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Wakame - Invasive Species Information

High Risk

Reproduction: prolific spore production and its ability to foul structures both in its macroscopic and microscopic forms. It spreads rapidly and geographically distant populations can appear in a short space of time. It is transported to new areas by human activities in both its highly visible sporophyte, or as the microscopic gametophyte and spore stages in its life cycle.

Wakame - Undaria pinnatifida Fond

Wakame stand

Wakame or Japanese seaweed, is a highly invasive seaweed that can grow to 3m in length and has green-brown fronds. It grows in sheltered temperate waters, forming dense forests at depths of up to 15m and can quickly displace native habitats.

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This seaweed is green and golden-brown in colour with a lighter coloured stem and a branched holdfast (for attachment to the substrate). The stipe has very wavy edges, giving it a ridged appearance. Undaria has a broad, attened leaf shaped blade with a distinct midrib and wavy margins. 

Wakame - Undaria pinnatifida Fonds
Wakame - Undaria pinnatifida growth stages

How To Identify Wakame?

Colour: Green-brown fonds can grow up to 1-3m tall

Leaves: stop short of base, Midrib up to 3cm wide with frilly base Hold fast

Wakame - Undaria pinnatifida ID Guide

Wakame - Undaria pinnatifida ID Guide

Wakame leaves

Wakame stand

Why Is Wakame A Problem?

Can be highly invasive and grow rapidly into dense beds

Overgrows and excludes native algal species preventing biodiversity and altering marine food chain. as an opportunistic species, takes advantage of areas disturbed by human activities or grazing by herbivores such as urchins and is also known to grow in areas not normally occupied by native seaweeds where it may have a high degree of impact. 

What Is Wakame - (Undaria pinnatifida)?

Habitat: Aquatic. Costal areas.
Distribution in Ireland: Present around coastal waters

Status: Established
Family name: Alariaceae

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European Communities (Birds and Natural Habitats) Regulations 2011 non-native invasive plant species A-Z (Updated 2017)

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There are currently 35 invasive plant species listed in the European Communities (Birds and Natural Habitats) Regulations (annex 2, Part 1)...

 

Click on a species from the following list to find out more regarding non-native species subject to restrictions under Regulations 49 and 50.

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  1. American Skunk-Cabbage - Lysichiton americanus

  2. Brazilian Giant-Rhubarb - Gunnera manicata

  3. Broad-Leaved Rush - Juncus planifolius

  4. Cape Pondweed - Aponogeton distachyos

  5. Cord-Grasses - Spartina (all species and hybrids)

  6. Curly Waterweed - Lagarosiphon major

  7. Dwarf Eel-Grass - Zostera japonica

  8. Fanwort - Cabomba caroliniana

  9. Floating Pennywort - Hydrocotyle ranunculoides

  10. Fringed Water-Lily - Nymphoides peltata

  11. Giant Hogweed - Heracleum mantegazzianum

  12. Giant Knotweed - Fallopia sachalinensis

  13. Giant-Rhubarb - Gunnera tinctoria

  14. Giant Salvinia - Salvinia molesta

  15. Himalayan Balsam - Impatiens glandulifera

  16. Himalayan Knotweed - Persicaria wallichii

  17. Hottentot-Fig - Carpobrotus edulis

  18. Japanese Knotweed - Fallopia japonica

  19. Large-Flowered Waterweed - Egeria densa

  20. Mile-a-Minute Weed - Persicaria perfoliata

  21. New Zealand Pigmyweed - Crassula helmsii

  22. Parrots Feather - Myriophyllum aquaticum

  23. Red Alga - Grateloupia doryphora

  24. Rhododendron - Rhododendron ponticum

  25. Salmonberry - Rubus spectabilis

  26. Sea-Buckthorn - Hippophae rhamnoides

  27. Spanish Bluebell - Hyacinthoides hispanica

  28. Three-Cornered Leek - Allium triquetrum

  29. Wakame - Undaria pinnatifida

  30. Water Chestnut - Trapa natans

  31. Water Fern - Azolla filiculoides

  32. Water Lettuce - Pistia stratiotes

  33. Water-Primrose - Ludwigia (all species)

  34. Waterweeds - Elodea (all species)

  35. Wireweed - Sargassum muticum

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