Surveying Scotland's seas 

Pobie Bank Reef in the spotlight

 

In late August, JNCC staff joined colleagues from Marine Scotland Science aboard the MRV Scotia for a two week survey of the Pobie Bank Reef candidate Special Area of Conservation (cSAC). Located approximately 20km east of Shetland, Pobie Bank Reef is made up of stony and bedrock reef, surrounded by a mixture of sediments. The aim of the survey was to gather evidence to improve understanding of seabed character and the distribution of benthic communities within the site. As fishing for seabed species currently occurs in certain areas of the site, further understanding of the sensitivity will facilitate future fisheries management.

 

Reaching 70km in length and 21km wide, the cSAC covers a large area which was divided up into four priority blocks to focus the data collection.  The survey team began by collecting acoustic data, using sidescan sonar and a multibeam echosounder to build up a picture of the type of seabed habitats present. The data collected enabled the identification of rock formations, different sediment types and even underwater pipelines on the seabed.A ling (Molva molva) following the camera plumb line © JNCC_MSS

 

Following processing by colleagues from the British Geological Survey, the acoustic data was used to help identify areas of potential rocky or stony reef, where the ground-truthing work could be focused. Ground-truthing involves towing a camera just above the seafloor, to film and photograph the seabed and build up a picture of the species and habitats present. Watching the live feed from the video the team saw a number of species including sponges, cup corals, anemones, and several species of fish - a ling followed the camera plum line for several metres! They could also see how the seabed habitats changed from boulders and bedrock, to areas of sandy sediment.  Depth also influenced the communities found on the seabed; pink coralline algae were found in shallower areas where light levels were higher, whereas sponge communities were found at deeper sites.

 

Where sediment was found, the team were able to collect samples from the seafloor using a hamon or day grab.  The samples will be analysed in a laboratory to determine exactly what type of sediment was in the sample and also to identify any burrowing animals that may be present.

 

After two weeks at sea, the Scotia was welcomed back into Aberdeen harbour in the evening of 6 September. Once the data collected has been analysed, it will be passed on to the SAC Management Advice team who are leading JNCC’s advice to Government on management measures for offshore SACs.

 

Contact File

 

Lindis Bergland

Marine Support Officer

Tel: +44 (0) 1733 866914