Fauna and flora associated with moderate tidal conditions

The greatest variety of fauna and flora is found in areas exposed to moderate tidal conditions. These communities include species normally characteristic of deeper water, such as the sponges Mycale lingua and Clathria barleei, and the feather star Leptometra celtica. There are other species considered scarce, including the brown alga Desmarestia dresnayi, and several living at their geographical limits of distribution. These include the southern cup coral Caryophyllia inornata, the nationally scarce brittle star Ophiopsila annulosa and the northern bryozoans Bugula purpurotincta and Caberea ellisii. Of particular interest is the rarely recorded sea fan Swiftia pallida, which is unusually widespread in the Firth of Lorn area. Associated with S. pallida is the sea fan anemone Amphianthus dohrnii. The rare anemone Arachnanthus sarsii has also been recorded in the area.

Fauna and flora associated with strong tidal conditions

Communities characteristic of strong tidal streams are found in the sounds. Of particular note is Clachan Sound, a tide-swept and wave-sheltered channel with littoral boulders and bedrock supporting a variety of brown seaweeds including a number of wracks and laminarians (kelps) and a rich associated fauna.

In the strongest tidal streams communities are restricted to crevices and areas in the lee of the tide. In the Gulf of Corryvreckan, open rock is dominated by the oaten pipe hydroid Tubularia indivisa and the barnacles Chirona crenatus and Balanus hameri, species indicative of a highly scoured environment. Also of note in these relatively deep, tide-swept areas is the presence of species normally considered characteristic of shallow surge gullies, such as the gooseberry sea-squirt Dendrodoa grossularia and the lace sponge Clathrina coriacea, and species typical of much more wave exposed, open coast sites, such as the jewel anemone Corynactis viridis and the northern starfish, Leptasterias muelleri.

The site contains a greater variety of diverse communities than any area of comparable size in the west of Scotland.