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MP8 Control and Regulation of Non-indigenous Species
() Ballast water treatment strategies: evaluation of efficacy and post-treatment environmental concerns.
Stubblefield, W1, Gensemer, R1, Cooper, W2, Ruiz, G3, 1 Parametrix, Inc., Corvallis, OR, USA2 University of North Carolina-Wilmington, Wilmington, NC, USA3 Smithsonian Environmental Research Center, Edgewater, MD, USA
ABSTRACT- The worldwide transfer and introduction of non-indigenous species (NIS) by human activities is having significant and unwanted ecological and economic impacts on coastal marine ecosystems. The global movement of ballast water on ocean vessels now appears to be the single largest transfer mechanism responsible for NIS invasions in marine systems. Currently the National Invasive Species Act of 1996 requests that vessels voluntarily conduct open-ocean exchange of ballast water, or use an approved alternate treatment, prior to discharge in U.S. ports. Ballast water exchange (BWE) is a process by which coastal ballast water is discharged in the open ocean, and replaced with open ocean water theoretically free from nuisance NIS. However, BWE has some significant limitations-it is not always possible to safely conduct an exchange in rough seas and may leave a residual of coastal organisms. Research efforts are now underway to develop and implement technological alternatives to BWE. Although many alternatives are being explored, their evaluation is at an early stage, and no alternative treatments have received regulatory approval. In addition to physical treatment approaches being considered as alternatives to BWE, e.g., filtration, UV light, there are a number of chemical biocides under consideration, e.g., chlorine, ozone, metadione. Two principal concerns exist with any proposed treatment technology: 1) Does the proposed technology represent an improvement over the current standard /benchmark, i.e., BWE; and 2) What are the potential environmental consequences of the discharge of post-treatment ballast water? An empirical approach as been developed, and will be discussed, to address the question of treatment efficacy assessment. Similarly, an ecological risk-based approach has been developed to address post-treatment discharge concerns.
Key words: ballast water, invasive species, non-indigenous species
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