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.

• Clatharina coriacea
• Pachymatisma johnstonia
• Cliona celata
• Stelligera rigida
• Haliclona viscosa
• Dysidea fragilis
• Nemertesia antennina
• Actinothoe sphyrodeta
• Scrupocellaria reptans
• Bicellaria ciliata
• Bugula flabellata
• Bugula plumosa
• Bugula turbinata
• Aplidium punctum
• Lissoclinum perforatum

• Leptopsammia pruvoti
• Hoplangia durotrix
• Alcyonium hibernicum

This biotope is dominated by species of the erect bryozoan Bugula, which if lost would result in loss of the biotope as described. The faunal turf of bryozoans and hydroids such as Tubularia indivisa and Nemertesia antennina provide substrata for many species or epizooics, refuges for mobile species, and are active suspension feeders, important in the structure and succession of the biotope. The sensitivity of hydroids has been represent by Nemertesia ramosa with reference to reviews of hydroid biology . Similarly, ascidians and sponges are important competitors for space within the community. Their sensitivity has been represented by Clavelina lepadiformis, Morchellium argus and Halichondria panicea respectively. Echinoderms are mobile generalist grazer and predators that affect community succession, recruitment and diversity and have been represented by Echinus esculentus and Asterias rubens.

Circalittoral faunal turf biotopes support a large number of sessile, interstitial, and mobile cryptofauna (Hartnoll, 1998). The MNCR identified ca 370 conspicuous species within this biotope, although a smaller proportion of species is likely to occur in any one example of the biotope.

Some examples of this biotope may include the nationally rare sunset cup coral Leptopsammia pruvoti and Weymouth cup coral Hoplangia durotrix, and the nationally scarce soft coral Alcyonium hibernicum (Keith Hiscock, pers comm.).