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Sargassum muticum
Image courtesy of Graça Gaspar, Wikimedia Commons, and the Creative Commons CC BY-SA 3.0 License
Sargassum muticum
Taxonomic Group: Algae
Common name: WIREWEED


Sargassum muticum is a large brown seaweed, which is native to the Western Pacific, spanning from China and South Korea to Japan and Southern Russia. It has been introduced to the Eastern Pacific (Mexico to Alaska) and Eastern Atlantic (Morocco to Norway), and has spread widely, spanning from tropical to cold waters. Genetic studies indicate that introduced populations originated from the Seto Inland Sea, Japan and were likely introduced with Pacific Oyster (Crassostrea gigas) shipments. It grows attached to hard structures and is found in a variety of habitats including tide pools, subtidal reefs, rocky benches, pebbles, stones, shells, ropes, docks, and vessel hulls. In introduced locations it has had varied ecological effects on native communities. In some cases, it decreased native algal diversity and abundance, but in others, its complex stem structure increases invertebrate and fish abundance.

* Content for this species is based on the literature and peer review is pending - if you have comments or feedback please contact Paul Fofonoff at

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Fofonoff PW, Ruiz GM, Steves B, Simkanin C, & Carlton JT (2018)
National Exotic Marine and Estuarine Species Information System.
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Marine Invasions Lab
Smithsonian Environmental Research Center

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