Biodiversity & Conservation

Laminaria saccharina, Chorda filum and filamentous red seaweeds on sheltered infralittoral sediment



Image Anon. - Saccharina latissima, Chorda filum and filamentous red seaweeds on sheltered infralittoral sediment. Image width ca 50 cm in foreground.
Image copyright information

  • #
Distribution map

SS.SMp.KSwSS.LsacCho recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats

Ecological and functional relationships

The species occurring in this biotope appear to be largely independent of each other except that the fronds of Saccharina latissima are likely to be colonized by epibiota, especially solitary ascidians and bryozoans, as well as supporting mobile gastropods such as Gibbula cineraria. Sea urchins Psammechinus miliaris might also feed on the fronds.

Seasonal and longer term change

No information has been found although it would be expected that filamentous red seaweeds especially might be more abundant in spring and summer than autumn and winter.

Habitat structure and complexity

There are a wide range of substrata available for colonization in this biotope and therefore potential for high biodiversity. Sediments are colonized by infauna including conspicuous species such as the burrowing anemone Cerianthus lloydii and the lugworm Arenicola marina, but also by polychaetes and bivalve molluscs. Pebbles and cobbles will be colonized by attached algae but also by barnacles, tube worms and encrusting bryozoans. Kelp holdfasts provide shelter for a range of mobile species, including amphipods, decapods and echinoderms, whilst the fronds are colonized by the grazing gastropods, Gibbula cineraria and Calliostoma zizyphinum. Sea urchins, Psammechinus miliaris, frequently graze on the kelp fronds.


The algae which dominate this biotope are primary producers themselves contributing to the supply of detritus that is used by secondary producers. Sea urchins, Psammechinus miliaris, more directly feed on the fronds of the kelp.

Recruitment processes

Recruitment of characterizing species in the biotope is from planktonic sources. Mobile species such as the shore crab Carcinus maenas and the common starfish Asterias rubens will migrate into the biotope as juveniles and adults. However, other mobile species such as the topshell Gibbula cineraria and the sea urchin Psammechinus miliaris are unlikely to move far once settled.

Time for community to reach maturity

Most of the epibiota species in the biotope are known to be rapid colonizing and fast growing, including the dominant species. However, sediment infauna is probably more slow to colonize and develop. Some species such as Cerianthus lloydii may be very slow to colonize. Overall, because of the dominance of rapid settling and fast growing species, the biotope develop rapidly but recruitment of a full complement of species may take several years.

Additional information

No biotope specific studies are known to have been undertaken.

This review can be cited as follows:

Hiscock, K. 2001. Laminaria saccharina, Chorda filum and filamentous red seaweeds on sheltered infralittoral sediment. 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: <>