Japanese seaweed / Wakame (Undaria pinnatifida)
Introduction
Japanese seaweed (or wakame) 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.
Identification
Japanese seaweed
Undaria pinnatifida
Key features:
- Can grow up to 1-3m tall
- Green-brown fonds
- Leaves stop short of base
- Frilly base
- Hold fast
- Midrib up to 3cm wide
Known locations:
- Tas and Vic
- Not known to occurr in NSW
Habitat:
- Can be highly invasive and grow rapidly into dense beds
- Overgrows and excludes native algal species
Similar native species
These native species may be confused with this marine pest.
Cray weed/Strap weed
Phyllospora comosa
Key features:
- No midrib or base
- Long strand-like fronds with sawtooth edge, air sacks for floats
- Up to 3m tall
Habitat:
- Exposed rocky reef up to 20m depth
Common kelp
Ecklonia radiata
Key features:
- No midrib or base
- Often has spines, brown fronds, up to 2m tall
- Appearance varies with depth (longer, smoother fronds in deep water)
Habitat:
- Moderately exposed rocky reefs up to 44m depth
Bull kelp
Durvillaea potatorum
Key features:
- No midrib or base
- Large bulky fronds
- Up to 8m tall
Habitat:
- Exposed rocky reef up to 30m depth
How can you help?
Learn to recognise, and be aware of, the Japanese seaweed (or wakame) so that you can report any suspected new sighting.
If you see this pest in NSW, please report it immediately
- Note the exact location
- If possible take a photo and/or collect a sample
- Freeze sample in a plastic bag
- Report your sighting
