Wednesday, 16 January 2013

Grand finale

We went out with a bang on the final day of the survey, encountering a plethora of sea pens. What should the collective noun for sea pens be? …Set? …Forest? ...Bed?

As we have been very lucky with the weather, we made quick progress and had time left at the end of the main survey programme to do some extra investigations in areas of particular interest. We returned to the core area of Central Fladen site to record some additional video footage around the stations where the tall sea pen Funiculina quadrangularis had been found, in order to better estimate its distribution. The night shift struck gold at one station where a high density of tall sea pens was recorded, and they took some fantastic pictures. Tall sea pens were also found at a number of other stations either side of the area they had been identified earlier in the survey. It appears that they are distributed in a thin band along the Central Fladen site in association with slightly coarser sediment, following the contours of the bathymetry. Stations placed either side of this thin band did not reveal any further tall sea pens.

Brittlestar entwined around a Funiculina seapen

Spider crab (Lithodes maja)
During the day, we also returned to an area to the north-west of the Central Fladen site where multibeam bathymetry revealed a large trench reaching down to over 300m. There was a strong backscatter return at the bottom of this trench which indicated a coarser sediment. We collected video footage and a grab at two locations along this trench in order to groundtruth the bathymetry data and capture any variation in sediment and associated fauna as depth increased. The drop-camera was used as the camera sledge may have run into difficulties being towed down such a step decline. Scientists gathered round to see what the depths would reveal, including a few bleary-eyed members of the night shift who had stayed up especially. The video footage confirmed predictions regarding sediment, showing muddy sand with shells going down and an increasing proportion of cobbles and boulders. A grab was taken at the foot of the slope using the Hamon grab, as this is more effective than the Day grab at sampling coarser sediments. The grab retained sediment with a high proportion of gravel and fewer infauna species.

So that brought the Fladen grounds survey to a close, and we bid farewell to the Scottish seas and began our steam back to Lowestoft. We’ve had an enjoyable and productive survey all in all, successfully confirming the presence of the tall seapen and verifying the burrowed mud habitat predicted in UKSeaMap through ground truthing. Many thanks to the crew of the Endeavour and the Cefas team for a great trip.

Day shift scientists

Night shift scientists

Bridge crew

Deck crew

Signing off (with a sea pen, obviously)