Invasion
Invasion Description
1st Record: Oakland/CA/Lake Merritt, San Francisco Bay (Rodholm 1932, cited by Carlton 1979).
In San Francisco Bay, the abundance and dominance of C. robusta varies with internnual cycles of precipitation and riverflow in the watershed. Ciona robusta at Richmond Marina, in the central Bay, is dominant during dry periods (28-33 PSU), and rare to absent during dry periods (22-28 PSU) (Chang et al. 2017).
Geographic Extent
Oakland/CA/Lake Merritt, San Francisco Bay (Rodholm 1932, 1960s-1970s, Carlton unpublished, cited by Carlton 1979); CA/San Francisco Bay (2000, Ruiz et al., unpublished data); Richmond Marina/CA/San Frncisco Bay (2010, Marrafini et al. 2017); Sausalito/CA/San Francisco Bay (Nydam and Harrison 2007. molecular ID)); Richmond Marina/CA/San Francisco Bay (Chang 2009; 2010, Marrafini et al. 2017); 1960s-1970s, Carlton unpublished, cited by Carlton 1979); Alameda/CA/Ballena Bay, San Francisco Bay (2005, Foss 2009); small marinas, Oakland/CA/Oakland Inner Harbor (2005, Foss 2009); Coast Guard Island/CA/San Francisco Bay (2005, Foss 2009); Coyote Pt Marina/CA/South San Francisco Bay (2005, Foss 2009); Sierra Point Marina/CA/South San Francisco Bay (2005, Foss 2009); San Leandro Marina/CA/San Frncisco Bay (2010, Marrafini et al. 2017)
Vectors
| Level | Vector |
|---|---|
| Alternate | Hull Fouling |
| Alternate | Oyster Accidental |
| Alternate | Ballast Water |
Regional Impacts
| Ecological Impact | Competition | |
| In San Francisco Bay, this tunicate appears to strongly compete with other fouling organisms, both native and introduced (Blum et al. 2007). Fouling community diversity was negatively correlated with C. robusta's abundance, and experimental removal of this tunicate resulted in increased diversity (Blum et al. 2007). | ||
| Ecological Impact | Habitat Change | |
| The tunics of C. robusta provided a poor substrate for settlement of other organisms when this organism dominated fouling plates (Blum et al. 2007). | ||