Biodiversity & Conservation

Ulva spp. on freshwater-influenced or unstable upper eulittoral rock



Image David George - Fallen chalk blocks covered in Enteromorpha. Image width ca 4 m.
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Distribution map

LR.FLR.Eph.Ent recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats

Text page icon Habitat description

Map icon Distribution of biotope in Britain and Ireland The biotope may be found especially in the inlets of S.W and S.E Britain and on chalk coasts, and elsewhere in the British Isles where the substratum is relatively soft and/or prone to physical disturbance and freshwater runoff.
National importance Uncommon

Text page icon Description of biotope

For a full description of this biotope including characterizing species, distribution, survey information and references visit JNCC

Upper shore hard substrata that is relatively unstable (e.g. soft rock) or subject to considerable freshwater runoff is typically characterized by a dense mat of the green filamentous algae Ulva intestinalis and Ulva prolifera, often together with the red alga Porphyra umbilicalis. This band of Ulva spp. is usually found above the Fucus spiralis zone (SLR.Fspi) and may replace the Pelvetia canaliculata zone (MLR.PelB). (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

Additional information icon Additional information

The biotope is characterized by seaweeds and is generally devoid of fauna, except for the occasional limpet, Patella vulgata, winkles, Littorina littorea, Littorina saxatilis and barnacles Semibalanus balanoides.

This review can be cited as follows:

Budd, G.C. 2004. Ulva spp. on freshwater-influenced or unstable upper eulittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 25/11/2015]. Available from: <>