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MacIsaac, H.J., R.I. Colautti, A.J. Niimi, C.D.A. van Overdijk, E.L. Mills, and K. Holeck, 2001. Spatial and Temporal Analysis of Transoceanic Shipping Vectors to the Great Lakes, University of Windsor. Proceedings of the Second International Conference on Marine Bioinvasions, New Orleans, La., April 9-11, 2001, p. 92. Spatial and Temporal Analysis of Transoceanic Shipping Vectors to the Great LakesThe Great Lakes of North America have been invaded and profoundly affected by introduction of nonindigenous species (NIS). Release of ballast water by transoceanic commercial ships has been the strongest vector of NIS to the Great Lakes during the 20th century. Here we review spatial and temporal patterns of ballast release by foreign, transoceanic ships entering the Great Lakes system with saline ballast water [ballast onboard (BOB) ships] and those that enter the system with cargo but which load and subsequently discharge ballast water within the lake system [no ballast onboard (NOBOB) ships]. Even though a large percentage (79.5%) of in-bound ships stop at ports on Lake Ontario or Lake Erie as their first port-of-call, a disproportionate percentage of ships (52%) discharge saline ballast water into Lake Superior. Similarly, a disproportionate fraction (49%) of NOBOB ships discharge freshwater ballast water into Lake Superior. Putative sources of recently established NIS in the Great Lakes are generally consistent with major ports (Antwerp, Rotterdam) and regions (lower Rhine, Baltic Sea) from whence much Great Lakes ship traffic originates. Although actual 'propagule pressure' cannot be quantified at present, the pattern of ballast water discharge by BOB and NOBOB vessels in the Great Lakes indicates that Lake Superior should be particularly vulnerable to ballast water-mediated invasions by NIS. Contact: Hugh MacIsaac, Great Lakes Institute for Environmental Research,
University of Windsor, London Life Centre, Windsor, ON N9B 3P4, CANADA |