Habitat point records from 1988 MNCR Lochs Duich, Long and Alsh survey

Lochs Duich, Long and Alsh lie on the Scottish west coast, to the east of Skye. They were surveyed in 1988 as part of a major survey of Scottish sealochs. Loch Duich is a long narrow loch with sides steeply shelving to form a basin over 100 m deep. Loch Long comprises two basins over 30 m deep, seperated by a shallow narrows, and opens, together with Loch Duich, into Loch Alsh which has a main deep basin and more complex shallower basins. Loch Alsh opens to the Sound of Sleat and to the open coast via deeper narrows which are subject to very strong tidal streams. Strong tidal currents are also present in Loch Long narrows and the mouth of Loch Duich. The lochs are sheltered or very sheltered from wave action. Loch Duich and Loch Long have a high freshwater input and Loch Long is Scotland's second most brackish sealoch. The shores are predominantly rocky, mostly metamorphic gneisses and schists. with only small embayments of sediment. Bedrock, including cliffs to beyond 50 m, and boulders occur extensively throughout the sublittoral zone, extending to predominantly muddy sediments. The area is relatively undeveloped and there is little pressure from fishing or fish farming. Eleven littoral and 41 sublittoral sites were surveyed, from which nine littoral and 21 sublittoral communities are described. The shores were dominated by fucoid algae throughout, excepting on more steeply sloping barnacle dominated bedrock. Freshwater runoff and extreme wave shelter produced beds of mussels and detached knotted wrack Ascophyllum nodosum var. mackaii. Fucoid shores gave way to a forest of the kelps Laminaria saccharina or, where there was increased water movement, Laminaria hyperborea. Circalittoral rock was characterised by the anemone Protanthea simplex and the brachipods Neocrania anomala and Terebratulina retusa, with the squat lobster Munida rugosa typical of boulder and cobble plains. Beds of the horse mussel Modiolus modiolus, maerl and brittle stars were present in tidally swept areas. The seapen Virgularia mirabilis and burrowing brittle stars Amphiura spp. were ubiquitous in the muddy sediments, together with populations of the seapen Funiculina quadrangularis, burrowing megafauna, the opisthobranch Philine aperta, the gastropod Turritella communis and the anemone Pachycerianthus multiplicatus, depending on the nature of the sediment. Shallow sediments supported a Laminaria saccharina/Chorda fillum association or mats of filamentous algae. The three lochs supported a wide range of communities typical of sheltered sealochs, including well developed examples of communities on extremely sheltered shores, deep sublittoral bedrock and in deep soft sediments. In addition unusual communities resulting from brackish water influences, atypical variants on widespread communities (Ophiopholis aculeata brittle star beds) and large populations of uncommon species (Limaria hians, Pachycerianthus multiplicatus) combined to provide high biological interest. Eight communities and eight species have been provisionally assessed to be of regional, national or international conservation importance. Records currently considered sensitive have been removed from this dataset.

Organization: Joint Nature Conservation Committee