Dobbs Article about Microorganisms in Ballast Water Appears in Magazine

An article written by Old Dominion University faculty member Fred Dobbs about microbial stowaways in ships' ballast tanks appears in the May issue of the magazine Microbiology Today, which is based in England and has an international readership.

Dobbs, a professor in the Department of Ocean, Earth and Atmospheric Sciences at ODU, is an expert in the ecology of microorganisms that can be found in ships' ballast water. He was recruited by Microbiology Today to write the article for a themed issue titled "Bugs Get Everywhere."

In the feature-length article, Dobbs describes his research and that of other scientists concerning the goings and comings of tiny organisms that are taken onto ships in ballast water at one location in the world and pumped out at another location.

"Are we playing Johnny Appleseed with aquatic microorganisms as global shipping inadvertently spreads them around the world in discharged ballast water?" he asks in the article. "And if so, need we be concerned that some of those microbes are harmful?"

Dobbs notes the well-documented cases in which ballast tank discharges have transferred larger organisms from their indigenous region to new regions where they thrive without control by predators or parasites. Zebra mussels from Eastern Europe, for example, have been relocated to the Great Lakes and elsewhere in North America, where they reproduce rapidly, adversely affect the food chain for native aquatic creatures, foul the hulls of boats and clog pipes in water-treatment and industrial water-cooling systems.

But the case is not so clear for invasive microbial species. Some scientists argue that these very tiny organisms already are distributed worldwide, so ballast discharges cannot introduce new species. Other scientists have produced examples of aquatic microbes having a specific biogeography. "If the second group of scientists is correct, then aquatic microorganisms can be nonindigenous, are therefore potentially invasive, and their presence in ballast water is indeed of concern," Dobbs writes.

Although most aquatic microorganisms are not harmful to humans, some species such as Vibrio cholerae, the etiologic agent of human cholera, and the dinoflagellates that cause red tides could pose threats, according to Dobbs.

Individual states in the United States have enacted regulations to try to strictly limit the number of bacteria and viruses that might be in ballast water discharges, and the International Maritime Organization is proposing similar microbiological mandates. Dobbs explains, however, that current technologies that can be utilized by ships-ranging from chemical treatments of ballast water to filtration and ultraviolet radiation-are hard-pressed to meet the needs of shippers as well as the expectations of regulators.

The Dobbs article is illustrated by micrographs of phytoplankton taken by Lisa Drake, a former graduate student of the author who became a research professor at ODU before joining the faculty of the U.S. Coast Guard Academy. She and Dobbs continue to collaborate on research projects.