Biodiversity & Conservation

Wakame - Undaria pinnatifida

Undaria pinnatifida

Image Keith Hiscock - Undaria pinnatifida growing on pontoons at Queen Annes Battery, Plymouth Sound. Image width ca 1 m.
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Distribution map

Undaria pinnatifida recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

Why do the maps differ?

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Undaria pinnatifida is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Ochrophyta Brown and yellow-green seaweeds
Class Phaeophyceae
Authority (Harvey) Suringar
Recent synonyms None
Map icon Recorded Distribution in Britain and Ireland Recorded from the Hamble (Solent), Isle of Wight, Torquay, Plymouth and Jersey.
Habitat information icon Habitat information Wakame is an introduced species of brown seaweed in Europe found subtidally, often growing on man-made structures such as marina pontoons. In its native habitat, it occurs in dense stands, forming a thick canopy on a wide range of shores from low tide level down to 15 m in clear waters.
Text page icon Description Undaria pinnatifida or wakame is a large brown kelp with a branched holdfast giving rise to a stipe. Just above the holdfast, the stipe has very wavy edges, giving it a corrugated appearance. The stipe gives rise to a blade that is broad, flattened and lanceolate. It has a distinct midrib. The margins of the blade are wavy. Plants can reach an overall length of one to three metres. Undaria pinnatifida is an annual species with two separate life stages.
Identifying features
  • Branched holdfast.
  • Stipe wavy or corrugated above holdfast.
  • Blade lanceolate and broad with a midrib.
  • Usually 1.5-2 m long.
  • Dark brown frond.
Additional information icon Additional information

Wakame is a laminarian kelp indigenous to the temperate regions of Japan, China and Korea (Stuart, 2003). It has been spread around the world by international shipping and mariculture. It has extended its range to include 12 countries on four continents since 1981 (Stuart, 2003). Wakame is a non-native species, which may cause displacement of native species. It was first recorded in the UK from the Hamble Estuary in the Solent on 15 June 1994 (Farell & Fletcher, 2000). It tolerates a wide salinity and temperature range. Its morphological and reproductive characteristics make it a very successful invasive species. Undaria pinnatifida possesses a heteromorphic life cycle with alternation of generations between a diploid sporophyte and a haploid gametophyte (Aguilar-Rosas et al., 2004). It may be confused with Alaria esculenta but the corrugated stipe is distinctive.

Wakame is economically important as a food crop but is also a fouling organism. It is able to compete with native kelp species in the shallow sublittoral/infralittoral zone (Farrell & Fletcher, 2000). It is also effective in providing habitats, nursery areas and protective cover for many species. It grows well in estuarine conditions unlike many of the native kelp species (Farrell & Fletcher, 2000) .

This review can be cited as follows:

Judith Oakley 2007. Undaria pinnatifida. Wakame. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 09/02/2010]. Available from: <http://www.marlin.ac.uk/speciesinformation.php?speciesID=4547>