Biodiversity & Conservation

To assess the sensitivity of the biotope, the sensitivity of component species is reviewed. Those species that are considered to be particularly indicative of the sensitivity of the biotope, and for which research has been undertaken in detail are shown below (see selection criteria). The biology of other component species of the biotope is also taken into account wherever information is known to the researcher.

• Armeria maritima
• Caloplaca marina
• Tephromela atra
• Ochrolechia parella
• Ramalina siliquosa
• Verrucaria maura
• Xanthoria parietina
• Ligia oceanica

The lichen flora provide some primary productivity but more importantly provide shelter and niches for the invertebrate fauna. A few species of acarid mites and tardigrades are closely associated with and possibly dependant on a few species of supralittoral lichen. Therefore, the sensitivity of the biotope is probably represented by the lichens alone.

Fletcher (1980) reported that almost 450 species of lichen occurred on mid-littoral and supralittoral rocky shores around Britain and represented about one third of the British lichen flora. Fewer species are likely to occur on a single shore, for example Fletcher (1980) suggested that a shore in Wales would typically support 150 lichen species while a Northumberland shore may only support 40-60 species. Pugh & King (1988) reported 77 species of acarid mites from the supralittoral, the majority from lichens and tidal debris, although the diversity of species varies with location. Morgan & Lampard (1986) reported 7 species of tardigrade from only 4 species of supralittoral lichen on the Great Cumbrae. The lichen flora probably also supports a variety of spring tails (Collumbola), maritime insects, pseudoscorpions and spiders that are not generally recorded in surveys, so that species richness is likely to be underestimated.