Inshore and Shelf Subtidal Sediments

Inshore subtidal sediments include shingle, gravel, sand and mud extending to the depth at which there is no effect from waves, typically around 50-70m. The shelf sediments extend to around 200m depth. Inshore subtidal sediments also include lagoons and maerl, a red seaweed with a hard chalky skeleton that forms small twig-like nodules which accumulate to form loosely interlocking beds, creating the ideal habitat for a diverse community of organisms.

Inshore subtidal and shelf sediments cover an extensive area of the sea bed. The east coast of Scotland in general has a relatively narrow fringe of largely sandy sediments with mud in the inner firths but there are more extensive areas of sand and mixed sediments in the Moray Firth and around the Orkney Islands. There is an extensive area of shallow sand in the south-west of Scotland off the coast of Dumfries and Galloway, whilst much of the sea bed in the Minches and many of the west coast sea lochs is of mud. These differences are the result of differences in depth, wave exposure and tidal currents with the mud habitats occurring in the deeper more sheltered areas. Much of the sea bed out to the continental shelf break comprises subtidal sediment.