Invasion
Invasion Description
1st Record: CA/Coyote Creek (1941, Leidy 2007); 1st Watershed Record: CA/Sacramento-San Joaquin watershed (1922, Cohen and Carlton 1995; Dill and Cordone 1997)
Geographic Extent
CA/Sacramento-San Joaquin Delta (1922, Cohen and Carlton 1995; Dill and Cordone 1997); CA/Suisun Marsh (Matern and Moyle 2002); Oakland/Lake Merritt (1965, Cohen and Carlton 1995; Dill and Cordone 1997); 'Collection records during the 1940s for Estuary streams include Green Valley Creek (1940), Coyote Creek (1941), Walnut Creek (1942), Marsh Creek (1945), and Novato Creek (1945) (Leidy, 1984)' (Leidy 2007)
Vectors
| Level | Vector |
|---|---|
| Probable | Biocontrol |
Regional Impacts
| Ecological Impact | Competition | |
| In experiments in ponds in San Joaquin County, the presence of Western Mosquitofish (Gambusia affinis) and introduced Bullfrogs (Lithobates catebianus both adversely affected tadpoles of the native Red-Legged Frog (Rana aurora draytonii). Gambusia affinis did not reduce numbers of tadpoles, but did cause injuries and reduced growth of the tadpole, probably reducing recruitment. Bullfrogs were much more effective as predators (Lawler et al. 1999). | ||
| Economic Impact | Health | |
Western Mosquitofish (Gambusia affinis) were introduced to San Francisco Bay for perceived benefits of mosquito control (Cohenn and Carlton 1995; Dill and Cordone 1997) | ||