Invasive species entering U.S. waters (aquatic nuisance species, or ANS) exact tremendous economic losses, social, recreational, and ecological disturbances and costs. National attention was drawn to the invasive species problem with the arrival of zebra mussels in the Great Lakes in the late 1980s. Since then, virtually all coastal and Great Lakes states have experienced ecological change and loss from zebra mussels and other aquatic nuisance species. Ballast water has been identified as a major pathway for introduction of ANS. Ships use large amounts of ballast water to stabilize the vessel during transport. Ballast water is often taken on in the coastal waters in one region after ships discharge wastewater or unload cargo, and then discharged at the next port of call, wherever more cargo is loaded, which reduces the need for compensating ballast. Thus, the practice of taking on and discharging ballast water is essential to the proper functioning of ships, because the water that is taken in or discharged compensates for changes in the ships weight as cargo is loaded or unloaded, and as fuel and supplies are consumed. However, ballast water discharge typically contains a variety of biological materials, including non-native, nuisance, exotic species that can alter aquatic ecosystems.


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    Title :

    Regulating Ballast Water Discharges: Current Legislative Issues. CRS Report for Congress


    Contributors:
    C. Copeland (author)

    Publication date :

    2008


    Size :

    14 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English