Invasion
Invasion Description
1st Record: CA/Humboldt Bay ("present for at least 30 years", Boyd et al. 2002)
Geographic Extent
CA/Humboldt Bay ("present for at least 30 years", Boyd et al. 2002; 2000, Ruiz et al., unpublished data); Woodley Island Marina/CA/Humboldt Bay (2001, Fairey et al. 2002); Woodley Island Marina/CA/Humboldt Bay (Nelson 2009); Charleston Boat Basin/OR/Coos Bay (1978, Carlton 1989; 2003, de Rivera et al. 2005a); Port Adams Jetty, Coos Bay/OR/Coos Bay (1988, Hewitt 1993); Umpqua Triangle, Reedsport/OR/Winchester Bay (1986, Carlton 1989; Nonindigenous Aquatic Species Program 2010)); Nahcotta Small Boat Basin/WA/Willapa Bay 22 May 2000, Cohen et al. 2001, 46° 30’ 02.348” N; 124° 01’ 50.635)
Vectors
| Level | Vector |
|---|---|
| Alternate | Hull Fouling |
| Alternate | Oyster Accidental |
Regional Impacts
| Ecological Impact | Competition | |
| In fouling plate experiments in Humboldt Bay, Nelson (2009) found that colonial tunicates (Botryllus schlosseri and Botrylloides violaceus), growing in sheets, were able to quickly occupy space on fouling plates, but did not decrease recruitment or species richness. | ||
| Ecological Impact | Food/Prey | |
| In feeding trials, the native crabs Hemigrapsus oregonensis, the flatworm Eurylepta leoparda and the nudibranch Hermissenda crassicornis fed heavily on the native tuinicate Distaplia occidentalis but at much lower rates on the non-native Botryllus schlosseri and Botrylloides violaceus) (Kincaid and de Rivera 2020). | ||