Non-natives Essay

SF Bay Non-Natives

            Discharging ballast water in the San Francisco Bay has caused many non - native species to move into the San Francisco Bay. Many non – native species stick under the ballast ships or are in the water discharged by the ballast ships. Some of the alien species transferred from foreign countries to the San Francisco Bay are algae, sponges, worms, mollusks, crustaceans, and fish. Some scientists believe that a new species joins the San Francisco Bay about every three months due to mainly the ballast ships. The San Francisco Bay has the most non – native species in the entire world. Scientists think that the San Francisco Bay will be overpopulated with non- native species which will cause native species to become extinct because of competition and diseases.

            The main reason non - native species have been introduced to the San Francisco Bay is by ballast ships, but some other ways also exist. People have deliberately brought plants and flowers by traveling through ships in the San Francisco Bay which has also brought many non – native species. Plants such as Eriogonum were brought deliberately. Eriogonum attracts many insects by its nectar flow and pollen. This affects native bees because bees collect pollen, as well as nectar. This makes Eriogonum extremely attractive for bees, which makes it easy for bees to collect food. This heavily decreases the competition for food among the bee populations. This increases the population of bees by a great amount. Then, the bees become overpopulated resulting to the food chain altering.

            Most non – native organisms have little to no impact, but green crabs are one exception. Green crabs’ scientific name is Carcinus maenas, and they are natives of Europe. Many are non – native in the San Francisco Bay by the discharge of ballast water. Green crabs were introduced in the 1960s. They eat on clams and Dungeness crabs. Dungeness crabs provide commercial seafood operations in the region. When the Dungeness crabs’ population decreases because of green crabs, organisms cannot get commercial seafood operations. Commercial seafood operations are getting closer to extinction. No evidence has been shown trying to remove green crabs. The practice of ballast water is still being used which will bring more green crabs and other non – native species.

Works Cited

Caldwell, Jeffrey. "Native Bee Garden Notes, San Francisco Bay Area." Jefferycaldwell.blogspot. 13 Jan. 2005. 10 Sept. 2008 <http://jeffreycaldwell.blogspot.com/2005/01/native-bee-garden-notes-san-francisco.html>.

"Green Crab." SGNIS. Smithsonian Environmental Research Center. 14 Sept. 2008 <http://www.sgnis.org/www/green_crab.htm>.

Lampe, Paul D. "Volunteers and local federal agencies eradicate non-native algae." Inside Bay Area. 9 July 2008. UC Davis. 13 Sept. 2008 <http://www.insidebayarea.com/oaklandtribune/ci_9812427>.

"Nature Gallery." Introduced Species. Pacific Island Travel. 10 Sept. 2008 <http://www.pacificislandtravel.com/nature_gallery/introducedspecies.html>.

Zaitlin, Jody. "Stopping the Flow: Ballast Water and Invasive Species." Bay Area Monitor. Mar.-Apr. 2000. San Francisco Estuary Institute. 13 Sept. 2008 <http://www.bayareamonitor.org/mar00/ballastwater.html>.