Wireweed
Sargassum muticum
Wireweed is an invasive brown alga now common in Guernsey. It grows in dense, tangled mats along sheltered rocky shores and in quiet pools. Its wiry, branching fronds can entangle marine life and disrupt native seaweed communities.
- Habitat: Shallow, sheltered coastal waters and rockpools where wave action is minimal.
- When to See: Year-round
- Length: Fronds can exceed 2 m in length, with small air bladders.