Biodiversity & Conservation

Rhodothamniella floridula on sand-scoured lower eulittoral rock



Image Kate Northen - Sand tolerant red algae on lower shore. Image width ca 60 cm (foreground).
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Distribution map

LR.MLR.BF.Rho 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 Recorded in locations all around the British Isles, particularly along the Northumbrian and south coasts.
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

Lower eulittoral and sublittoral fringe sand-scoured bedrock and boulders are often characterized by canopy algae (usually Fucus serratus), beneath which a mat of the sand-binding red alga Rhodothamniella floridula occurs. These mats can also form distinct areas without Fucus serratus. The small hummocks of Rhodothamniella floridula also contain other small red and brown algae and species of worm and amphipod may burrow into the Rhodothamniella floridula mat. Other sand-tolerant algae, such as Polyides rotundus, Furcellaria lumbricalis, Gracilaria verrucosa and Cladostephus spongiosus, may be present. Ephemeral algae such as Ulva spp., Ulva spp. and Porphyra spp. may occur. Where sand scour is more severe, fucoids and Rhodothamniella floridula may be rare or absent and these ephemeral algae dominate the substratum (MLR.EntPor - Porphyra purpurea or Ulva spp. on sand-scoured mid or lower eulittoral rock). (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

Additional information icon Additional information

As the dominance of species varies from one to another so the colour of these populations may range from bright or dark green to various sandy, brownish-red shades, the whole contrasting sharply with adjacent areas of Fucus spp. (Lewis, 1964).

This review can be cited as follows:

Riley, K. 2002. Rhodothamniella floridula on sand-scoured lower eulittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 30/11/2015]. Available from: <>