Invasion
Invasion Description
1st Records: White Rock, north of Vancouver/British Columbia/Straits of Georgia (1944, Scagel 1956); north of Vancouver/British Columbia/Buccaneer Bay Straits of Georgia; (1944, Scagel 1956)
Geographic Extent
AK/Sea Otter Sound (5/3/1974, Prince of Wales Island/Sea Otter Sound ( ALAJ00982, University of Alaska Southeast Herbarium, 55.8441667, -133.4536111); Ketchikan area/AK/Davidson Inlet (1977, Scagel et al. 1989); Queen Charlotte Islands/British Columbia/Skidegate Inlet, Hecate Straits (1981, Sloan 2004); Bamfield, Vancouver Island/British Columbia/Barkley Sound (2008, White and Orr 2011); Comox, Vancouver Island/British Columbia/Straits of Georgia; (1945, Scagel 1956); Campbell River, Vancouver Island/British Columbia/Straits of Georgia (2008, Choi et al. 2016); Nanaimo, Vancouver Island/British Columbia/Straits of Georgia (1948, Scagel 1956; 2008, Choi et al. 2016); White Rock, north of Vancouver/British Columbia/Straits of Georgia; (1944, Scagel 1956); north of Vancouver/British Columbia/Buccaneer Bay Straits of Georgia; (1944, Scagel 1956); 10 of 24 marinas/British Columbia/Pacific Ocean (Murray et al. 2011);Tsawwassen//British Columbia/Straits of Georgia (Mach et al. 2017); San Juan Islands/WA/Rocky and Andrews Bays, Straits of Juan de Fuca (1948, Scagel 1956); San Juan Islands/WA/Jackle and Argyle Lagoons (19, Straits of Juan de Fuca (1948, Scagel 1956); northern Puget Sound (Bellingham area?)/WA/'northern Puget Sound (Giver,1999 ; Riggs 2011); Birch Point and Cherry Point/WA/Straits of Georgia (Whatcom County Marine Resources Committee 2007, http://www.whatcom-mrc.wsu.edu/Fact_Sheets/index.htm); Steamboat Island/WA/unction of Totten Inlet and Eld Inlet, Puget Sound (2000, Cohen et al. 2001); Myrtle Edwards Park, Seattle/WA/Elliott Bay, Puget Sound (2000, Cohen et al. 2001); Pier 90 Beach, Seattle/WA/Elliott Bay, Puget Sound (2000, Cohen et al. 2001); Seacrest Park, Seattle/WA/Elliott Bay, Puget Sound (2000, Cohen et al. 2001); Point Whitney, Jefferson County/WA/Quilcene Bay, Hood Canal (1950, Scagel 1956); WA/central basin, Puget Sound (Dethier and Scoch 2005); Mill Point, Port Discovery/WA/Discovery Bay, Straits of Juan de Fuca (Scagel 1956); WA/Neah Bay, Straits of Juan de Fuca (1952, Scagel 1956)
Vectors
| Level | Vector |
|---|---|
| Probable | Oyster Accidental |
Regional Impacts
| Ecological Impact | Competition | |
| The invasion of Sargassum muticum resulted in displacement of native algae in the San Juan Islands, northern Puget Sound. A removal experiment resulted in recovery of native kelps (Britton-Simmons 2004). Modeling and experiments indicated that S. muticum invasions required a combination of disturbance and high propagule pressure (Britton-Simmons et al. 2008). In British Columbia, S. muticum rapidly colonized cleared areas, followed by decreased recruitment of native seaweeds (de Wreede 1983, cited by Schaffelke and Hewitt 2007). At low levels of abundance, S. muticum had few impacts, but at high levels, S. muticum excludes natives through competition for light (primarily) and space, resulting in reduced diversity and productivity. The impact increased with S. muticum density in a non-linear fashion (White and Shurin 2011). | ||
| Ecological Impact | Food/Prey | |
| There were fewer Green Sea Urchins (Strongylocentrotus droebachiensis) at invaded sites, apparently because they found S. muticum unpalatable (Britton-Simmons 2004). However, the snail Lacuna vincta was 2-9X more abundant on S. muticum than on native algae. This preference seems to have been acquired in the last 30 years (Britton-Simon et al. 2011). | ||
| Ecological Impact | Habitat Change | |
| In the San Juan Islands, Washington, Sargassum muticum supported a total of 107 epifaunal taxa, and on average supported 20 species per plant, compared to 10 species per plant on the native kelp Laminaria saccharina. Epifaunal diversity increased in area invaded by S. muticum (Giver 1999). | ||