Invasion
Invasion Description
1st record: CA/north San Francisco Bay (1957, Newman 1963)
Geographic Extent
CA/north San Francisco Bay (1957, Newman 1963); Berkeley Aquatic Park/CA/San Francisco Bay (1958, Newman 1963); Oakland/CA/Lake Merritt (1961, Newman 1963); China Camp/CA/San Pablo Bay (1959, Newman 1963); Marin County/CA/Corte Madera Creek, San Pablo Bay (1960, Newman 1963); China Camp/CA/San Pablo Bay (2005, Robinson et al. 2011); Rodeo/CA/San Pablo Bay (1960, Newman 1963); CA/Montezuma Slough, Suisun Bay (1961, Newman 1963); Antioch/CA/Sacramento-San Joaquin Delta (1961, Newman 1963; Siegfried et al. 1980); John F. Kennedy Park, Napa/CA/Napa River (1993, Cohen and Carlton 1995); Petaluma/CA/Petaluma River (1993, Cohen and Carlton 1995); Palo Alto/CA/Palo Alto Yacht Harbor (1962, Newman 1963); CA/South Francisco Bay (2012-2013, Jimenez et al. 2017, common on hard and soft substrates); CA/Elkhorn Slough (1981, Standing 1981, cited by Wasson et al. 2001); CA/Morro Bay (2000, Power Plant report- http://www.morro-bay.ca.us/mbpp2.pdf; Fairey et al. 2002)
Vectors
| Level | Vector |
|---|---|
| Probable | Ballast Water |
Regional Impacts
| Ecological Impact | Competition | |
| In San Francisco Bay, differences in habitat preference between the native shrimps Crangon spp. and P. macrodactylus may minimize competition (Newman 1963). However, both species feed on the mysid Neomysis mercedis, and could compete for food, particularly in the fall, when N. mercedis numbers are low (Sitts and Knight 1979). Neomysis mercedis is now rare in the San Fracisco estuary, largely replaced by a smaller biomass of Asian mysids. We have no information on how these changes have affected interactions between P. macrodactylus and native Crangon spp. | ||
| Ecological Impact | Predation | |
| The most frequent food item for both P. macrodactylus and Crangon franciscorum in San Francisco Bay was the mysid Neomysis mercedis. In 1976, C. franciscorum consumed up to 6.2% of the mysid biomass, while P. macrodactylus consumed up to 4.8% (Sitts and Knight 1979). Predation on N. mercedis is significant, because this mysid is also an important food source for planktivorous adult and juvenile fish. However, this mysid is now scarce in the San Francisco estuary, largely replaced by smaller species of Asian mysids, as part of a reorganization of the food web caused by the invasion of the Asian Brackish-Water Clam (Corbula amurensis). These changes have probably altered the diet of P. macrodactylus, but we have found no recent diet studies on this shrimp. | ||