Marine Special Areas of Conservation

Marine Features of Conservation Interest

Within the Western Isle the current list of marine features of conservation interest, as per the EC Habitas Directive include:

• Lagoons
• Large shallow inlets and bays
• Reefs
• Submerged or partially submerged sea caves
• Grey seals

Lagoons

Lagoons are areas of shallow, coastal salt water, wholly or partially separated from the sea by sandbanks, shingle or, less frequently, rocks. The salinity in lagoons can vary from nearly fresh to hypersaline and generally they have restricted tidal movements.

Lagoons are the only marine habitat in the UK to be listed as a priority habitat, meaning they are of special significance within a European context and therefore in need of special management measures.

Sites selected for this feature within the Western Isles include:

Loch nam Madadh,
Loch Roag
Obain Loch Euphoirt

Large shallow inlets and bays

Large shallow inlets and bays are large indentations of the coast, generally more sheltered from wave action than the open coast. They are relatively shallow, usually averaging less than 30m in depth. Within the Western Isles the physiographic type of large shallow inlet and bay encountered is the fjard, which can be described as a series of basins connected to the sea via shallow and often intertidal sills. Fjards are found in areas of low-lying ground
which have been subject to glacial roughening. The have a highly irregular outline, no main channel and lack the high relief and U-shaped cross-section of fjordic inlets.

Sites selected for this feature within the Western Isles include:

Loch nam Madadh

Reefs

Reefs are rocky marine habitats or biological concretions that rise from the sea bed. They are generally subtidal but may extend as an unbroken transition to the intertidal zone, where they are exposed to the air at low tide. Two main types of reef can be recognised, those where the structure is created by the animals themselves (biogenic) and those where animal and plant communities grow on raised or protruding rock (rocky reefs). The Western Isle support a range of rocky reefs.

Sites selected for this feature within the Western Isles include:

St Kilda

Submerged or partially submerged sea caves

Cave communities vary considerably depending on the structure and extent of the cave system, their degree of submergence and exposure to scour and surge, and the nature of their geology. Caves can vary in size, from only a few meters to more extensive systems, which may extend hundreds of meters into the rock. There may be tunnels or caverns with one or more entrance, in which vertical and overhanging rock faces provide the principle marine habitat. Caves are typically colonised by encrusting animal species but may also support shade-tolerant algae near their entrances.

Sites selected for this feature within the Western Isles include:

St Kilda

Grey seals

Site selection for grey seal Special Areas of Conservation takes account of the UK’s responsibility to protect the population of this species. The largest breeding colonies have been selected, based on pup production. Sites were selected using the most up-to-date population information available at the time, although populations at individual sites may fluctuate. Colonies have also been selected to ensure coverage of the geographical range of breeding in the UK. The sites recommended for selection contain a significant proportionof the UK breeding population of the grey seals.

Sites selected for this feature within the Western Isles include:

Monach Islands
North Rona.