Loch Maddy

Sound of Arisaig

Strangford Lough

Plymouth Sound and Estuaries

Loch Maddy is recommended as a candidate SAC by reason of the very well developed system of saline lagoons. These are predominantly shallow and mostly soft bottomed, though limited CFTs are present. However there are more extensive circalittoral rock environments in the entrance to the Loch.

To quote from the SNH recommendation: "Reefs are restricted to the littoral zone and shallow water in the shelter of the lochs, although bedrock and boulders extend to depths of around 30 m in the more exposed entrance areas."

"There is little circalittoral rock other than in the entrance areas where there are rich animal communities with species such as the sea fan Swiftia pallida and the colonial ascidian Diazona violacea present, a few sheltered boulder slopes further into the lochs with solitary ascidians such as Ascidia mentula and very sheltered shallow bedrock outcrops and boulders on soft mud in the inner basins with unusual combinations of anemones including Sagartiogeton laceratus and Cereus pedunculatus and algae. Particularly unusual are communities of very tall laminarians with diverse epiphytes, including large colonies of the sponges Grantia compressa and Halichondria panicea, and an abundance of ascidians, particularly Ascidiella scabra, and the feather star Antedon bifida on scoured shallow bedrock in inner Loch Maddy. These are the most extensive and best developed examples of such communities known in Scotland."

"The boundary encloses the entire marine part of the Loch Maddy system, with the eastern boundary running from Weaver's Point on the northern side of the entrance to Rubha nam Pl`eac on the southern side. This includes examples of the moderately exposed bedrock communities of the entrance area which are a feature of sealoch entrances on the east of the Hebrides."

Thus Loch Maddy does contain a variety of CFT biotopes in the entrance to the Loch, including some which are regionally rare, though they are not a criterion for its selection. Descriptions of the subtidal communities are found in Dipper & Mitchell (1980), Howson (1991) and Howson et al. (1994).

To quote the SNH recommendation: "Sound of Arisaig has an unusually high diversity of sublittoral sediment habitats within a relatively small area. The extensive sublittoral maerl beds are the richest known in Scotland whilst the site also has a range of representative marine and brackish sediment habitats and associated communities".

Hence the justification for candidate status is based entirely on the interest of the soft sediments within Lochs Ailort, Ceann Traigh and Moidart. However the proposed boundaries of the SAC include a considerable area of the Sound of Arisaig, and the predominantly rocky coastline from Rubha Aird Druimnich northwards to Rubha Chaoliai.

"The region is characterised by a broken rocky coastline and clear high salinity water and has a boreal fauna and flora. The recommended site has an excellent combination of very sheltered inlets and exposed open coastline with considerable diversity of sediment habitats, high species richness and communities which reflect the major features of the region. The species complement illustrates the transition from southern to northern influences along this coastline with species with both predominantly southern and predominantly northern distributions found."

So whilst not selected on their account, CFT biotopes occur within the boundaries of the SAC, and may be of interest because of their biogeographic position. Descriptions occur in Howson (1990), and Howson et al. (1994).

Strangford Lough has been selected as a SAC site because of its Annex I feature of shallow inlets and bays. However, the Lough is an extremely diverse ecosystem (Brown, 1990). Large areas are indeed shallow soft bottom environments, but there are also substantial areas of mussel (Modiolus) beds of considerable conservation interest. In the narrow entrance to the Lough tidal currents reach an excess of 8 knots, there are depths in excess of 50m, and the substratum is predominantly rock. This area supports a range of extremely interesting CFT biotopes which are not elsewhere available in this biogeographical area. They should be regarded as an important constituent of the SAC.

A detailed report of the subtidal environment in Strangford Lough is contained in Erwin et al. (1986). The 'narrows' leading into the Lough are indicated as sites of both upper and lower circalittoral areas with >20% bedrock (loc. cit. Maps 23 & 24), and of 50-100% bedrock at 20-50 metres (Map 39). The report contains considerable detail regarding sites surveyed and species found.

The reasons for selecting this area as a candidate SAC were the Annex I habitats - sandbanks, estuaries, and inlets and bays. However, the proposed seaward boundary from Rame Head to Yealm Head includes a region of open exposed rocky coastline, together with an expanse of deeper open water. As Moore (1995) summarises the area: "a very large inlet with extensive areas of fully marine and species rich hard substrata and sediments in the Sound....... Littoral and sublittoral bedrock biotopes in the Sound are particularly well developed and extend from the open coast extremely sheltered limestone with rock-boring fauna...".

Smith & Moore (1996) provide a detailed account of the area, though their seaward limit, from Penlee Point to Renney Rocks, was somewhat inshore of the proposed boundary of the SAC. Hiscock & Moore (1986) also covered the area. Moore (1995) lists in his Appendix 4 the very wide range of sublittoral rock biotopes occurring in the area. These include circalittoral rock biotopes characteristic of variable and reduced salinities (SRK.SUB, SRK.DEN, SRK.DYS, SRK.LOW), and also those characteristic of very sheltered conditions (SRK.SUB, SRK.LIME, SRK.COD).

There is clearly a diversity and fair abundance of CFT biotopes within this demonstration CFT site, with those in extreme shelter and subject to variable salinity of particular interest. It has been shown earlier that a number of CFT biotopes and important species have limited distributions in the south-west, and Plymouth Sound and Estuaries is the only demonstration SAC within that area. Consequently the CFT biotopes merit serious consideration.

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