This rapid survey was undertaken to supplement observations from Loch Long in Connor 1989 (CSD Report 977, MNCR Report SR/010) and particulary to investigate distribution of species on hard substrata in relation to the lowered salinity which eists along Loch Long. The flora and fauna present on hard substrata along Loch Long clearly reflects the salinity gradient. Effects of very low salinity at the head of the loch are less marked than expected with Fucus ceranoides confined to streams. The Fucus muscoides bed was very well developed. The apparently very dense population of Mya arenaria in the sand and sandy mud of the delta at the head of the loch is notable if only because extensive pure sediments areunusual in sealochs.
