ACCELERATING INVASION RATE IN A HIGHLY INVADED ESTUARY

Biological invasions are a major global environmental and economic pro blem. Analysis of the San Francisco Bay and Delta ecosystem revealed a large number of exotic species that dominate many habitats in terms o f number of species, number of individuals and biomass, and a high and accelerating rate of invasion. These factors suggest that this may be the most invaded estuary in the world. Possible causes include a larg e number and variety of transport vectors, a depauperate native biota, and extensive natural and anthropogenic disturbance.