Nonindigenous aquatic species have established a presence in many freshwater and marine ports around the world, and some of these are nuisance species which cause ecological and economic problems in their new environment Well-known examples include the introduction of the zebra mussel into the Great Lakes and the Asian clam into San Francisco Bay
The purpose of the pilot study was to assess the risk of invasion of Prince William Sound by nonindigenous species as a result of the discharge of tanker ballast water. The study clarified that such discharge does in fact pose a risk. The ballast water of large ships is known to be the chief method of transport of nonindigenous species from one region to another. However extensive study has not been done to see if this pattern exists in far northern climates.
Ballast water is pumped into tankers as oil is discharged at refineries to maintain the weight and stability of ships when they make return trips to Alaska. The ballast water is then discharged when oil is loaded at the Valdez Marine Terminal. If the ballast water is carried in the same tanks that hold oil it is discharged to the terminals Ballast Water Treatment Facility to be cleaned of oily residue. If the water was shipped in a segregated tank without coming Into contact with oil, it is discharged directly into the water.
During testing this spring Smithsonian researchers found that large quantities of plankton are transported in the segregated ballast water tanks of arriving tankers. The initial study did not conduct extensive sampling of the waters in Prince William Sound. Therefore researchers were not able to assess the degree of risk posed by the presence of nonindigenous species.
An additional two-year study now under way will expand the ballast water analysis to include more ships arriving from a variety of ports during all seasons. The stuldy will further analyze and identify the species in the ballast water to determine if they can live long enough to become established in the sound, and, if they are present whether they pose an environmental risk. Researchers aIso will sample the waters of Prince, William Sound to determine what nonindigenous species are present.
For further information contact:
Joel Kopp, Project Manager for Prince William Sound RCAC, 907-835-1940 Gary Sonnevil, Project Leader for U.S. Fish & Wildlife Service, 907-262-9863
-FWS-
