BALLAST ON BOARD' DOESN'T MEAN 'NO ORGANISMS ON BOARD'
May 10, 2005 — While carrying goods and raw materials to the Great Lakes, international ships, even though fully loaded with cargo and not carrying pumpable ballast water (no ballast on board or "NOBOB"), still carry aquatic species that can be released into the lakes, according to a report by NOAA and the University of Michigan. (Click NOAA image for larger view of zebra mussels, called the “poster child” for aquatic invasive species because their invasion of the Great Lakes in the late 1980s led to major policy initiatives at the national level in the United States. Click here for high resolution version, which is a large file. Please credit “NOAA.”)
"We have a responsibility to protect the Great Lakes, which are major economic and recreational assets," said Tim Keeney, deputy assistant secretary of commerce for oceans and atmosphere and NOAA's leader for aquatic invasive species. "This report more thoroughly and systematically identifies what is coming into the Great Lakes in ballast tanks that are considered empty."
Lead authors of the report, Thomas Johengen of the University of Michigan and David Reid of the NOAA Great Lakes Environmental Research Laboratory, worked with scientists from the University of Windsor (Canada), Old Dominion University and the Smithsonian Institution, as well as a Canadian ship operations expert.
The team surveyed 103 NOBOB vessel crews about their management practices and boarded 42 of those vessels to enter and sample residual water and sediment in 82 ballast tanks. NOBOB ships are loaded to capacity with cargo and carry no declarable ballast water on board. However, once they unload their cargo, they take on Great Lakes water for stability. If they then load cargo at another Great Lakes port, they must discharge the ballast water, which now is a mix of Great Lakes water and residual foreign water and sediment and the organisms therein.
"It is the discharge of this mixed ballast water that leads to the potential introduction of additional non-indigenous species to the Great Lakes,” said Johengen.
About 90 percent of the saltwater ships entering the Great Lakes are NOBOB vessels and are not covered by the ballast water exchange regulations implemented in 1993 by the U.S. Coast Guard. The exchange system requires ships to replace pumpable ballast water at sea with open-ocean water, which reduces the number of organisms available for discharge and exposes them to "salinity shock," possibly causing death or an inability to reproduce.
"A diverse group of phytoplankton (small, floating plant life) and invertebrate biota (eggs, larvae) was found in the residual unpumpable ballast water and sediments, including dozens of non-indigenous species not reported in the Great Lakes," said Reid, who is the director of the NOAA Aquatic Invasive Species Research Center in Ann Arbor, Mich. "The results of our microbial, phytoplankton and invertebrate analyses confirm that NOBOB vessels are vectors for non-indigenous species introductions to the Great Lakes Basin."
Other findings of the study include an improvement in ballast management practices over the past 20 years by the shipping industry, a need for further assessment to determine if the microbial pathogens pose a human health risk and the evidence that saltwater flushing seems to decrease the number of organisms and the accumulation of sediment.
The study also concluded that, when performed, ballast water exchange "can be highly effective for reducing the concentration of organisms entrained with coastal ballast water," but that "potential benefits to the Great Lakes attributed to 'salinity shock' should be regarded with caution," because of the wide range of salinity tolerances found in nature.
"This is a complex problem, and our study provides a more comprehensive scientific basis for considering new policies and for identifying possible preventive measures and treatments," Reid said.
Johengen added that, "While there is pressure to take immediate action, it will require the cooperation of regulatory agencies, the scientific community, the shipping industry and the public to identify the best solutions."
The Great Lakes NOBOB Assessment and Ballast Water Exchange Study was a $1.9 million, three-year effort funded by the Great Lakes Protection Fund, NOAA, the U.S. Environmental Protection Agency and the U.S. Coast Guard.
NOAA, an agency of the U.S. Department of Commerce, is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nation's coastal and marine resources.
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