Undaria pinnatifida or wakame is a brown alga originating from Northeast Asia, where it is grown for consumption. It is an opportunistic species that can spread very fast by attaching itself to ship hulls. After the species was introduced in 1971 in the Mediterranean via oyster farming, the seaweed was grown in the French Bretagne as food. Wakame often forms dense kelp forests, which compete with indigenous plants and animals for available space and light. In Belgium, the species can be found since 1999, mainly in the harbour of Zeebrugge.