Invasion
Invasion Description
1st Record: Alameda County/CA/San Francisco Bay (1874, Newcomb 1874, as Mya hemphilli, cited by Carlton 1979). From 1999 through 2005, bivalve biomass, including M. arenaria, decreased by 2 orders of magnitude. This was attributed to a cold phase of the El Nino-La Nina oscillation, with increased upwelling and decreased sea-surface temperatures, favoring native cold-water predators, such as shrimp Crangon spp., juvenile Dungeness crab (Metacarcinus magister), and English Sole (Parophrys vetulus), resulting in increased predation, decreased bivalve biomass and grazing, and resulting blooms of phytoplankton (Cloern et al. 2007).
Geographic Extent
Alameda County/CA/San Francisco Bay (1874, Newcomb 1874, 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/Suisun Bay (Cohen and Carlton 1995); CA/Grizzly Bay (Peterson and Vayssieres 2010, abundant in dry years, pre Corbula invasion); CA/South San Francisco Bay (Cohen and Carlton 1995); Palo Alto/CA/South San Francisco Bay (1974, Nichols and Thompson 1985b); Brisbane/CA/Brisbane Lagoon, South San Francisco Bay (Cohen et al. 2005); China Camp/San Pablo Bay (Robinson et al. 2005); Fruitvale Bridge, Oakland/CA/Oakland Estuary (Cohen et al. 2005); San Leandro Marina//CA/San Francisco Bay (2010, Marrafini et al. 2017)
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). | ||
| 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 in 1976-1977, 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). | ||