Ecosystems such as the Great Lakes support indigenous bacteria and other tiny organisms that often are critical to the maintenance of the physical, chemical, and biological features of the Great Lakes as we know them. Yet little is known about this invisible biological activity, and little is being done to protect it from damage resulting from human activity. Of urgent interest are the potential effects of introductions of non-native microbes by ships and other vectors into the native microbial community. The Northeast-Midwest Institute, along with several collaborators including Cornell University, Old Dominion University, the Great Lakes Commission, and the University of Minnesota-Duluth received a $1 million grant from the Great Lakes Protection Fund in 2007 to develop tools and processes to probe the sensitivity of the Great Lakes microbial community to newcomers, and to protect it. Federal collaborators include the Western Fisheries Research Center of the U.S. Geological Survey, which has extensive expertise in fish pathogens and their movement globally.

The goal of this integrated research and policy exercise is to generate a practicable approach to assess, detect, and manage the risks to the Great Lakes posed by the introduction and translocation of nonindigenous microbes, particularly human and nonhuman pathogens, by commercial ships and other vectors. The output of the two-year project will be a preliminary risk characterization, development of effective monitoring tools geared at assessing actual microbial threats to the ecosystem, and methods for integrating the tools with current monitoring programs of Great Lakes resource managers.

Regional need

While human travelers are a primary vector of airborne pathogens globally, the ballast water and sediment of commercial vessels are an established vector for the incidental transport of waterborne microbes worldwide. Other vectors could include infected live food and/or packing material. Microbial hitchhikers can comprise human and nonhuman pathogens, as well as other microorganisms that are ecologically significant. Human pathogens are the most commonly cited concern and correspondingly, the subject of much investigatory work in the United States. In particular, Vibrio cholerae have been observed in ballast of ships visiting ports of the Great Lakes, the Gulf of Mexico, and the Chesapeake Bay. Other fecal-indicating organisms and human pathogens detected in studies of ballast water in vessels visiting the Great Lakes-St. Lawrence Seaway system include fecal coliforms, fecal streptococci, Clostridium perfringens, Salmonella spp., E. coli, Cryptosporidium spp., Giardia spp., Encephalitozoon intenstinalis, Pfiesteria piscicida, Aureococcus anophagefferens, and enteroviruses (see Johengen et al., 2005).  Still, little is known about the potential that pathogens transported in ships can actually cause human or wildlife disease, or otherwise harm the environment. Risk factors that would amplify or mitigate threats are also poorly documented. Nonetheless, the issue of human pathogenic microorganisms in ballast water and their potential discharge into receiving systems globally led the International Maritime Organization (IMO) to include discharge standards for Vibrio cholerae, E. coli., and Enterococci in its 2004 convention on ballast water. In the absence of an adequate risk assessment, it remains unclear whether the requirements are meaningful. Even less is known about the threat of nonhuman pathogens that may be translocated globally. Viral Hemorrhagic Septicemia (VHS) virus, a systemic infection of various fish species caused by a rhabdovirus, offers a recent example of a significant pathogen in Great Lakes native fish populations for which transmission elsewhere within and outside the basin poses a serious threat. Another highly pathogenic rhabdovirus that may be emerging in the Great Lakes in the near future is Spring Viremia of Carp Virus (SVCV). SVCV was discovered in freshwater carp in Hamilton, Ontario, in September, 2006. There have been at least five other outbreaks throughout the United States since 2002.

Relevance

There is little doubt that microbial hitchhikers in ships and other vectors threaten the economic and environmental assets of the Great Lakes region. In particular, transportation of harmful microorganisms by ballast water could jeopardize free flow of trade as well as ecosystem services. Currently, however, the threat is poorly understood and the policy response disorganized and ineffective. There is little capacity for accountability, and no proven treatment measures. This integrated research/policy exercise will lead to a road map for eliminating the risk of the establishment of ship-mediated harmful non-native microbes in the Great Lakes ecosystem through practical and effective policies. The integrated research and policy work will achieve this by:

• Describing the nature and extent of the hazard;
• Supplying tools for a system of harbor and ship monitoring; and
• Supplying an institutional system for implementing comprehensive monitoring basin-wide.

As a result of this work, both regulated carriers, ports, and shippers, and federal, state, and local regulators are likely to make informed and practical changes to reduce the liabilities to trade and the Great Lakes posed by microbial stowaways. These changes will likely include effective ballast treatment for newly arrived/arriving harmful organisms.