A Perspective on Biogenic Reefs and SACs
The distribution of major examples of biogenic reefs is given by
species in Table 3 and Figure 2, both within cSACs and pSACs, and elsewhere.
No currently proposed SACs were selected specifically on the basis that
they contain biogenic reefs. However, biogenic reefs are sub-features of other
Annex I features such as reefs, estuaries or large shallow
inlets and bays. In some cases biogenic reefs are specifically mentioned as reasons
why a site is a particularly good example of an Annex 1 habitat e.g. Mytilus in
Morecambe Bay, Modiolus in Strangford Lough, Lleyn Peninsula and the Sarnau and
Loch Maddy; Sabellaria alveolata in the Solway Firth and Morecambe Bay.
There are candidate SACs selected on the basis of the presence of
reefs which do have substantial areas of Modiolus reef (Lochs Duich,
Long and Alsh, Lleyn Peninsula and the Sarnau), Sabellaria alveolata reef (Lleyn
Peninsula and the Sarnau); and probably Sabellaria spinulosa reef (Lleyn Peninsula
and the Sarnau; possibly Berwickshire and the North Northumberland coast) and Mytilus
reef (Berwickshire and the North Northumberland coast) (Table 3 and Figure 1).
It is worth noting that an SAC cannot be designated on the basis of an
intertidal reef area unless there is also contiguous subtidal reef interest (Brown et al.,
1997). In the case of Mytilus and Sabellaria alveolata reefs, which are
usually intertidal but may also occur in the shallow subtidal, they are very likely to
occur as interest features of SACs designated as estuaries, large
shallow inlets and bays, or even mud and sand flats not covered by sea
water or sandbanks which are slightly covered by sea water at all times,
(see Table 3 and Figure 1). Sabellaria alveolata and Mytilus edulis also
occur within the Cardigan Bay cSAC, designated on the presence of bottlenose dolphins, Tursiops
truncatus. The Wash and North Norfolk Coast cSAC almost certainly has Sabellaria
spinulosa reefs which are probably best regarded as an interest feature under
large shallow inlets and bays (Table 3 and Figure 1). Modiolus forms an
interest feature of large shallow inlets and bays in Loch Maddy and Strangford
Serpulid reefs have an extremely limited distribution within the UK
(presently known only from one, or possibly two, Scottish sea lochs) and none occur within
cSACs or pSACs.