A variety of life forms can be found in ship's ballast water, depending on the seasonal and temporal variations of the ballast source water. Commonly found organisms fall into three general groups: plankton, microbes, and macrofauna. There are two types of plankton measured in ballast water: zooplankton and phytoplankton.

MIRL and our collaborators have identified and enumerated plankton samples from the ballast water of over 200 ships. Current projects focus on identifying and measuring the survivorship of these organisms during transport and in some studies assessing survival after ballast discharge through lab-based experiments. Geographic areas of specific interest include Chesapeake Bay, San Francisco Bay, Prince William Sound and the Great Lakes and Baltic regions. Understanding what is being transported in ballast is an important first step in preventing or limiting invasions and their spread.

Current projects assessing ballast water biota:

•  West Coast Dispersal of Invasive Species in Domestic Ballast Water (Sea Grant)

•  Characterization of Aquatic Non-Indigenous Species for the Department of Defense (Office of Naval Research)

•  Assessment of Transoceanic No Ballast Onboard Vessels and Low Salinity Ballast Waters as Vectors for Invasive Species to the Great Lakes-collaborator (Great Lakes Protection Fund)

In addition to plankton research, MIRL and its collaborators have measured microorganism communities in the ballast water of over 75 vessels entering Chesapeake Bay from foreign ports. A large focus of our research is the detection of Vibrio cholerae O1 and O139 (causative agents of human cholera), since many vessels have been found to contain toxic or non-toxic strains of this species. The data collected shows that microorganisms are extremely abundant in ballast, frequently measuring concentrations of 10⁸ bacteria per liter of water and 10⁹ virus like particles per liter of water. Our findings suggest that transfer of ballast may play an important role in the global distribution of microorganisms and in the epidemiology of some waterborne diseases.

MIRL has conducted two studies on ballast water microbiology

•  Measuring the transfer, dynamics, and risk of invasion for microbial communities associated with ballast water (1998-2000, Sea Grant)

•  Presence, dynamics, and fate of pathogenic microorganisms in ballast water and ballast water microcosms (2000-2002, Sea Grant)