Invasion
Invasion Description
1st Record: CA/Newport Bay (1955, Carlton 1979)
Geographic Extent
CA/Colorado Lagoon-Alamitos Bay (Reish 1968, cited by Carlton 1979; 2000, Cohen et al. 2002; Burnaford et al. 2011); CA/Anaheim Bay (1972, Reish et al. 1975, cited by Carlton 1979); Bolsa Chica Lagoon (1992, Carlton 1992); CA/Newport Bay (1955, Carlton 1979); Catalina Island/CA/Avalon Harbor (2011, California Department of Fish and Wildlife 2014, establishment unknown); Baja California Norte/Mexico/Estero de Punta Banda (early 1980s, Torchin et al. 2005)
Vectors
| Level | Vector |
|---|---|
| Alternate | Ballast Water |
| Alternate | Hull Fouling |
Regional Impacts
| Ecological Impact | Habitat Change | |
| High densities of G. demissa in Estero de Punta Banda, Baja California Norte, Mexico, appear to facilitate growth of the native Pacific cordgrass Spartina foliosa. They also present a hazard to the endangered Light-footed Clapper Rail (Rallus longirostrus levipes), in Estero Puerto Bando, based on the damage seen to the subspecies (R. l. oboletus) in San Francisco Bay (Torchin et al. 2005). | ||
| Ecological Impact | Competition | |
| Based on the very high biomass seen in Estero de Punta Banda (4 X that of the next most abundant and native species, Tagelus spp.), competition for phytoplankton and other suspended food particles is likely (Torchin et al. 2005). | ||