Monday 29 October 2012

Weekend break for the ridge

After a rocky nights sleep we eventually made it to the Wyville Thomson Ridge at 01:00 hours on 27th October 2012. With relatively calm weather at dawn, calibration and testing of the on board kit began. This included lowering of the camera frame onto the ridge and testing the lasers and lights. A Sound Velocity Profiler was then lowered through the water column to find out the speed of sound at different water depths. This is very important to help us when calibrating the mutibeam system – a piece of kit that produces a depth image of the seabed and enables us to then pick out features of interest such as pinnacles and furrows.

Blowing a gale

With the forecast not looking particularly encouraging over the next few days, we have decided to focus on using multibeam to generate a picture of the seafloor bathymetry in the northern part of the Wyville Thomson Ridge study site on a relatively shallow part of the ridge at c350m. This is in the hope that there will also be time to get some video and camera tows included in the same area before the bad weather arrives.

The majority of Saturday and the early hours of Sunday morning were spent multibeaming the shallow part of the ridge feature. Despite the fairly rough sea conditions, the pictures on screen were of reasonable enough quality and resolution to help guide the decision on which areas might be of interest to collect data using towed video and camera transects.

Initial multibeam outputs

Using multibeam outputs to select areas for towed video transects

At 08:00 hours on 28th October we deployed our first towed video transect. Attached to the frame was a HD camera, supplied and run by Plymouth University PhD student Rebecca Ross. This was the camera’s first outing and is already starting to produce results.

In five hours we had three transect lines worth of data, but the bad weather came creeping back halting any further progress today. Fingers crossed for another weather break soon!

Deployment of towed video camera

High definition camera frame image from Plymouth university with size calibration lasers   

Munida rugosa (Squat lobster) on stony reef at Wyville Thompson Ridge

Cidaris cidaris (Pencil urchin) on stony reef at Wyville Thompson Ridge

All hands on deck and bon voyage

Progress so far has been slow, with the acoustic equipment requiring some final checks before departure. Once we finally left the harbour at 14:30 hours on 25th October 2012 it was a frantic wave to our colleagues in the JNCC Aberdeen office before steaming on to our first destination – The Southern Trench. The intention was to test and calibrate some of our on board kit, but unfortunately due to the Force 8 winds and big sea swell, we haven’t managed to do any calibration yet.

MRV Scotia

Then weather conditions took a turn for the worse and it wasn’t long before many of the staff on board were turning a little green. A tour of the ships facilities and getting to know the ins and outs of the sampling equipment has kept us all busy so far. We are due to arrive at the first of our study sites the Wyville-Thomson Ridge at 10pm on 26th October 2012. Fingers crossed for good weather!

Trying on an immersion suit

Thursday 25 October 2012

MRV Scotia to survey Wyville Thomson Ridge SCI

Four members of JNCC staff have joined the Marine Scotland research vessel ‘MRV Scotia’ for the next two weeks to undertake a detailed survey of the Wyville Thomson Ridge candidate Special Area of Conservation. The Wyville Thomson Ridge is a rock ridge situated in the Atlantic Ocean at the northern end of the Rockall Trough approximately 150km north-west of Cape Wrath, Scotland. The site was submitted to the European Commission in 2010 for its reef features and has since been made a Site of Community Importance (SCI).

Wyville Thomson Ridge  © Crown Copyright

Wyville Thomson Ridge rises from 1000m at its deepest point to 400m at the summit. Along the ridge there are large areas of stony reef, thought to have been formed by the ploughing movement of icebergs through the seabed at the end of the last ice age. Bedrock reef is present on the flanks of the ridge and, due to the differences in water masses, there are different species compositions on either side.These reef communities comprise sea urchins, sea spiders, sea cucumbers, dense beds of featherstars and brittlestars, a range of colourful sponges and both cup and soft corals.

The main aim of this survey is to obtain evidence to facilitate fisheries management discussions in relation to Wyville Thomson Ridge SCI.  In addition, the survey provides an opportunity to improve our understanding of habitat distribution and community composition within the site and develop methods for future site monitoring.

After surveying Wyville Thomson Ridge, the vessel will transit to an area near the Faroe-Shetland Channel to investigate the extent of deep-sea sponge aggregations for the Scottish Marine Protected Area Project.