Habitat point records from 1990 MNCR Loch Leven (Lochaber) survey

Loch Leven is a relatively small sealoch in Lochaber District of Highland Region on the west coast of Scotland and forms part of the extensive Loch Linnhe system. To the north lies Fort William, one of the principle west coast towns. At the head of the loch lies Kinlochleven, a town established in 1909 when the British Aluminium Company (now British Alcan) built a large smelter there. British Alcan have a consent to discharge spent turbine water into the River Leven although this is unlikely to influence marine communities in the loch. Loch Leven is set amongst some of the most spectacular mountain scenery of Scotland and the Glen Coe range is immediately south-east of the loch. Loch Leven has been investigated by staff from the Scottish Marine Biological Association although little published marine biological information is available for Loch Leven. Loch Leven is subdivided into a series of basins by shallow sills. Two of these sills coincide with a narrowing of the loch at Ballachulish Bridge and Caolas nan Con forming tidal rapids systems. Littoral zones within the loch are predominantly rocky with only a few areas of sediment. These rocky habitats extend into the shallow sublittoral and then give way to sediment in deeper water. Loch Leven has a large freshwater input with a distinct halocline present throughout the loch, at least during high river flow. The consequent salinity reduction appears to have a marked effect on communities within the loch. Te area was surveyed in April 1990 as part of the Marine Science Branch field training week. A total of 12 littoral and 26 sublittoral sites (including four dredge sites) were surveyed, which generated 62 littoral habitat records and 47 sublittoral habitat records. From these records, six littoral and 47 sublittoral habitat/community types have been identified. In general, species richness was low in comparison to similar habitats from other sealochs. Rocky shores were characterised by fucoid algae. To the east of Caolas nan Con, salinity was variable to low and eulittoral zones were characterised by the brackish water alga Fucus ceranoides. Species richness in the sublittoral habitats declined with increasing distance east away from the mouth of the loch, probably a reflection of the decline in salinity. Sublittoral substrata throughout the loch were primarily sedimentary with muddy sand in the outer basin, muddy gravel in the deepest part of the central basin, and mud and soft mud in the eastern arm of the loch. Sedimentary communities were characterised by polychaete worms, bivalve molluscs and brittlestars. Around the mouth of the loch, shallow sublittoral substrata were primarily bedrock and boulders on sediment with Laminaria saccharina kelp forest with sparse red algae beneath; algal diversity declined with increasing distance east. Circalittoral hard substrata were boulders and cobbles on sediment; Modiolus modiolus beds were present where tidal flow was higher. The marine conservation interest of the area has been assessed and three communities and three species were considered to have notable marine conservation interest. Within the upper loch basin, extremely sheltered open rocky shores with Fucus ceranoides was considered to be of regional conservation importance. Ascophyllum nodosum ecad mackaii beds and circalittoral bedrock and boulders on sediment with Psolus phantapus communities were considered to be of local conservation importance. Records currently considered sensitive have been removed from this dataset.

Organization: Joint Nature Conservation Committee