Back to sidescan whilst the camera takes a well-earned ‘rest’

Well, unfortunately our camera was in a slightly worse condition than everyone thought, leaving two options: a) a DIY repair, or b) heading into Scrabster to pick up and replace the damaged parts – a 20 hour round trip...

Whilst we wait to see what the very capable engineers on board can do, we hooked up the sidescan to continue surveying the lumps and bumps of the Faroe-Shetland Channel seabed. Sidescanning around the clock certainly took it out of the scientists on board, but reaped some reward.

By processing the sidescan before continuing with video camera work we have been able to target key areas of interest. These include particularly rough grounds dominated by boulders and cobbles, sediment wave fields that appear as large expanses of ripples on the seabed, and areas where trawl marks may be present. This presents the opportunity to sample communities of the Faroe-Shetland Channel in a range of environmental conditions. 

Sidescan interpretation

With sidescanning and interpretation complete, it was time to take the plunge with the DIY repair on the camera. A tube of araldite later and we were ready to go. Everyone stood nervously on deck and bridge waiting for a fuse out. Luckily hovering at 100m depth seemed to cause no problems and so we cautiously lowered the camera to the depths we would be using it at – between 450-500m. So far so good, the DIY repair job seemed to have done the trick!

Testing the repair job on the towed camera

Vivid blue sponge encrusted rock with lamellate sponges, branching sponges,

squat lobsters and pencil urchin

With camera work back on track it was back to 12 hour rotas and a continuation of mapping the extent and distribution of deep sea sponge grounds in the Faroe-Shetland Channel.

Sunrise on a day of survey work

Riding the sponge belt

A short transit from the Wyville Thomson Ridge saw us at our second and final study area – the Faroe-Shetland Channel which is of particular interest to Marine Protected Areas work in Scotland. The ‘Faroe-Shetland sponge belt’ MPA proposal has been identified primarily for its aggregations of vivid yellow and white deep sea sponges, known to Faroese fishermen as ‘ostebund’ or ‘cheesy bottoms’.

These dense sponge aggregations, which can reach numbers of up to 4-5 individual sponges per m2, are thought to be situated around the 400-600m depth mark and often found in association with iceberg ploughmarks which provide settlement points for the sponges. We have records of the deep sea sponge aggregations habitat towards the eastern extent of the MPA proposal, but want to see if these numbers are present towards the west of the channel.

Video tow work began in quite an exploratory fashion, with 1km long video tows planned at approximately 5km intervals between sampling stations selected randomly between 400-600m in depth. Unfortunately, just as occasional sponges were starting to appear on the video feed , the camera took a bit of a turn for the worse and needed some maintenance before it went anywhere near the water again. Fingers crossed for a quick repair!

Sponges

Coarse and shelly sediments

Sediment ripples

Featherstars and anemones on rock

In the meantime, we’ve been using the onboard grab sampling equipment to take some samples of the seabed at previously video surveyed locations. These samples will be used for analysis of the sediment types present and the animals living within the seabed. We’ve also been setting up the sidescan sonar device for deployment to help us generate a picture of the lumps and bumps of the seabed we're videoing and taking grab samples of. This will help us to better identify the iceberg ploughmark zones previously mentioned where sponges like to settle and hopefully better target our camera work.

Rockin’ and a rollin’

Excellent sea conditions have enabled camera work to continue around the clock. At the Wyville Thomson Ridge we have been busy surveying the stony reef communities at various depth zones right across the south-western part of the site. Adding to the 10 video tows from yesterday, we have now completed a further 19 giving a total of 29 tows.

The type of beasties we’ve seen at the Wyville Thomson Ridge are considered largely typical of stony reef communities at these depths, and have included the bizarrely shaped pencil urchin, more squat lobsters than you could shake a stick at, and masses of vivid coloured encrusting sponges. We’ve also had a few fishy visitors, including chimeras, ling and a red banded fish chilling out on the rocks.

Chimera with rocks and yellow encrusting sponges

A few particularly special video tows came at the end of the day shift today when we visited some locations within the Wyville Thomson Ridge SAC surveyed by other scientists several years ago. We wanted to do some repeat work here to see if similar communities were still present. We certainly weren’t disappointed, with beds of cup corals, sponges, countless featherstars and the delicate framework building cold water coral reef Lophelia pertusa all present in force.

Cold water corals and sponges

Having ended our time at the Wyville Thomson Ridge on a high, it was now time for a short steam to hopefully have similar luck at our second and final study area – the Faroe-Shetland Channel.

Sidescanning within the SAC is finished

We’ve been really lucky with the weather so far, considering the forecast at the beginning of the week. Bad weather is all around us (Force 11 in the Faroes not that far North of us) but we are still in (relatively) calm water in the eye of the storm.

Having finished the sidescan sonar lines on Wednesday 31st October at 10:30pm, we spent the night checking sea conditions as it had become too rough for camera work. By morning the wind and swell had calmed enough for us to start the first of the camera tows, lowering the video and stills cameras on their frame to the seabed, between 400m and 800m below us.  The aim is to hover the camera frame at about 1.5m off the seabed whilst the boat drifts slowly along. 

Towed camera deployment

Once the ship’s crew have got the camera to the seabed, in our office below decks, three or four people watch the video monitor.  One person makes fine adjustments to the height of the frame off the seabed with the winch as the boat drifts along – but in the 3-4m swells we have been experiencing, this is just about impossible. One person presses a button on the laptop to take still photos approximately every 20 seconds.  However, as there is a slight delay between pressing the button and the camera at the seabed responding, you need to press the button a couple of seconds before the camera is at the right height, and before it hits the bottom as a result of the boat rocking in the swell – not as easy as it sounds! The third person writes on a form what they see on the video, and the fourth records the position of the start and end of the tow and each still photo.  Each video tow is 500m long, which takes about half an hour.  The scientific staff  work in shifts of 12 hours on, 12 hours off during video work, so the work continues 24 hours a day.

Selecting video tow sites

Camera clicking on a video tow



We’ve completed 10 video tows today on the south side of Wyville Thomson Ridge, at different depths from 400m down to 800-900m, in some areas where we know trawling has been carried out in the past, and areas where trawling has not been carried out.

Trick or treat on the high seas

Halloween marks the continuation of sidescan sonar work in a south-western strip of the Wyville-Thomson Ridge. In keeping with the date, we were certainly in for some tricks and treats...

As we headed into greater water depths, it became evident that there were signs of fishing pressure on what appeared to be softer sediment communities, though unfortunately our time investigating these depths was cut short with the loss of the tow fish device fins…AGAIN!


However, the equipment downtime did attract some attention from some neighbouring critters. Bobbing around we began to see large numbers of seabirds settling on the water; suddenly, a dark fin shape and back appear from the water and as if from nowhere we were greeted with pilot whales some 70ft away from the ship.

Pilot Whales

After some whale watching it was back down below deck to prepare for the last few tows of side scan in our current location, and to start developing plans for camera work to investigate and identify the kinds of animals you find at different depths on the Wyville-Thomson Ridge.

Sidescan data processing

Sidescan sidescan everywhere but not a drop to drink

With the weather remaining thankfully calm, the sidescan sonar work continues in strips south west of the ridge. We have been lucky enough to find ourselves in the eye of a storm that we were originally expecting to hit us and continue the uncomfortably high sea state we experienced at the start of the survey.

Eye of the storm

The current calm seas over Wyville-Thomson ridge have allowed us to both recover from seasickness and continue the sidescan sonar work around the clock to get a large area surveyed, with only a short stop to reattach the tow fish fins again (and again). We have now started to plan where to place further video work in order to groundtruth selected areas.

In other news, a week in and we have now exhausted what remained on the Sky TV box, resorting to such classics as ‘Fish tank kings’, and have all become keen ornithologists seeing fulmars, kittiwakes, gannets, Manx shearwaters, black-backed gulls, and a cheeky waxwing on his last legs/wings.

Feathery offerings

We are now also preparing for a high-seas Halloween. Join us tomorrow for our next ghoulish tale!

Sidescan a go-go!

A (fairly) promising weather window provided us with the opportunity to deploy the side-scan sonar; a piece of equipment that is used to identify seabed features, such as iceberg ploughmark zones.

After some promising test runs of the sidescan sonar, we set out to build up a picture of seabed features heading down the southern slope of Wyville-Thomson Ridge between approximately 400 and 650m. The resulting sidescan sonar image revealed some fairly extensive areas of iceberg ploughmarks, ridges, furrows and rises between 400 and 550m, and what appeared to be finer sediments in the deeper depths.

After one successful tow of the sidescan sonar, the fin of the tow fish became loose and fell off, this resulted in a nail biting 120 degrees swing of the device in the water column! However, after recovering the sidescan sonar back on deck, the fins were quickly replaced and secured.

The plan going forward is to process the raw sidescan sonar data that has been collected, and to use this processed data to help select the locations where we will undertake video and camera tows.

Charlotte undertaking coordinate conversions

Side scan sonar feed from the Wyville-Thomson Ridge showing iceberg ploughmarks

Rainy deployment of the side-scan sonar