Second deployment failure

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Abyssal Eats, Trip Advisor Review (1 Star): “Outrageous! The food smelled great but the waiter flipped my table over, trapping it against the filthy floor. I spent the next half hour listening to tiny amphipods eating at my expense. If I could give 0 stars I would.”

Author: Rob Harbour

The eagle-eyed among you may have noticed that in one of the pictures in the gallery showing the lander being lifted out of the water after its first deployment, the bait plate is hanging by only two of its cables. While the lander was being thrown around in the waves on the surface for 30 mins before bringing it back on board, one of the cables was ripped from its adjustment clasp, which had become corroded.

We spent some hours reattaching the broken part with a metal crimp and adjusting the bait plate and camera field of view, ready for a second go. Unfortunately, when the lander returned after 36hrs it was yet again hanging by only two cables, and worse, the tuna was suspiciously intact. We suspected the cable had come loose on the way down and flipped the bait plate fish-side-down on the sediment; sadly the video confirmed our fears. It seems the force of the initial drop into the water broke our repaired cable in another place, further down on a different corroded clasp.

We are obviously very disappointed with this result, especially after such a successful first deployment. That the cable came lose seconds after deployment is especially galling, if only we could have known!

We should of course look at the positives here, the lander release system worked perfectly, as did the radio beacon, which turned out to be essential for its recovery this time in poor visibility due to torrential rain. We have the expensive bits back and can have another try, that’s the main thing! Today we will remove and replace all of the bait plate cables, simplifying the configuration to avoid any more disappointingly inaccessible dinners for fish.

The lander will be deployed again for 36hrs from 8pm this evening, we hope to return with better news soon.

Our lander returns to surface!

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Just over 1kg of fish was eaten over a 24hr period. Image credit: Robert Sommerfeld

Author: Milena Wales

And so, after triple checking every element of the lander and its weight release system, we were finally ready to send it off on its first journey the abyss, complete with a 1.5kg tuna fastened to the bait plate.

The maiden voyage to the deep started shortly after lunch on Saturday afternoon to a crowd of excited onlookers. Most of the scientists and crew were well aware of the trials and tribulations of our lander and were keen to see it off.

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Milena and Rob very happy to receive a signal from the release saying it was on its way.

We went to collect it with trepidation after 24 hours and to our utter joy, we were able to communicate with the onboard acoustic releaser. We quickly confirmed that it was on its way to the surface at the heady speed of 59 m/minute. It took less than 3 hours from the first call to the lander to have it safely back on deck.

To our delight, the tuna was almost entirely eaten by scavengers and we were keen to look at the video to find out what devoured it. The camera had successfully filmed the progress from whole fish to the almost complete skeleton. The bait attracted a variety of deep-sea scavengers from tiny amphipods, to large red shrimp, although the bulk of the flesh was eaten by large fish called rat tails, while eelpouts seemed to lay on the bait plate uninterested.

You can see more pictures from the deployment in the gallery to the right, including some stills from the video recorded by the lander.

The “Anonyx” lander

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The components of the “Anonyx” lander

Author: Rob Harbour

Named after a genus of Lysianassid amphipod, small shrimp-like crustaceans commonly found on the deep-sea floor, the Anonyx lander was developed to photograph scavenger behaviour at depths of up to 6000m. Here in the Pacific we’ll be deploying it to a depth of around 4500m. To put that in a terrestrial perspective, you could fit all but the very tallest of The Alps underneath our ship right now. At this depth, the pressure is around 450 times normal atmospheric pressure and the temperature is just 1.5 degrees Celsius. Despite these hostile conditions (hostile for humans at least!), we expect to be able to film considerable numbers of mobile scavengers, including deep-sea fish, shrimp, crabs and of course, Lysianassid amphipods.

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80 kg of recycled anchor chain attached to one of the lander legs

The lander is comprised of a metal frame, attached to which are twelve glass floats that offer buoyancy while resisting extreme pressure. When the lander is deployed, 80 kg of weight is attached to each leg with an acoustic releasing system. This weight allows the lander to sink to the seabed and remain there whilst the HD video camera records the scavengers attracted to the fish on the bait plate. After 24-36 hrs, we will signal the acoustic releaser with sonar, it will open a clasp, dropping the weights to bring the lander back to the surface using the floats. We expect the lander to return relatively close to the ship (within 500m), but it also has a radio beacon that we are able to track directionally from the bridge, as well as a bright strobe light in case it’s dark.

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This bait was deemed more ethically questionable than using tuna

For bait, we are using whole albacore tuna. This wouldn’t have been our first choice, due
to sustainability issues with tuna (albacore have ‘near threatened’ status), but it is important to use a pelagic, oily fish and there was a limited selection at the Guayaquil fish market. We will watch the footage from the HD video camera, noting the point at which the bait lands on the sea-bed, and then the point at which the tuna has been reduced to a skeleton. This allows us to calculate a scavenging rate for a particular deployment area.

A little snag
The lander is designed to support one or two acoustic releases. We would normally like to deploy it with tandem releases, meaning it would have redundancy if one of the releases fails. Unfortunately when unpacking after our arrival in Ecuador, we discovered that one of the releases has flooded with oil from the transducer head. After contacting the manufacturer we’ve been told that it cannot be used (KUM have offered to fix it for free when we return). To reduce risk, we have decided to test the working release on its own by attaching it to another piece of equipment. Provided the release survives its trip to 4500m this evening, and we are successful with our attempts at communicating with it on the bottom, it’ll be put back on the lander ready for the real thing.

Our first deployment will be Saturday lunchtime, if all goes to plan I should be able to post some stills from the video soon.

 

Life aboard the RV Sonne: the transit to the CCZ

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Beautiful, calm weather from the front of the RV Sonne.

Author: Milena Wales

A total of 23 scientists and 31 crew, including the captain, will live and work together for 53 days. Thankfully we all have our own well-equipped cabins, which I am told is a luxury on research vessels.

Life aboard the Sonne quickly settled into a routine of mealtimes, preparing equipment for deployment, getting used to the intense heat and sun, and socialising.

As the vessel is German, mealtimes are highly regimented and we’re told German punctuality is appreciated! The food is delicious, albeit generally dominated by (red) meat so it could be a bit of a challenge to stay trim. Unless, of course, one is willing to endure pain in the so-called “recreation room” – a euphemism used for the gym.

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Captain Lutz’s 60th birthday party.

Before our first week on board was over we celebrated two birthdays – one for an engineer and the captain’s 60th birthday. The latter was a full day of rest and partying. It kicked off with the scientists singing Happy Birthday in 5 languages followed by a champagne toast, and culminated with an evening of dancing until the early hours of the morning. The captain was presented with a lovely wooden plaque, made by his crew.

We have so far been blessed with calm, glassy seas and while passing about 170 nautical miles north of the Galapagos islands, we acquired some additional passengers – the archipelago’s infamous boobies (of the feathered variety). They have been performing fantastic aerial displays as they dive and swoop over the water, to sweep up flying fish fleeing the noise of the ship. Of course, they have also been the source of many puns and innocent misunderstandings, related to ladies’ swimwear wardrobe malfunctions. We do wonder whether the same jokes will remain funny until we get back on dry land..

Our lander arrives!

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Professor Andrew Sweetman, Milena Wales and Rob Harbour stand next to their long awaited container.

Author: Rob Harbour

I have discovered over the course of the last three months that freight shipping is fraught with stress, complications and what we might call dynamic costs. Stranded in Columbia for a week, it looked like our container may not even arrive in time for departure. But we’re here, our lander is here and loaded onto the RV Sonne; the past three months in my assumed role of Freight Manager have not been for nothing! To say we are all relieved is an understatement.

It’s time to unpack our equipment, settle into our cabins and prepare for the adventure and the scientific discoveries that lay hidden beneath the vast Pacific Ocean.

Pacific cruise on the RV Sonne

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Milena Wales and Rob Harbour, both PhD students at the Lyell Centre, Heriot-Watt University, will be updating this blog as they make their way across the Pacific Ocean. They will join the RV Sonne in Guayaquil, Ecuador, departing for the Clarion Clipperton Zone. There they will deploy a benthic camera lander at between 4000-4500m depth to record the scavenging behaviour of deep sea animals; something that has never been done before in this area. They will spend a total of 53 days at sea, sailing 7000 miles, before arriving in Suva, Fiji on 29th May.

Please check back for regular updates!