Biodiversity & Conservation

Piddocks with a sparse associated fauna in upward-facing circalittoral very soft chalk or clay

CR.MCR.SfR.Pid


MCR.Pid

Image Roger Covey - Piddocks with a sparse associated fauna in upward-facing circalittoral very soft chalk or clay. Image width ca 30 cm.
Image copyright information

Distribution map

CR.MCR.SfR.Pid recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)


  • EC_Habitats

For a list of 2004 characterising species please see the JNCC website.

Species indicative of sensitivity

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.

Community Importance Species name Common Name
Key structural Pholas dactylus Common piddock
Key functional Polydora ciliata A bristleworm
Important characterizing Urticina felina Dahlia anemone
Important characterizing Halichondria panicea Breadcrumb sponge

Explanation

Piddocks, such as Pholas dactylus, are the key structuring species giving the name to the biotope. They create an uneven surface, and empty burrow holes, on chalk or clay platforms which provides habitats for other animals greatly increasing species diversity of the biotope (Pinn et al., in press). The top centimetre or so of the chalk is often riddled with large numbers of the primarily deposit feeding Polydora ciliata. In silty areas tubes built by Polydora ciliata can agglomerate and form layers of mud up to an average of 20cm thick, occasionally to 50cm. These layers can eliminate other fauna and flora, or at least can be considered as a threat to the ecological balance achieved by some biotopes (Daro & Polk, 1973). The species may also be important to nutrient exchange at the water-sediment interface. Urticina felina is an important characterizing species as a passive carnivore and with a potential role in nutrient exchange. The sponge, Halichondria panicea is characteristic of the biotope and can be a major space occupier. Where massive growths of the sponge occur, they may provide a significant habitat for other species.

Additional information


This review can be cited as follows:

Hill, J.M. 2008. Piddocks with a sparse associated fauna in upward-facing circalittoral very soft chalk or clay. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 22/10/2014]. Available from: <http://www.marlin.ac.uk/habitatreproduction.php?habitatid=152&code=2004>