Isle of Man Sublittoral Survey I (1994 - 97)
The
Isle of Man has an interesting and diverse coastline, ranging from spectacular
seacliffs to low lying sedimentary beaches. The underwater scenery is similarly
diverse and a number of sublittoral habitats of potential conservation interest
have previously been recorded, such as maerl, seagrass and mussel beds
(including beds of the horse mussel, Modiolus
modiolus), and the tide swept waters around the Calf of Man
(Geffen et
al., 1990, Morrow et al., 1993)
.
Despite
the presence of these habitats and several species which are otherwise rare in
UK waters, detailed, broad-scale description of the sublittoral habitats around
the Isle of Man has not been made. Therefore, it was decided to conduct a Phase
I (habitat description) survey around the entire coastline of the Island, using
volunteer divers, supported by the local knowledge and expertise of staff at the
University of Liverpool’s Marine Laboratory at Port Erin. In addition, the
survey provided an opportunity for amateur divers to participate in a practical
conservation project.
Funding
was sought from local businesses, and received from Manx Airlines Project 2000
environmental awards scheme, with an additional sum in the final year from the
Manx Nature Conservation Trust. Dive record forms were based on those used by
the UK Joint Nature Conservation Committee (JNCC). The emphasis was very much on
the collection of habitat data, making the survey possible to divers with little
or no biological knowledge.
One
hundred and sixty two surveys were conducted by 63 divers. These were entered in
to a Microsoft Access database, facilitating analysis, and providing a useful
source of baseline information against which any future environmental change
could be assessed. Additionally, sites of potential conservation interest were
identified and are proposed for subsequent Phase II (species) surveys.
Generally,
bedrock and boulder slopes dominate the habitats close to the shore in the south
of the Island, with sand and gravel sediments at greater depths. The sedimentary
coastline of the north of the Island slopes down to seabeds of a similar
composition. Sediment is generally finer on the west coast than the east coast,
reflecting the deeper water closer to shore at the former.
Features
of potential conservation interest were identified where Phase II surveys should
be conducted by experienced marine biologists. These include extensive areas of
maerl and a sublittoral bed of the edible mussel, Mytilus edulis, both located around the Point of Ayre, and the sea
caves of the Meayll Peninsula. Additionally, a previously undescribed seagrass
bed in Ramsey Bay should be mapped.