camera developed problems shortly after deployment and had to be retrieved, but the other instruments were fully operational, providing researchers with unprecedented real-time data and a new perspective on this fascinating region.

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Example of data from COVIS.

Unfortunately, the month of October brought an unwelcome development. On October 20th, communication from the shore to the junction box on the MEF Instrument Platform was lost, and the instrument data streams stopped. One of the principal objectives of the July 2011 installation and maintenance cruise was to visit MEF and perform some underwater detective work to determine what went wrong at Main Endeavour.

Engineers developed a test plan with several contingencies: The first step was to test the junction box using a specially-designed testing kit which was sent down with ROPOS. If the junction box was found to be faulty, a new junction box and instrument platform was ready on the ship for replacement. If it was found to be operating properly, then some diagnostics on the cable would be performed. If communication could not be restored through the cable, then the individual instruments would be tested using test protocols supplied by the researchers responsible for the instruments. A test result showing a faulty cable would mean that MEF could not be brought online until September due to the necessity of installing a replacement cable. Unfortunately, this turned out to be the conclusion of our engineers.

On visual inspection, one of the cables which was supposed to be oil filled appeared very flat, which could put pressure on the optical communication fibres.

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We punctured the oily to see if seawater would seep into the cable and relieve some pressure on the wiring.

In a last ditch attempt to salvage the cable, we tried poking hole in the "oily," to allow water to seep in and relieve pressure on the fibres. We tried puncturing the oily in several places with an awl, but unfortunately nothing happened. Based on these results, the installation of Tempo-mini will have to be postponed to September when we will have a new cable to replace the one currently installed. However, the good news from the tests is that the existing junction box, RAS and COVIS have all been confirmed to be working, and are ready to begin streaming data again whenever communications are restored.

Tubeworm Sampling

Tubeworm Sampling

By Nathalie Forget

One of the objectives of the July 2011 NEPTUNE cruise was to get samples of the tubeworm Ridgeia piscesae from the Main Endeavour Vent Field on the Juan de Fuca Ridge. This tubeworm is the foundation species of the ecosystem at this location, providing habitat, protection and food for other animals.

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Sampling fat tubeworms at a hot vent.

R. piscesae is a polychaete of the family Siboglinidea. Its body is divided in four major regions: the anterior part that bears the red branchial plume (gill structure) and serves as the gas exchange area; the vestimentum, a very muscular region on the backside of the worm and enfolding the gonopores (reproductive cells); and the trunk, which contains the gonads and a very particular organ called the trophosome. Inside the trophosome live sulphide-oxidizing symbiotic bacteria providing food to the tubeworm, which has no mouth or digestive system and therefore relies completely on these symbionts. The posterior region bears chaetae (bristles) to anchor the worm to the surface of a chimney.

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Colony of tubeworms

Living in highly variable environmental conditions, R. piscesae was first described as two different species (and some even suggested there might be up to 5 or 6 different species!) because of its surprising variability in phenotype (observable characteristics). In environments of vigorous and steady hydrothermal fluid discharges, where the temperature is around 30°C and the sulphide concentration is high, the tubeworms bear bright red and well-furnished branchial plumes and white short-fat tubes. When the discharges are more diffuse and the temperature and sulphide concentrations are lower, the colour of their branchial plume is pink, the filaments having been grazed by other species of worms (e.g. scale worms), and their tube is yellowish, long and skinny looking.

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Ridgeia piscesae

The purpose of this tubeworm sampling is to compare the microbial communities living inside their trophosome (the host organ for symbiotic bacteria) in contrasting environmental conditions. The long-skinny morphotype (variety) was collected last year. During the NEPTUNE cruise, we completed the sample collection by getting the short-fat morphotype. ROPOS took temperature measurements at the base and the plume of the tubeworm bushes using a temperature probe, and collected a grab of worms using its remotely operated arm. Once on deck, the sample was put in seawater buckets and prepared for future DNA extraction: their tube was carefully removed and their trunk was frozen at -80°C.

Other Siboglinidea typically possess only one phylotype (evolutionary classification) of symbiont. However, a recent study suggested up to 5 different symbionts in R. piscesae. Preliminary results from research by NEPTUNE Canada maintenance cruise participant Nathalie Forget also point to more than one phylotype in this tubeworm species. Having a diversity of symbionts could be an adaptation to extremely variable environmental conditions, allowing the tubeworm to get nutritional resources in contrasting habitats.

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A black smoker and chimney.

Successful BARS Recovery

BARS Recovery: A Great Success!

On July 9, 2011, we recovered the Benthic and Resistivity Sensor (BARS), a cruise objective because of its failed hydrogen sensor and an isolation fault that disrupted its communication to the Main Endeavour Vent Field (MEF) instrument platform. The isolation fault was detected on the instrument on October 20, 2010 before the MEF junction box stopped communicating, just one month after installation. During inspection of the BARS cable, scientists discovered that the reason behind the isolation fault was the growth of a vent chimney directly on the implicated cable, melting the hose and exposing the inside wires directly to the environment! Gastropods had also started growing on the cable.

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The damaged BARS cable.

What the BARS Instrument Measures

In September 2010, the BARS instrument was installed at a depth of 2189.0 metres at the MEF Grotto site. It has sensors to measure resistivity, temperature, eH (oxidizable nature of seawater components) and hydrogen within black smoker vents, where temperatures of the emerging effluent can reach 350°C. BARS uses a probe inserted directly into the hydrothermal vent in order to measure the pure vent fluid as it comes out, before diluting in sea water. BARS data are available via our Data Search and Plotting Utility. See summary of current BARS research by Olson.

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Vent Temperature(BARS, red curve) and Pressure (ACM, blue curve)

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Vent Temperature (RAS, magenta curve) and Pressure (ACM, blue curve)

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Temperature (BARS, red curve) and Temperature (RAS, magenta curve)

The scientific events detectable by the BARS instrument include several scales, from a single earthquake to a swarm of earthquakes, a dike intrusion, or a seafloor eruption. An event could be indicated by a small sudden temperature change (+ 3°C). Changes in the resistivity sensor (i.e. the mixing ratio among vapor, brine, and seawater) or in the hydrogen sensor (i.e. concentration) could be caused by an earthquake or intrusive lava event. The eH sensor would respond to changes in the concentration of reduced chemical species in the fluid (e.g. hydrogen sulfide).

Recovery Operation

Any operation is delicate when dealing with temperatures as high as 320°C, but especially so when your ceramic probe is super sensitive to rapid temperature change and lodged inside a vent plume over two kilometers beneath the waves. The ROPOS crew had to be extraordinarily careful and patient not to break the BARS probe during recovery. Principle Investigators, Dr. Marv Lilley and Eric Olson (both from the University of Washington), gave special instructions to mitigate the chance of breaking their instrument during the recovery operation at the Endeavour Grotto site.

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ROPOS carefully pulling the BARS probe out of the hot vent

Luckily, the ROPOS pilots were able to grab and gently pull the probe out of the 320°C vent plume without causing damage. In order to minimize heat shock to the ceramic part of the instrument, ROPOS pilots delicately removed the sensor tip from the black smoker fluid. The slow cooling process of holding the tip one foot from the black smoker orifice for a full minute, and retreating from the heat source at the same rate three times was a deemed as a reasonable approach by the PIs. We are happy to report it was a smooth operation.

The instrument will be brought to the University of Washington to be refurbished. Plans are to redeploy the BARS instrument at MEF in September 2011 along with a second BARS instrument at Endeavour Mothra Vent Field.

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BARS in-situ.

Piezometer Installation

Scientists from Canada and France began deploying a cabled piezometer at 9:45 am (PDT) on Wednesday, July 6, 2011 at the ODP 1027 node of the observatory. This is the first operation of the NEPTUNE Canada July 2011 installation and maintenance cruise on the R/V Thompson. In visible company was the R/V Atlantis, the sister ship of the R/V Thompson, with a crew of researchers working on nearby Ocean Drilling Program (ODP) boreholes, an illustration of the high interest in the thin oceanic crust of the Juan de Fuca tectonic plate.

The needle-like probe of the piezometer is six centimetres in diameter and is equipped with four pore pressure and four temperature sensors distributed along its four metre length. The piezometer can measure differential pressure between the pressure in the sediment and the water column. Scientists are interested in comparing these pressure variations with other events such as nearby earthquakes and groundwater flow. Piezometers, therefore, expand areas of pore pressure measurements, which complement borehole measurements.

The Ifremer-developed piezometer was lowered down 2560 m using the ship's cable rolled out on the A-Frame on the R/V Thompson. It was dropped at a rate of one metre per second for the final one hundred metres, where the momentum of its 999 kg "piezo-head" pressed the piezometer probe four meters into the sediments. It was a delicate operation performed from deck, involving both NEPTUNE Canada staff and ship crew. Navigating the probe almost three kilometers to the ocean floor on a single wire from a large ship was extremely challenging, and transponders had been placed on valuable assets already on the seafloor to ensure that they would not be skewered. It was a close call with a recently decommissioned cable that will be recovered next year.

During the deployment, the instrument was running on rechargeable batteries and logging data into internal memory - with a capacity for two years of data sampled in one second intervals. The raw data has been collected by the piezometer, including the data which covers the crucial deployment phase. This data is essential for calibration purposes and will become available for viewing via Oceans 2.0.

After the piezometer was lowered, ROPOS descended for two and a half hours to the seafloor. During this dive, ROPOS caught images of sea cucumbers, jellyfish, and salps. After checking the distance between the instrument platform and the piezometer (fifty metres), ROPOS was ready to connect the instrument to a cable running between the piezometer and the ODP 1027 Instrument Platform. At 02:39:51 UTC, the connection was made and data is flowing into our archive!

Slideshow on flickr

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