Great Lakes Ballast-Water Microbes Report Features Research by Dobbs

October 03, 2013

Fred Dobbs

Fred Dobbs, an Old Dominion University faculty member who is an expert in the ecology of microorganisms, is one of the researchers behind a new report that urges a more proactive monitoring regime to keep ships' ballast water from spreading potentially dangerous microbes in the Great Lakes.

The report was written for the Northeast-Midwest Institute (NEMWI), which is one of the sponsors, together with the Great Lakes Protection Fund, of a multiyear project to study the need for a cost-effective early detection monitoring system for ship-borne harmful microbes in the Great Lakes.

Dobbs, who has been researching the microbial ecology of ships' ballast water for nearly two decades, worked on the project together with scientists from Cornell University, the University of Minnesota, the U.S. Geological Survey and NEMWI.

Their report, "Harmful Microbes in Ballast Water: Protecting the Great Lakes Ecosystem," was published online Oct. 1 in the institute's Weekly Update at NEMW.org.

The report concludes that early detection and monitoring of microbes in ballast water is warranted; useful to all stakeholders, including ship owners; and feasible.

"This just-released NEMWI report represents an approach to harmful environmental microorganisms that is more strategic and comprehensive than any I've seen before," said Dobbs, who is a professor in ODU's Department of Ocean, Earth and Atmospheric Sciences. He also lauded his colleagues. "I worked with first-rate researchers from several institutions, all of us focused on this Great Lakes issue, and our scientific efforts were effectively translated by NEMWI into language understandable to managers and regulators."

Dangers listed by the researchers include pathogens such as a form of Viral Hemorrhagic septicemia virus (VHSV) that began causing major fish kills in the lower Great Lakes in 2005. The report also states that microbiological factors - together with chemical factors - can heighten rates of corrosion of steel structures in the Great Lakes.

The researchers note up front that ships are not the only carriers of microbes around the Great Lakes. Wind can spread them; so can humans and animals. Still, they say the threat of ballast water conveyance of dangerous microbes is serious enough to warrant increased monitoring of ships. In addition to moving the microbes between ports or lakes, the ballast tanks can serve as incubators, according to the report.

Monitoring techniques used currently usually involve tests done on the tissue of dead fish to identify organisms that may have killed them. "The conventional approach to monitoring for fish diseases is to record visible fish kills," the report states. "Arguably, this post mortem approach serves the purposes of forensics at best; clinical signs of disease like fish kills occur long after infectious levels of pathogens are in play...." If detection were earlier, the report says, resource managers and industry could "proactively and efficiently attenuate spread and mitigate damage."

The researchers propose new molecular tests that can be done on fish tissue, as well as on water samples - whether they be from the lakes or ballast tanks - that are quick and cheap. These tests, according to the report, "can process much greater sample volume per unit time than conventional methods, and can target a wide range of problem microbes."

Although random sampling of a vast network of harbor sites in the Great Lakes is not possible, the researchers say, "sampling can yield rich and novel information on harmful microbe distribution if sampling sites are carefully selected to target possible occurrences, whether or not clinical signs of infection are present."

As for tests of ballast water, the report suggests the use of a ship discharge monitoring system that was developed as part of the Great Ships Initiative by NEMWI project team members and several other partners. The monitoring system, which would cost about $50,000 per ship, has been successfully tested in the Great Lakes.

The NEMWI Weekly Update introduction to the report said the work of the researchers "not only protects the ecological resources of the Great Lakes, but also safeguards the region's water transport system, water supply network and recreational fishery."

A seminal article written by Dobbs about microbial stowaways in ships' ballast tanks appeared in 2008 in the journal Microbiology Today, which is based in England and has an international readership. He was recruited by the publication to write the article for a themed issue titled "Bugs Get Everywhere."

In the article, Dobbs described 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. He noted 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, he wrote. 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 wrote.