Biodiversity & Conservation

Seaweeds in sediment (sand or gravel)-floored eulittoral rockpools



Image Tom Mercer - Seaweeds in sediment (sand or gravel)-floored eulittoral rockpools. Image width ca 1 m.
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Distribution map

LR.LR.Rkp.SwSed recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

Text page icon Habitat description

Map icon Distribution of biotope in Britain and Ireland Scattered distribution around the coasts of Britain and Ireland.
National importance Common

Text page icon Description of biotope

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

Rockpools with sediment floors support distinct communities of scour-tolerant algae. Deep pools with sediment are similar to LR.FK, and are typically dominated by fucoids and kelps (Fucus serratus, Laminaria digitata, Laminaria saccharina and Saccorhiza polyschides). Areas of hard substrata near to the interface with the sediment are, however, characterized by a range of sand-tolerant algae such as Furcellaria lumbricalis, Polyides rotundus, Ahnfeltia plicata and Rhodothamniella floridula (compare with LR.FK). Chorda filum may occur attached to pebbles and shells embedded within the sediment. In pools with large areas of sand, infaunal species such as Arenicola marina and Lanice conchilega often occur. The seagrass Zostera spp. may occur in some pools where stable sand is present. Shallow rockpools with cobble and pebble floors, often with an underlying layer of sediment, support red algal tufts (Mastocarpus stellatus mixed with Ceramium spp., Calliblepharis ciliata and Cystoclonium purpurea and green algae). (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

Additional information icon Additional information

Factors such as pool depth, surface area, volume, orientation to sunlight, shading, internal topography, sediment content and type, together with wave exposure, shore height, and hence flushing rate, and the presence of absence of freshwater runoff, results in large spatial variation in community structure, even between adjacent pools at the same shore height (Ganning, 1971; Metaxas & Scheibling, 1993). Individual rockpools and the communities that occupy them are highly variable. The above biotope description includes a wide variety of rockpool communities, from deep macroalgal dominated pools to shallow sediment filled rockpools that support only a few red algae. As a necessity, therefore, the review that follows is broad in nature.

This review can be cited as follows:

Tyler-Walters, H. 2005. Seaweeds in sediment (sand or gravel)-floored eulittoral rockpools. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 27/11/2015]. Available from: <>