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Wire Weed

HomeMarine Algae & SeagrassWire Weed

Wire Weed

Sargassum muticum

This invasive seaweed, introduced from the Pacific, forms dense tangles that can entangle marine life or foul boat propellers. Its wire-like stems and tiny floats make it easy to identify once you know what to look for. Around Lihou, large patches may appear in calm, shallow pools, potentially outcompeting native seaweeds for space and light.

  • Habitat: Shallow, sheltered waters and rockpools in the lower intertidal, often near marinas or boat moorings.
  • When to See: Year-round
  • Length: Fronds can exceed 2 m in length, with small air bladders.