Excerpt from U.S. Coast Guard “Proceedings of the Marine Safety & Security Council” magazine by LCDR Brian Moore, U.S. Coast Guard Office of Environmental Standards.
The accelerating problem of invasive species in U.S. marine ecosystems is driven largely by changes in shipping practices and increases in traffic volume over the last decades. In the past, most species’ translocation occurred when people purposely introduced organisms they wished to establish in a new location, or when the occasional “hitchhiker” species clung to the hull of a ship to make its way to a new location.
More recently, single-purpose ships such as crude oil carriers now routinely sail to one port with cargo and return to the loading port in ballast, carrying millions of gallons of water each ballast voyage and repeatedly innoculating the waters in the loading port with water from the cargo offloading port. This can reinforce colonies of species that may have been deposited on previous voyages. This repeat depositing of millions of gallons of aquatic organism-carrying water is the perfect design for establishing viable colonies of nonindigenous species in new locations.
As shipping practices evolve and trade increases, such ship-mediated invasions put additional areas at risk for similar ecological and economic impact.
What’s Being Done?
International, national, state, and local efforts have been initiated to address the problem of ballast water-facilitated species translocation.
To facilitate the invention of new systems to address organisms in ships’ ballast water, the U.S. Coast Guard developed the Shipboard Technology Evaluation Program (STEP) to provide an incentive for ship owners to participate in experimental evaluations of promising technologies on operational cargo vessels.
The STEP Process
Under STEP, successful applicants receive an “equivalency,” whereby the Coast Guard deems that use of the experimental system satisfies ballast water management requirements. Enrollment includes a rigorous evaluation of the prototype’s likelihood of success based on a thorough review of the science and engineering behind the technology.
Following this review, the applicant’s study plan is peer-reviewed for scientific rigor and validity. Finally, the Coast Guard completes a thorough evaluation of the potential environmental impact associated with the use of the system. Only upon completion of these screening measures are systems accepted and allowed to begin in U.S. waters.
Technologies Under Evaluation
Current applicants have proposed mechanical filtration systems that expose organisms to ultraviolet energy, use of in situ-generated chlorine ions, and dosing ballast water with chlorine dioxide for sterilization.
Additional technologies that are being advanced include using ultrasonic energy to disrupt cellular structures, heat to sterilize the water, various chemicals as biocides, and de-oxygenation to suffocate any organisms.
As these ballast water treatment efforts mature, a future focus will include dealing with organisms that attach themselves to ships’ hulls, shafts, and anchors, a process that also transports species outside their native range.
For more information:
Full article and “Environmental Protection” edition of USCG Proceedings is available at http://www.uscg.mil/proceedings/Winter2008-09/.
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Direct requests for print copies of this edition to: HQS-DG-NMCProceedings@uscg.mil.
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