Survey to determine the scale of the subtidal seagrass resource present along the north-west coast of Scotland (within the SNH North Highland area). The results of work will support the on-going delivery of SNHâs statutory marine nature conservation remit.
The study area extends from Greenstone Point in Gruinard Bay to Sheigra near Kinlochbervie. Predominantly rocky, rugged coastline interspersed with large embayments, sealochs and scattered small islands. Open outer coast is exposed to considerable wave action, sealochs are protected by sills or narrows and are very sheltered.
A series of 28 areas were targetted during the survey.
- Bathyscope (Glass-bottomed bucket) was used for rapid assessment of presence of seagrass in clear shallow waters (~4-5m max.) where visability was such that a rapid assessment of benthic habitats could be made over the side of the survey vessel.
- Drop-down video equipment was used in water depths greater than 5m or where sea conditions precluded the use of a bathyscope. A total of 56 separate drop-down video drops/ short tows were taken of between 1-3 minutes duration. Footage was recorded onto miniDV tapes. Field notes detailing site number, position, depth, time and conspicuous habitat features were taken for all drop-video sampling sites on standardised recording forms. Video footage was logged. Video footage was analysed using freeze-frame, slow motion and standard play speed to identify as many conspicuous species as possible and a determination of broad substrate type. Species abundance was measured to SACFOR or percentage cover where practicable. Species determination referenced Howson and Picton (1997). Records were tagged with biotopes with reference to MNCR biotope classification version 04.05 for subtidal sediments an infralittoral rock (97.06 version for other habitats).
- Still photography was an integral part of the survey and surface digital photographs were taken throughout. A small number of sublittoral habitat shots were taken whilst snorkelling. Photography was logged. Two still images were also extracted from each sample site.
- Snorkelling was undertaken where vessel access was restricted.
Positional information was recorded from dGPS in the field as British National Grid format (OSGB36 datum) and validated against downloaded Latitude and Longitude coordiante pairs (WGS84 datum).
The data is structured into 4 Events and 56 Samples