Dynamics and short-term survival of toxic cyanobacteria species in ballast water from NOBOB vessels transiting the Great Lakes—implications for HAB invasions Martina A. Doblin a,d, * , Kathryn J. Coyne b , Johanna M. Rinta-Kanto c , Steven W. Wilhelm c , Fred C. Dobbs a a Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, VA 23529, USA b Graduate College of Marine Studies, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA c Department of Microbiology, The University of Tennessee, Knoxville, TE 37996, USA d Institute for Water and Environmental Resource Management/Department of Environmental Sciences, University of Technology, Sydney, P.O. Box 123, NSW 2007, Australia Received 21 February 2006; received in revised form 16 May 2006; accepted 22 May 2006 Abstract We measured the presence, viability and potential toxicity of cyanobacteria in ships’ ballast tanks during three domestic voyages through the North American Great Lakes. Using molecular methods, the toxin-producing forms of Microcystis and Anabaena were monitored in ballast water after ships’ ballast tanks were filled at their first port of call, and at subsequent ports as ships transited the Great Lakes. Microcystis was detected in ballast water at intermediate and final ports of call in all three experiments, but the presence of Anabaena was more variable, suggesting low abundance or patchy distribution in ballast tanks. Both species were detected in ballast water up to 11 days old. Detection of the microcystin synthetase gene, mcyE, in ballast tanks indicated entrained cells were capable of producing microcystin, and further analyses of RNA indicated the toxin was being expressed by Microcystis, even after 11 days in dark transit. These data demonstrate within-basin transport and delivery of planktonic harmful algal bloom (HAB) species to distant ports in the world’s largest freshwater reservoir, with potential implications for drinking water quality. These implications are discussed with respect to management of microbial invasions and the fate of introduced phytoplankton in their receiving environment. # 2007 Elsevier B.V. All rights reserved. Keywords: Ballast-water; Molecular probes; Viability; Toxic cyanobacteria 1. Introduction Phytoplankton are prominent amongst the taxa transported globally in ships’ ballast water (Galil and Hu ¨lsmann, 1997; Gollasch et al., 1998; McCarthy and Crowder, 2000). Of these phytoplankton, harmful algal bloom (HAB) species comprise a variable proportion of ballast populations (0 to 1.4  10 4 cells l 1 in ships with exchanged and unexchanged ballast water; Zhang and Dickman, 1999) and are of particular concern because of their risk to food production, aquatic foodwebs and human health (Shumway and Cembella, 1993; Scholin et al., 2000; Carmichael, 2001). Numerous steps are involved in successful invasion of organisms carried in ships’ ballast water. A species www.elsevier.com/locate/hal Harmful Algae 6 (2007) 519–530 * Corresponding author. Tel.: +61 2 9514 8307; fax: +61 2 9514 4079. E-mail address: martina.doblin@uts.edu.au (M.A. Doblin). 1568-9883/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.hal.2006.05.007