Ballast water

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Ballast Water

Ballast water is water carried by cargo ships to maintain balance. It is also one of the major routes for non-native or invasive Species to reach the Great Lakes. Invasive species stow away in ballast tanks, and when ships dump in U.S. waters, they can sometimes pump out the stowaways as well. More than 70,000,000 tons of ballast water are dumped in U.S. waters annually.

Andrew Solow, a professor at Woods Hole in Cape Cod and member of the U.S. Coast Guard, spoke at a Michigan State University conference on Invasive Species in October, 20007. He spoke on the unfortunate lack of information about the rate at which new species can be introduced through ballast water.

"There are a lot of factors involved, and it's almost impossible to study ballast water exchange in detail," Solow said. "It's a problem of physical bounds. Nobody wants to lift a huge cargo ship out of the water to see what drains out."

Solow introduced this table on amount of species that can stow away in ballast tanks per year and potentially be introduced into the U.S. PCM stands Per Cubic Meter.

Cells left-aligned, table centered

Filter Method	# of Fauna
No Action	2,000,000
Ocean Exchange	200,000
10 PCM	12,000
1 PCM	1,200
0.1 PCM	120
Statistical Calculation

Over 150 species of marine organisms are known to have been introduced by ballast water, including Zebra Mussels, Sea Lamprey and the Round Goby. While some appear benign, others have become pests, threatening biodiversity, fisheries and clogging ecosystems. Some introduced species severely deplete native populations or deprive them of food. Others form colonies which can smother existing animals. Introduced toxic dinoflagellates cause red tides and algal blooms that can affect or even kill shellfish, fish, sea birds and humans.

Unfortunately, there is little experimental data on the trends of ballast water exchange. There is also no data on the parameters a population of invasive species needs to become permanent. A study in 1999 found that when ballast water was pumped out, an average of 12 large animals, living and dead, went with it.

"We don't know how many of one species it takes to set up a new population," Solow said. "Or how small a population needs to be to die out. And no one has anything on the rate at which homosexually reproducing taxa could aggregate either. There's a lot we don't know."

Great Lakes Ballast Water Resolution

- "A resolution calling for federal legislation to protect the Great Lakes and St. Lawrence River from ballast water discharges of invasive species was unanimously adopted at the 2007 Semiannual Meeting of the Great Lakes Commission, May 14-15 in Indianapolis. The resolution urges the Great Lakes Congressional Delegation to make passage of legislation that reduces and ultimately eliminates the introduction and spread of AIS from ballast water its top Great Lakes priority in 2007. Among its other provisions, it calls for an immediate requirement that all ships currently exempt from regulation, due to No Ballast on Board (NOBOB) status, be required to treat residual ballast water by best management practices such as ballast water exchange. It also calls for an ultimate ballast water treatment goal of zero discharge of viable organisms and a requirement to meet an environmentally protective standard within five years following enactment."
Check out the resolution and the Great Lakes Commission

Study on Ballast Water Exchange in the Great Lakes and Chesapeake Bay.[PDF]