Marine biological survey to establish the distribution and status of ...

the morning of the 28 th September. David Bova from Marine Scotland Science (MSS) joined
the survey on Canna for a few days to operate the SNH / MSS Seaeye Falcon ROV. One
day was spent grab sampling and one day was given to the ROV; the remainder of the time
was spent using the UMBSM drop-down video.
2.2.2 Diver sampling
The diving fieldwork was carried out by a team of four divers from 28 th August -
4 th September 2010. Lophelia was used as the diving platform for this work. All of the
diving was carried out in accordance with the Approved Code of Practice for scientific diving
projects (Health and Safety Commission, 1998). An Enriched Air Nitrox system was
deployed for divers to use at safety stops. Slack water was only required for diving on the
outer parts of the Great Wall, on the south-east of Sanday.
The survey team travelled to Canna on the Caledonian MacBrayne ferry from Mallaig and
returned to Mallaig in Lophelia. As no vehicles can be taken onto Canna, much of the
equipment was transported on the freight van that serves the islands; diving cylinders were
carried on separately. The team stayed at the guesthouse on Canna for the first part of the
survey and moved to the hostel on Rum on the 1 st September. The SNH compressor was
used for air fills. Equipment was stored in the harbour sheds at Canna pier; microscopes
were also set up here.
2.3 Remote video sampling
2.3.1 Shallow water video survey
The shallow water video sampling locations were selected to provide an overview of the full
range of habitat types likely to be present in the nearshore area, within a maximum working
depth of approximately 35 m. Greater densities of video stations were assigned to specific
locations to determine the continued presence and extent of the following previously
recorded MPA search features:
Burrowed mud.
Kelp and seaweed communities on sublittoral sediment.
Northern sea fan and sponge communities.
Seagrass beds.
Tide-swept algal communities.
The 56 shallow water video stations sampled along the Canna and Rum coastal margins are
illustrated in Figures 6 and 7.
The ASML drop-down video equipment (Plate 2) is a light-weight system that can be handhauled
and operated from a RIB. It is based on a Sony 3CCD digital video camera (DRV
950) with mini DV format tapes and is designed to drift above the seabed rather than drag
along it in contrast to systems which utilise the sledge mode of operation. The aluminium
housing is rated to 130 m. The lights are powered by an independent surface 110 v system
(generator or vessel supplied) and so do not rely on battery power. The system is controlled
from the surface and the digital video footage can be recorded in the camera and
simultaneously relayed to the surface via the umbilical where it is viewed and recorded on a
Sony mini digital VCR. A surface control box provides remote control facilities for both the
camera and the lights.
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