Ballast water deoxygenation can prevent aquatic introductions while reducing ship corrosion

One of the most important mechanisms for the introduction of aquatic nuisance species is transport in ship ballast waters Although several ballast tank treatments to prevent transport of aquatic organisms appear promising, all existing approaches will result in significant costs to the shipping industry. This study describes a treatment that can dramatically reduce the survivorship of most organisms found in ballast waters while providing economic benefits to ship owners. Purging of oxygen from ballast tanks with nitrogen was recently found to be a cost-effective technique for reducing corrosion and therefore extending ship life We tested the tolerance of larvae of known invasive invertebrate species to low levels of oxygen, comparable with those resulting from the anticorrosion treatment, and detected significant levels of mortality. Two separate literature reviews further support the conclusion that few organisms will be able to withstand extended periods of exposure to nitrogen-treated ballast water. This novel deoxygenation technique may therefore have direct benefits to both marine conservation and the shipping industry (C) 2001 Elsevier Science Ltd. All rights reserved.