Laminaria digitata

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Oarweed
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Sea Girdle
Sea Tangle
Kombu
Gaeilge
Coirleach
Leathach Fada
Leathrach
Feamannach Dubh
Leath
Learach.

Laminaria digitata during low tide at Spiddál beach

Description

Laminaria digitata is a brown-golden kelp of the lower shore that forms dense beds at and below the low water mark. It is generally very similar in appearance to L. hyperborea. It grows up to 2 m long and 60 cm wide. The stipe is long, smooth, bending and oval in cross-section. The holdfast is a cluster of strong, thin, flat, spreading, branching, intertwining, root like processes. The frond is flat, large, rubbery and smooth with finger-like sections, which may be torn or indented by wave action.  The stipe is not rigid enough to bear the weight of the frond in air, so it lies prostrate on the flat or hanging from rocks, when exposed during low water.

Distribution

Laminaria digitata is a very common kelp of the low water margins around the Irish as well as the north European and eastern north American coast. In clear waters it can be found extending down to a depth of 10 meters so it tends to form narrower beds than its look-alike L. hyperborea.

Variable densities of L. digitata have been noted around the whole extent of the coast generally less than the amount of L hyperborea present. Laminaria digitata thrives in fairly exposed areas or in more sheltered areas with strong tidal currents and is sensitive to lower salinities, preferring a salinity greater than 20 ppt.

Laminaria digitata cast upon the beach

Nutritional analysis

Laminaria digitata during low tide at Spiddál beach