Seagrass Beds - Intertidal sediments and Inshore and shelf subtidal sediments

These layers cover:

Intertidal sediments:

1. Beds of the dwarf eelgrass Zostera noltii are found on the mid and upper shore in muddy sand or sandy mud on wave-sheltered coasts. This habitat is sparsely distributed around Scotland but is present at various sites in the Moray Firth, Firth of Tay, Shetland and the west coast and Western Isles.

Scotland has about 20% of the north-west European beds and the Cromarty Firth supports the largest bed known in the UK. The eelgrass roots serve to stabilise and bind the underlying sediment and support a community of polychaete worms, mud shrimps, mud snails, shore crabs and bivalves including the edible cockle (Cerastoderma edule).

2. This layer shows the distribution of intertidal (littoral) seagrass bed habitats which cannot be categorised into the other layers.

Inshore and Shelf Subtidal Sediments:

3. Subtidal seagrass beds of the eelgrass Zostera marina are considered nationally scarce and found on the west coast of Scotland extending up to the Northern Isles with a few records from the east coast in more sheltered bays and firths. The eelgrass stabilises the underlying sediment and absorbs a proportion of the wave energy as well as being a nursery area for many commercially important species of fish.  Scotland holds about 20% of the seagrass beds in North-west Europe with many being considered degraded following significant declines.

4. Ruppia maritima grows in soft sediments in sheltered shallow coastal waters, from full salinity to nearly fresh water but mainly in brackish waters of lagoonal habitats, lochs, estuaries, creeks and pools in salt marshes, wetlands, ditches and lakes. Found on the west coast, the Outer Hebrides, Orkney, Shetland and, intertidally in the Cromarty Firth.

5. This layer shows the distribution of subtidal seagrass beds which cannot be categorised into the other layers.