Oyster-Mediated Molluscan Invasions
The historic, large-scale movement of the eastern oyster (Crassostrea virginica) from the mid-Atlantic coast to San Francisco Bay provides a rare opportunity to quantitatively analyze the phenomena of marine biological invasions. For most invasion vectors it is impossible to reconstruct what organisms were brought from where and when (e.g., the worldwide movement of planktonic life stages in ballast water).
In contrast, the commercial introduction of the eastern oyster to the Pacific coast of the United States is a more distinct series of events. Since the vector, source region, and recipient region are known, quantitative analyses were possible using a well-defined species pool. Using characteristics of biogeography, life history, and habitat of mid-Atlantic coast molluscan oyster-associate fauna, it was possible to discriminate statistically between successful and failed invaders.
Landings from important mid-Atlantic oyster grounds. The vast majority of live oysters that were shipped west by rail originated in vincinities of New York City.
Discriminant analysis separates San Francisco Bay invaders, successful invaders of other areas, and failed invaders according to historical abundance and tolerance of low salinity.