As a result of the depths at which they occur, and the exposed
locations of the majority of sites, reduced salinity is rarely a significant factor.
Nevertheless reduced salinities do occur in sea lochs at depths of 30 m+ and specialised
CFT communities occur there, as they do also in some south western rias. They have been
described from Loch Etive (Howson et al., 1994), Loch Fyne, Loch Leven, Loch Long and Loch
Ewe. The community is characterised by brachiopods, calcareous tubeworms and sponges.
Reduced and variable salinity biotopes characterised by sponge-dominated communities have
also been described from Plymouth Sound and other south-western rias (Moore, 1995).