Domestic ballast operations on the Great Lakes: potential importance of Lakers as a vector for introduction and spread of nonindigenous species

Abstract

Ballast water is recognized globally as a major vector of aquatic nonindigenous species (NIS) introductions; domestic ballast water transfers, however, have generally been considered low risk in North America. We characterize ballast operations of domestic ships in the Great Lakes -St. Lawrence River system (Lakers) during 2005-2007 to examine the risk of primary and secondary introductions associated with ballast water transfers over short distances. Results indicate that Lakers transported at least 68 million tonnes of ballast water annually. Approximately 71% of ballast water transfers were interregional, with net movement being from lower to upper lakes. A small proportion of ballast water discharged in the Great Lakes (<1%) originated from ports in the St. Lawrence River that may serve as sources for new NIS. These results indicate that domestic ballast water transfers may contribute to NIS introductions and are likely the most important ballast-mediated pathway of secondary spread within the Great Lakes. Future efforts to reduce invasion impacts should consider both primary and secondary introduction mechanisms.

Range expansion and molecular confirmation of the Asian fish tapeworm in the lower Great Lakes and St. Lawrence River with notes on infections in baitfish

“…Alternatively, its disjunct distribution between the Great Lakes and St. Lawrence River may be attributed to movement of infected fish or copepods in ballast water from domestic shipping within the Great Lakes-St. Lawrence basin. Although the majority of ballast water in the Great Lakes-St. Lawrence River basin is moved in a predominantly upstream direction by the domestic fleet (Rup et al, 2010), between 2005 and 2007, 1.7% of the ship trips (54 events) that loaded ballast at ports within Lake Ontario and Lake Erie (including ports in the Huron-Erie corridor) subsequently released their ballast to Valleyfield, QC (upstream of St. Lawrence River detections), and Montreal, QC (downstream of detections; Drake et al, 2015). The direct movement of fishes via ballast occurs relatively infrequently, while the movement of invertebrates is more common (Wonham et al, 2000).…”

Swarms of the Ponto-Caspian mysid Hemimysis anomala in Montreal Harbour, St. Lawrence River, Canada

“…Open all year-round, Montreal Harbour is a multipurpose port with vessel traffic of 2000 ships per year and a total volume of 30 million metric tons of containerized cargo as well as breakbulk, dry and liquid bulk cargo. Resulting from domestic and international ship activities, the Montreal Harbour is subject to a high ballast water movement (Rup et al, 2010), thereby facilitating the spread of nonindigenous species (de Lafontaine and Costan, 2002). Water depth varies between 11 and 14 m. Due to local hydrography and seasonal variation in river discharge, harbor waters are a mix of low conductivity waters originating from the Ottawa River flowing along the north shore of the river and of high conductivity waters from Lake Ontario in the center channel and along the south shore (Hudon et al, 2010).…”

Invertebrates and their dormant eggs transported in ballast sediments of ships arriving to the Canadian coasts and the Laurentian Great Lakes

“…As eggs buried in sediment are possibly protected from saltwater exposure during ballast management activities (Bailey et al 2006;Briski et al 2010), this vector may be more important than the transport of active invertebrates in water. In addition, ballast water studies have typically focused on transoceanic ships while neglecting intracoastal ship traffic (Rup et al 2010). It is possible that intracoastal shipping could represent an important vector depending on the proportion of total ship traffic that it represents (Rup et al 2010; 71% in the Great Lakes).…”

“…In addition, ballast water studies have typically focused on transoceanic ships while neglecting intracoastal ship traffic (Rup et al 2010). It is possible that intracoastal shipping could represent an important vector depending on the proportion of total ship traffic that it represents (Rup et al 2010; 71% in the Great Lakes). Many intracoastal ship transits are exempt from mandatory flushing and exchange regulations on the presumption that movement of ballast water is occurring only within a single marine ecoregion and thus is viewed as nonrisky (Government of Canada 2006;SLSDC 2008).…”

“…Many intracoastal ship transits are exempt from mandatory flushing and exchange regulations on the presumption that movement of ballast water is occurring only within a single marine ecoregion and thus is viewed as nonrisky (Government of Canada 2006;SLSDC 2008). This assumption may not be valid if NIS established in one part of the region are transferred in ballast water to another location in the ecoregion where the NIS is not present (Rup et al 2010). Such intracoastal transfers could be particularly effective at introducing NIS since these voyages typically are of relatively short duration, with relatively high survivorship of NIS in ballast tanks in consequence (Humphrey 2008).…”