Habitat point records from 1989 UMBSM south Argyll and west Kintyre sealochs survey

Six mainland lochs south of Oban were surveyed during 1989 as part of the survey of Scottish sealochs. Loch Feochan, the most northerly, opens into the Firth of Lorne and is protected from the west by Mull, but has a broad exposure gradient. It lies in a lava plateau and is fiordic with two shallow sills and deep basins. The remaining five lochs, Melfort, Craignish, Crinan, Caolisport and West Loch Tarbert, are situated on the Sound of Jura in an area of Dalradian rocks and are sheltered by the Jura-Islay chain of islands. They are all oriented NE-SW apart from Loch Crinan which faces NW. Loch Craiginish is the most complex, with two sheltered lateral arms and five sills. The main body of the loch is filled with shallow sediments but there are depths of 100m at the entrance in an area of strong tidal streams. Loch Crinan shares this entrance but has no sill; it is shallow with a steep bank at its entrance and estuarine sediments at the head. Loch Melfort has a limited exposure gradient, one sill, a basin reaching 73m and depths of 30-40m throughout. West Loch Tarbert has a single sill but is predominantly shallower than 10 m. Loch Caolisport, with no sill, is moderately exposed at its head. Tidal ranges in West Loch Tarbert are amongst the smallest in the British Isles whilst those in Loch Feochan are more typical of the Scottish west coast; strong tidal streams running through the complex of offshore islands are one of the dominating features of the region. The area as a whole has a limited exposure gradient with nowhere more than moderately exposed, a limited range of sublittoral sediments and a moderate range of rocky substrata. There is a considerable amount of boat traffic through the Crinan Canal and yachting is an important activity. All of the lochs apart from Crinan have salmon and shellfish farms but there is no other industry. There are two MCA's, one pMNR (Loch Sween) and several SSSIs in the area. Much littoral work has been carried out in the area, most noticably by Lewis (1957) and Lewis and Powell (1960a,b) but there have been few sublittoral studies. Sixty-two sites were surveyed of which 4 were littoral and 58 were sublittoral; 26 habitat/community types were described. Infralittoral bedrock communities ranged from rich Laminaria hyperborea forests in the tide exposed areas, through mixed forests of L.hyperborea and Laminaria saccharina to L.saccharina and Chorda filum in the most sheltered regions. Sheltered circalittoral rock in upper Loch Feochan supported the anemone Edwardsiella carnea where as in Loch Melfort brittlestar aggregations dominated the rock surfaces and reduced the diversity. This was the only loch where Protanthea simplex was found. Excellent examples of tide-swept rock communities were present in the Craignidh-Crinan area, supporting a great variety of species including Swiftia pallida, sponges, ascidians, brachiopods and echinoderms. Several communities were represented in a small area and an unusually large number of interesting species were found. The sills in Loch Feochan and West Loch Tarbert also supported diverse communities exposed to tidal streams. Sediments were less varied and were primarily muddy. Three main community variants were described, these being dominated by Virgularia mirabilis, Cerianthus lloydii and burrowing brittle stars. Coarser, moderately exposed sediments held a wide range of algal species. Deep soft mud inhabited by Nephrops norvegicus was found in Loch Melfort, but Funiculina quadrangularis, often found in similar habitats, was not recorded. Shallow muds in the heads of the lochs supported Philine aperta; this habitat extended over 9km in West Loch Tarbert. Seven habitat/community types and twenty-three species have been provisionally assessed to be of Regional or International importance. Records currently considered sensitive have been removed from this dataset.

Organization: Joint Nature Conservation Committee