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Ascophyllum nodosum
Image courtesy of Dozens at wikimedia commons and the CC BY-SA 3.0 license.
Ascophyllum nodosum
Taxonomic Group: Algae
Common name: KNOTTED WRACK


Ascophyllum nodosum is a brown algae commonly known as Knotted Wrack. It is an Arctic-Boreal species being native to both coasts of the North Atlantic including the White Sea, Iceland, Greenland, and Baffin Island. Small introduced populations have been reported from San Francisco Bay, California; Puget Sound, Washington; Beaufort, North Carolina and Taranto, Italy; but there are no known established populations. An introduced population in San Francisco was successfully eradicated by manual picking in 2002. This species is often used as packing material for seafood and introduced specimens may represent discarded bait-packing material. On the West Coast of North America, A. nodosum may have been a vector for invasive invertebrates and algae from the Atlantic, such as Carcinus maenas and Littorina saxatilis.

* 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. .
National Exotic Marine and Estuarine Species Information System.
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Marine Invasions Lab
Smithsonian Environmental Research Center

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