Invasion
Invasion Description
1st record: Alameda County/CA/San Francisco Bay (1874, Newcomb 1874, as Mya hemphilli, cited by Carlton 1979)
Geographic Extent
CA/Eel River (Weymouth 1920, cited by Carlton 1979); CA/Big River (Weymouth 1920, cited by Carlton 1979); CA/Navarro River (Weymouth 1920, cited by Carlton 1979); Bodega Bay/CA/Bodega Harbor (1916, Packard 1918, cited by Carlton 1979; Standing 1975, cited by Carlton 1979); CA/Estero del Americano (1919, Weymouth 1920, cited by Carlton 1979); CA/Tomales Bay (Clark 1916 , cited by Carlton 1979); CA/Abbotts Lagoon (1919, Weymouth 1920, cited by Carlton 1979); CA/Estero de San Antonio (Magee 1941, cited by Carlton 1979); CA/Drakes Estero (1919, Weymouth 1920, cited by Carlton 1979); CA/Bolinas Lagoon (1922, Bonnot 1940, cited by Carlton 1979); Alameda County/CA/San Francisco Bay (1874, Newcomb 1974, as Mya hemphilli, cited by Carlton 1874); Collinsville/CA/Sacramento-San Joaquin Delta (Cohen and Carlton 1995); Sherman Island/CA/Sacramento-San Joaquin Island (Hopkins 1986); CA/Grizzly Bay (Peterson and Vayssieres 2010, abundant in dry years, pre Corbula invasion); CA/Suisun Bay (Cohen and Carlton 1995); CA/South San Franicsco Bay (Cohen and Carlton 1995); Brisbane/CA/Brisbane Lagoon, South San Francisco Bay (Cohen et al. 2005); Fruitvale Bridge, Oakland/CA/Oakland Estuary (Cohen et al. 2005); Santa Cruz/CA/Monterey Bay (1881, Stearns 1881, cited by Carlton 1979, failed stocking); Watsonville/CA/Old Salinas River Channel (pre-1911, Carlton 1979); Monterey/CA/Monterey Bay = Elkhorn Slough (Dall 1916; Dall 1921, cited by Carlton 1929); CA/Elkhorn Slough (1927, MacGinitie 1935, cited by Carlton 1979; not seen in decades, locally extinct, Wasson 2001); CA/Morro Bay (1915, failed planting of 2000 clams, Heath 1916, cited by Carlton 1979)
Vectors
| Level | Vector |
|---|---|
| Probable | Oyster Accidental |
Regional Impacts
| Economic Impact | Fisheries | |
| By the 1880s, M. arenaria supported a commercial fishery of 500-900 tons per year in San Francisco Bay, but this declined to 100 tons per year by 1916 to 1926, and ended after 1948, due to overharvesting, pollution, and possible preference for Venerupis phillipinarum (Japanese Littleneck). However, recreational harvests continue to the present (Cohen and Carlton 1995). Extensive plantings were carried out along the California coast by individuals and the California Department of Fish and Game (Weymouth 1920; Bonnot 1940, both cited by Carlton 1979). Recreational clamming probably occurs in many other estuaries where clams are common. | ||
| Ecological Impact | Competition | |
| Mya arenaria may have replaced Macoma nasuta in clam beds in San Francisco Bay (Cohen and Carlton 1995). | ||
| Ecological Impact | Herbivory | |
| Mya arenaria, when abundant, has had significant impact as a filter-feeder. During periods of high salinity, it has been one of several filter-feeders contributing to low phytoplankton biomass in Suisun Bay (Nichols and Thompson 1985a). | ||
| Ecological Impact | Food/Prey | |
| Mya arenaria is an important prey organism for ducks, shorebirds, flounders, skates, rays, and native crabs and shrimps (Carlton 1979; Cloern et al. 2007). | ||
| Ecological Impact | Trophic Cascade | |
| During a drought in 1976-1977 in Suisun Bay, a high abundance of Mya arenaria and other marine filter-feeders may have contributed to a low phytoplankton abundance, which in turn contributed to low zooplankton abundance and a scarcity of the omnivorous Neomysis mercedis, an important food for juvenile fishes. This, in turn, may have led to decreased recruitment of Morone saxatilis (Striped Bass), an economically important introduced gamefish (Nichols and Thompson 1985b; Cohen and Carlton 1995). | ||