Aquatic Hitchhikers Ecological Society of America 02.01.01 When ships unload their cargo, they often fill their ballast tanks with water to provide balance for their return journey. In addition to water, many aquatic organisms are sucked into these tanks and given transport. A ship will then empty its ballast tank (and various aquatic stowaways) at the next port it takes on cargo. Many invasive species have become introduced into new areas this way. A relatively simple control mechanism is to exchange ballast water on the high seas between ports to remove invasive species before they reach the destination port. Other methods being explored are using filters to trap organisms as the tanks are filled or heating the water to kill them.  Prepared by the Ecology Society of America   1707 H St., NW Suite 400   Washington, DC 20006   ©2001 The Aurora Collection, Inc. All Rights Reserved. Site Development by: Interactive Multimedia. Inc.