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Article paru dans Watertown Daily Times : Some invasive species may be undetected: more new species wouldn't necessarily mean ballast effort was a failure
Le 28 mai 2008
MONTREAL - Newly mandated saltwater flushing and subsequent inspections of cargo vessels' ballast water tanks hold considerable promise for keeping new invasive species out of the Great Lakes. But these measures represent only a start.
"The new regulations will be an important step in negating invasive species, but not a final solution," said William Nash, director general of Maritime Safety at Transport Canada. "There's been some major progress made."
Those researching the problem realize that although ballast flushing is "highly effective," it may not kill all invaders. Indeed, there may be invasive species in the Great Lakes that are yet to be discovered.
Hugh MacIsaac, a research scientist at the Great Lakes Institute for Environment Research at the University of Windsor in Ontario, said that a population of millions or even billions of certain organisms may have to be present before they can be detected. And because many of them reproduce asexually, even a single organism could multiply and spread throughout the region.
"If you see a report (on new invasive species) six months or a year from now, that doesn't mean the policy isn't working," Mr. MacIsaac said. He said what would bother him is if in 10 years there are reports of new invaders that could only have reached the Great Lakes via ballast water.
"If that's the case, then we'd have to go back and reassess our standards to see if they're strict enough," Mr. MacIsaac said. "This isn't intended to be the end of the line."
Many scientists studying the problem believe technology can provide the means to treat ballast water for invasive species while it is still onboard a vessel, a development that would likely relegate ballast water flushing to a backup procedure.
One possibility is adding a highly concentrated brine solution to the ballast tanks, rather than flushing them at sea.
"We've been exploring the use of very high salinity brines, basically sodium chloride at two to three times the concentration of ocean water," said David F. Reid, a physical scientist with the National Oceanic and Atmospheric Administration. "Not very many things can live in brine."
Mr. Reid said results to date indicate that when organisms that are able to survive the mid-ocean saltwater exchange are exposed to brine, most of them die very quickly. Such a treatment regime could be used as a backup on vessels that for design reasons cannot perform a saltwater flushing of their ballast tanks, he said.
Other onboard treatment systems also are in the works.
Fednav Ltd., which operates almost 100 cargo vessels, is Canada's largest dry-bulk shipping group. In recent years, the company has outfitted two of its vessels with prototype ballast treatment systems.
"The first prototype system that we tested in 2001 involved a copper ion generator, an active biocide," said John T. Stubbs, Fednav's manager of technical services. "While it was found to have a degree of effectiveness, from the standpoint of the discharging of water after, there were environmental issues - putting an active biocide in the water."
In 2005, the company tried again, this time installing a Norwegian system called "Ocean Saver" on the M/V Federal Welland, sister ship to the M/V Federal Kivalina, which participated in a demonstration ballast water inspection May 5 in Montreal. Mr. Stubbs said there are three phases to the testing process - laboratory, proof of concept and vessel installation. The system on the Federal Welland is "somewhere between phases 2 and 3 right now," he said.
"The concept is being proven and tested on land," Mr. Stubbs said. "The prototype systems are going to be built in the next few months for installing on vessels currently in service. There are many challenges; the biggest one, of course, is being able to treat the water at the volume that the ships are pumping."
Federal Welland's two ballast pumps each can discharge water at the rate of 700 tons per hour. "You've got to find a system that's able to work at that pumping capacity," Mr. Stubbs said. Testing should be completed next year.
Before onboard treatment systems can enter practical use, regulations must be developed to guide further system development. The U.S. Coast Guard is working to create regulations that harmonize with those now in force in Canada, as well as those under consideration by the International Maritime Organization.
"Our regulation will set a standard and a schedule for vessels to comply, show what types of vessels will need to comply, and will take into account systems in use in other countries," said Bivan Patnaik, the Coast Guard's regulatory coordinator. He said both Coast Guard's draft environmental impact statement and its draft regulation are under review by the federal Department of Homeland Security, while its economic analysis will be submitted shortly. Mr. Patnaik could not provide a timetable as to when the proposed regulation might be approved.
Ballast water is not the only means by which non-native invaders can enter an ecosystem. Other vectors include agricultural runoff, accidental release of fishing bait and the aquarium trade. But controlling ballast water remains crucial.
"Pragmatically, you must focus on the most important vector first," Mr. MacIsaac said. "No matter how you slice it, ballast water is it."
In the end, invasive species have done some damage that cannot be reversed.
Mr. MacIsaac said invasive species have "transformed the way our lakes work - Lake Erie, Lake St. Clair, Lake Michigan are all vastly different from what they used to be like. But the appropriate people have stepped up to the plate."
