Exotic species threat to California's coastal resources

The potential scale and impact of biological invasions in coastal waters is demonstrated by invasions in the San Francisco Bay/Delta Estuary. Biodiversity, ecosystem processes and human activities have already been substantially affected, while new organisms continue to be introduced into the ecosystem. Protecting coastal biodiversity, and preventing new impacts on the human use of coastal resources, will require regulation of the various mechanisms by which exotic marine and freshwater organisms are transported across oceans and continents to California. The broad scope of the problem is known, as are some of the steps needed to reduce the rate of transport and invasion. The most critical vector now operating is undoubtedly the transport of organisms in ships' ballast water. To reduce the flood of invasions into California's coastal waters, there is an urgent need for the adoption and implementation of clear legal requirements for the high-seas exchange of ballast water.