Invasion

Invasion Description

1st Record: San Rafael/CA/San Pablo Bay (1987, McDonald and Koehn 1988; McDonald et al. 1991). The actual invasion date is unknown. This species was first detected in molecular surveys, begun in 1985 (McDonald et al. 1991). This bioregion is a hybrid zone for Mytilus galloprovincialis and M. trossulus. Since molecular studies began in the late 1980s and early 1990s, both species and hybrids have coexisted but have varied in abundance with changes and gradients of salinity and temperature, with M. galloprovincialis prevailing at higher salinities and higher temperatures, while M. trossulus predominated at lower salinities, and at lower temperatures. These interactions were complex, so that M. trossulus outnumbered M. galloprovincialis at low salinity sites in San Francisco Bay, even though these sites had higher temperatures (Braby and Somero 2006).

Geographic Extent

San Rafael/CA/San Pablo Bay (1987, McDonald and Koehn 1988; McDonald et al. 1991, molecular survey); Benicia/CA/Carquinez Straits (1990, Sarver and Foltz 1993, molecular survey);