In October 2008, Fisheries Research Services (Aberdeen) collected video and photographic stills imagery from 61 stations in the Pentland Firth and Orkney Islands. This formed part of a wider marine survey programme requested by Scottish Government, to inform potential marine renewables development in this region. This report provides a description of the seabed habitats, species assemblages and biotopes evident from the video and stills footage along with a preliminary assessment of their conservation importance and potential sensitivity to renewable energy schemes in the area.
- Most sites examined in the Pentland Firth displayed low diversity circalittoral tideswept rocky communities, dominated by a sessile fauna of Balanus crenatus and Urticina felina, with an area of coarse, and apparently impoverished, sediment in the southwest of the Firth. Elsewhere, the habitats were predominantly sandy, sand-scoured rock or mixed substrates of sand and stones, which the visual evidence suggested supported low diversity communities. A total of 14 biotopes were recorded.
- The Pentland Firth probably represents the most extensive example of the UK BAP Priority Habitat “tidal rapids” in the United Kingdom. However, the communities observed during this survey were of low diversity, and composed of very common, widely distributed, scour-tolerant species, likely to be tolerant to modest reductions in current speed or sediment disturbance caused by the introduction of energy schemes. Similarly, the likely impact of schemes on other habitats recorded during the survey is considered to be unlikely to significantly affect the conservation of biotopes, considered to be of conservation importance, at Scottish or UK levels.
- Three 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.
- Regarding commercially important species, the sites surveyed in the Pentland Firth were found to support a large population of small Cancer pagurus, and so the implications of developments for a possibly important nursery ground for this species may need to be considered.