Biodiversity & Conservation

Bugula spp. and other bryozoans on vertical moderately exposed circalittoral rock



Image Rohan Holt - Bugula spp. and other bryozoans on vertical moderately exposed circalittoral rock Image width ca XX m.
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Distribution map

CR.C.FaV.Bug recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats

Recorded distribution in Britain and Ireland

Recorded from only a few sites in the British Isles, including Orkney, Portland Harbour, Fowey estuary, the Lleyn Peninsula, Bardsey and west Anglesey. However, the biotope has been recorded as parts of other habitats and is probably, therefore, under recorded.

Habitat preferences

Temperature range preferences - Data deficient

Water clarity preferences - High clarity / Low turbidity
Medium clarity / Medium turbidity
Low clarity / High turbidity

Limiting Nutrients - Data deficient

Other preferences - Steep, vertical or overhanging hard substrata.

Additional information

The abundance of bryozoans is positively correlated with supply of stable hard substrata and hence with current strength (Eggleston, 1972b; Ryland, 1976). The community stability and diversity also requires stable substrata (Osman, 1977; Dyrynda, 1994). Water movement is essential for suspension feeders such as hydroids, bryozoans, sponges, amphipods and ascidians to supply adequate food, remove metabolic waste products, prevent accumulation of sediment and disperse larvae or medusae. Animal communities tend to dominate steep, vertical or overhanging surfaces, while macroalgae tend to dominate horizontal or gently sloping surfaces (< 60°) (Hartnoll, 1983). Steep or vertical surfaces reduce incident light, reduce siltation and may prevent settlement by algal spores, which tend to roll down hill (see Norton, 1992, Hartnoll, 1983). Species composition varies with depth, with decreasing numbers of foliose or filamentous algae due to light attenuation, and increasing numbers of species adapted to unidirectional flow (e.g. planar species of hydroids) than oscillatory flow as the effects of wave action attenuate (Riedl, 1971; Hiscock, 1983).

This review can be cited as follows:

Tyler-Walters, H. 2002. Bugula spp. and other bryozoans on vertical moderately exposed circalittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 29/11/2015]. Available from: <>