The seabed habitats, species assemblages and biotopes at 22 sites off the west coast of Orkney and in the Pentland Firth were described from video footage collected in 2009 by Marine Scotland Science), Aberdeen. The aim was to aid Scottish Natural Heritage (SNH) in providing a preliminary assessment of the conservation importance of benthic species and habitats in relation to the development of renewable energy schemes in the area.
- Seven circalittoral biotypes were recorded at the 19 sites off the west coast comprising either fairly low diversity faunal crust communities on rock (supplemented in places with dense brittlestars) or clean sands and gravels, with scattered stones supporting a low diversity epifauna off Hoy. Two circalittoral biotypes were recorded at three tideswept sites in the Pentland Firth. To the west of Stroma the seabed has formed into waves of shelly sand with little evidence of biota. To the east of Stroma and to the south of South Ronaldsay scoured rock supports a low diversity community, dominated by Urticina felina and patches of erect bryozoans and hyroids.
- Two species of recognised conservation importance were recorded but it is considered that conservation of these species is unlikely to be adversely impacted by renewable energy developments in the surveyed area. The sandeel, Ammodytes marinus, also appears to be present and so the implications of energy schemes for this species will need to be considered. Assessment of the conservation importance of the infaunal community of the sedimentary habitats must await the results of infaunal sampling.
- Four of the biotypes recorded during the survey have been recognised as being of conservation importance. Three of these biotypes may be of local significance in terms of their possible role as sandeel habitats. The fourth biotype, tideswept reef, supports a low diversity community in the Pentland Firth as a result of high current speeds combined with high scour. As a poor example of its type, it is considered to be locally of low conservation importance and probably of relatively low sensitivity to physical changes resulting from the establishment of renewable energy schemes.