A Comprehensive Analysis of Ship-mediated Invasion Risk in the Canadian Arctic

Ballast water discharge and hull fouling are significant transport vectors of aquatic non-indigenous species (ANS) globally. The introduction of ANS by ship vectors has been identified as an activity that may negatively impact the Canadian Arctic ecosystem, but there has been no scientific evaluation of the current level of risk. In addition, climate change may increase the risk of ANS introductions to the arctic region because melting of the polar ice cap will allow increased vessel access to arctic waters. ANS also may experience increased natural dispersal. In addition to these changes in dispersal of ANS to the Arctic, climate change may also enhance the probability of establishment for some ANS.

We will present the first analysis of ship-mediated invasion risk in the Canadian Arctic based on ship traffic and environmental matching between donor and recipient ports. We summarized 2005–2008 shipping data from the Canadian Coast Guard's Information System on Marine Navigation and Transport Canada's Ballast Water Database, and use vessel arrivals and ballast water discharge volume as proxy measures for propagule pressure. Our results show that Iqaluit, Churchill and Deception Bay appear to be at highest risk because they receive a disproportionate number of vessel arrivals and/or ballast discharges originating from coastal and foreign ports. Iqaluit had the greatest number of annual vessel arrivals (44 ± 2 S.E.M) of all ports; Churchill received the greatest annual volume (142,322 m3 ± 17,296) of ballast water discharge and the second largest annual number of vessel arrivals (35 ± 4 S.E.M.); Deception Bay received 20 (± 5 S.E.M.) vessel arrivals and 15,984 m3 (± 12,382 S.E.M.) of ballast water discharge annually.

We refined risk by comparing temperature and salinity between potential source and recipient ports to determine the likelihood of ANS establishment post-introduction. For ANS introduction via ballast water discharge, Port Alfred appears to be a potential donor of ANS to Churchill because of high propagule pressure (i.e. ship traffic) and environmental similarity between the two ports. Similarly, Lower Cove is a potential source of ANS for Deception Bay. The results of this study will provide important baseline information about the relative level of invasion risk at arctic ports, and will be used to determine sampling sites for biological assessment of ballast water and hull fouling biota in subsequent studies.