The University Record, March 25, 1998

Ships' ballast brings unwelcome critters to Great Lakes

By Peggy Britt
Michigan Sea Grant

Only recently have researchers realized that ballast water (water stored in the hulls of ocean-going ships) is the primary transport for harmful invaders that are settling in the Great Lakes. Ships release and take up this water as they travel from port to port, spreading organisms to new habitats where they can become unwanted residents.

Researchers from Michigan Sea Grant and the University are trying to combat these invaders by developing methods to prevent the release of such exotic organisms into the Great Lakes. Preliminary findings indicate that dispensing a small amount of an environmentally benign chemical, glutaraldehyde, into ballast water may help eliminate these invading species.

A $300,000 grant from the Great Lakes Fishery Trust will enable the researchers to field test the effectiveness and costs of this new treatment approach.

"This is an extremely important investigation into this overlooked option for preventing the introduction of exotic species into the Great Lakes," says Russell Moll, Michigan Sea Grant director and principal investigator.

"We are hopeful that the results of this study will provide resource managers with a safe and effective new tool for stopping the spread of unwanted aquatic organisms," says Moll, who is also an associate research scientist at the Center for Great Lakes and Aquatic Sciences and at the School of Natural Resources and Environment.

One reason researchers are excited about the potential use of glutaraldehyde is that only small amounts are necessary for it to be effective and it degrades quickly into nontoxic naturally-occurring compounds, such as carbon dioxide.

The researchers expect the results of their study to provide resource managers with an important tool for stopping the spread of unwanted aquatic organisms. Their efforts will assist global efforts to stem the tide of exotic species introductions through ballast water.

Moll says a continuous stream of exotic species has invaded the Great Lakes over the past 200 years. Several species have posed a serious threat to native fish aquatic populations and have had a significant economic impact. Sea lampreys caused a tremendous decrease in fish populations, especially lake trout, after they entered the Great Lakes in the 1930s and the 1940s, Moll notes. Zebra mussels have created a major economic impact as well. Expenditures by power plants and industrial facilities to control zebra mussel infestations average well over $10 million a year, he says.

Michigan Sea Grant is a joint program of the U-M and Michigan State University. It is part of a national network of 29 university-based programs of research, outreach and education dedicated to the protection and sustainable use of the United States' coastal and Great Lakes resources.