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.
We 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.
In addition to plankton research, we 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.
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