Ballast Water in Ships Giving Microorganisms a Free Ride

Hordes of microorganisms, including viruses and other germs that may harm people or marine life, sail into U.S. ports from abroad every year in the ballast water that keeps ships stable, according to a team from the Smithsonian Environmental Research Center in Edgewater, Md. The study suggests that microorganisms may pose a greater danger than bigger, known invaders in ballast water, such as mussels.

The researchers tested ballast water from ships that came mainly from Europe and the Mediterranean Sea. They report in today’s Nature that each gallon of ballast water carried an average of 31 billion suspected viruses and 3.5 billion bacteria, including some disease-causing strains of cholera. Other microbes were not identified, but could well include some that harm local marine plants and animals or people.

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Compiled by Times medical writer Thomas H. Maugh II