Biodiversity & Conservation

Laminaria saccharina, Chorda filum and dense red seaweeds on shallow unstable infralittoral boulders or cobbles

IR.MIR.SedK.LsacChoR

MIR.LsacChoR

Image Keith Hiscock - Saccharina latissima, Chorda filum and dense red seaweeds on shallow unstable infralittoral boulders or cobbles. Image width ca 1m in foreground.
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Distribution map

IR.MIR.SedK.LsacChoR recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats

Ecological and functional relationships

The species present in this biotope thrive particularly in conditions of disturbance. They are mainly annual species with rapid growth or are perennial species that may die back in winter and persist as crusts or basal portions that survive abrasion during winter storms. Grazing species such as sea urchins do not survive well in conditions of abrasion and so seaweeds can thrive.

Seasonal and longer term change

It is expected that there will be considerable reduction in the abundance of foliose seaweeds especially following the summer. The reduction is partly because of grazing, partly seasonal disintegration of fronds and partly abrasion. Annual seaweeds start to colonize and perennial seaweeds to regrow in about April and can be expected to be fully grown by May.

Habitat structure and complexity

This is a complex habitat with semi-stable hard substratum supporting epibiota through to sediments supporting infauna. The fronds of seaweeds also provide significant surfaces especially for epibiota and for gastropods. The holdfasts of Saccharina latissima and, where present, of Saccorhiza polyschides provide a habitat for cryptic animal species.

Productivity

This biotope would appear to be productive of organic matter from seaweeds especially.

Recruitment processes

The dominant and characteristic species are recruited from planktonic larvae and spores. Other species such as fish and crustaceans are mainly transitory once settled.

Time for community to reach maturity

Providing that sources of larvae, spores and mobile animals are nearby, the biotope would develop rapidly on new substrata so that, in appearance based on visually dominant species, it would be likely to be established in a year. However, recruitment of a full range of species, especially molluscs and some algae would take longer so that a dynamic stability would probably be reached only after about three years.

Additional information

No information was available on the infauna associated with this biotope although it is expected that species will be tolerant of displacement.

This review can be cited as follows:

Hiscock, K. 2001. Laminaria saccharina, Chorda filum and dense red seaweeds on shallow unstable infralittoral boulders or cobbles. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 25/05/2013]. Available from: <http://www.marlin.ac.uk/habitatecology.php?habitatid=363&code=1997>