Threat: Habitat alteration
- golden brown with a lighter-coloured stem
- very wavy margins on the stipe, or stem, giving it a ridged appearance.
- branched holdfast, or root
- broad, flattened blade with a distinct midrib and wavy margins.
- forms a dense ‘forest’ which blocks light and outcompetes native species
- due to its rapid annual growth, can colonise areas where native seaweeds would not usually survive.
- infestations can foul shellfish beds and cages, and slow shellfish growth by restricting the flow of water into cages
- most likely to affect sheltered locations, harbours and pontoons and may become a major harbour pest.