Wednesday, 20 March 2013

Of Tows and Grabs

Yesterday marked the beginning of our groundtruthing campaign here at Wight Barfleur Reef cSAC. Groundtruthing means taking a sample of the seabed to enable us to see which habitats and species are below us. This can be used with the acoustic data we collect from the multibeam and sonar systems to make habitat maps, which in turn are used to inform management decisions for areas of conservation importance. Having accurate maps is important, as we can only protect species and habitats that we know about! We used two techniques yesterday to sample the seabed. The first of these is the "Drop Camera". As it's name suggests, this is a camera we drop over the side of the Endeavour. The camera is mounted on a frame, which houses lights and other equipment, and also protects the camera from any "bumps". This unit is then lowered to just above the seabed, and we tow it for about 10 minutes, recording video footage and taking pictures. So far we've seen Annex I stony and bedrock reef, habitats named after the Annex of the EC Habitats Directive in which they appear. We have also seen gravels and sands, as well as some starfish, sunstars, fish, crabs, mussels and lots of impressive sponges, bryozoans and anemones.  

Flustra foliacea (bryozoan- beige with erect fronds) and Hemimycale columella (encrusting sponge- also beige, to right) on current swept circalittoral rock

Pachymatisma johnstonia (Elephants ear sponge- white), an axinellid sponge (yellow) and Tubularia indivisa (Hydroid sps- green) on current swept circalittoral rock
Recovering the Hamon Grab (Photo Neil Golding, JNCC)
The second groundtruthing tool we've used is the "Hamon Grab". This is also dropped over the side of the ship (though, like the camera, remains attached to the boat by a cable and wire!). When the Hamon Grab reaches the seabed it scoops up a small sample of sediment. This is then hauled back up to the ship, where excited scientists wait to see what is contained in the sample. As Wight Barfleur is quite rocky, we have been using the Drop Camera more than the Hamon Grab, though this is set to change at Bassurelle Sandbank cSAC.
Excited Scientists! (Photo Bill Meadows, Cefas)

Above the water, we've also come across some of Her Majesty's finest. So far we've been flirted with by an RN Lynx helicopter and warship, as well as a Border Agency launch. However, pictures remain classified...

For now, we will continue to gather evidence at Wight Barfleur, and will let you know what we find!