Wakame (Undaria pinnatifida)

Description: This golden-brown kelp grows in one plane (it is flat), with leaf-like pinnae attached to a central midrib that is usually lighter in color than the rest of the frond. Frilly, ribbon-like reproductive structures (sporophylls) can occur at the base of the frond. Each frond is about 1-3 m in length, and Wakame is often found in dense aggregations.

Habitat: Wakame can colonize a wide range of substrata in fairly protected water (such as bays and harbors). It ranges from the low tide mark down to 15 m in depth, but is especially abundant near the waterline on floating objects such as dock sides, boat hulls, and buoys.

Origin: Sea of Japan.

Invaded Areas: Southern and Baja California, Argentina, Europe, Australia, New Zealand, and Russia. Note: this species appeared in Monterey Harbor in 2001. Efforts to control and monitor this recent invasion will be greatly helped by early reports of any expansions of its local range.

Concerns: Wakame is intensely cultivated in Japan, and hence has great economic value. It is a popular Asian food item, responsible for giving miso soup its distinct taste. Wakame has been widely introduced, both intentionally and unintentionally, and has become extremely abundant in some invaded communities, outcompeting native species. Its spores settle on almost any surface, and therefore Wakame grows not only on hard bottom surfaces, but also other algae, sea grasses, and pier pilings.