Invasion
Invasion Description
1st Record: Hercmoulin and Dielette/France/English Channel (1978, Critchley et al. 1993)
Geographic Extent
Hercmoulin-Saint Malo (Normandy)/France/English Channel (1978, Farnham 1980; Critchley et al. 1983); Belsher and Pommelec 1988; Channel Islands/English Channel (1979, Department of the Environment, States of Jersey 2017); Cape d'Erquy-Roscoff, Brittany/France/English Channel (1980, Critchley et al. 1983; Belsher and Pommelec 1988); Guilvenec/Brittany/France/Bay of Biscay (1984, Belsher and Pommelec 1988); Brittany/France/Etel Bay (1981, Critchley et al. 1983); continuous on coast of Brittany/France/Atlantic Ocean (Stiger-Pouvreau and Thouzeau 2015); France/Bay of Borgneuf (1985, Belsher and Pommelec 1988); La Rochelle/France/Pertuis Marennes-Oleron (1985, Belsher and Pommelec 1988)
Vectors
| Level | Vector |
|---|---|
| Probable | Oyster Accidental |
Regional Impacts
| Ecological Impact | Competition | |
| Sargassum muticum became the most abundant species in the intertidal of the French Atlantic coast, and was associated with a decrease in a native kelp (Laminaria digitata) (Belsher and Pommelec 1988; Cosson 1999, cited by Schaffelke and Hewitt 2007; Stiger-Pouvreau and Thouzeau 2015). It was also reported to colonize and displace Eelgrass (Zostera marina), in areas where the Eelgrass has declined, due to disturbance (Den Hartog 1997). | ||
| Ecological Impact | Habitat Change | |
| In turbid waters, Sargassum muticum replaces kelps, but provides habitat for fishes, crustaceans, and cuttlefish (Stiger-Pouvreau and Thouzeau 2015; Roux et al. 2021). Sargassum muticum does not directly compete with Eelgrass (Zostera marina, but when Eelgrass beds near Roscoff, France, are destroyed by natural shifts in the sediment, S.muticum quickly colonizes the empty spaces (den Hartog 1997). | ||
| Economic Impact | Fisheries | |
| Sargassum muticum can interfere with shellfishing and shellfish aquaculture, by covering the bottom, fouling shells, and equipment (Belsher and Pommelec1988); Stiger-Pouvreau and Thouzeau 2015) | ||
| Economic Impact | Shipping/Boating | |
| Sargassum muticum entangled propellers and hampered navigation in Saint-Malo, Saint-Guénolé, and the Gulf of Morbihan (1982-1986, Belsher and Pommelec1988) | ||