The movement of ballast water by commercial shipping is a prominent pathway for aquatic invasions. Ships' ballast water management is now transitioning from open ocean exchange to a ballast water performance standard that will effectively require use of onboard treatment systems. Neither strategy is perfect, therefore, combined use of ballast water exchange plus treatment has been suggested to provide greatest protection of aquatic ecosystems. This study compared the performance of exchange plus treatment against treatment alone by modeling establishment rates of nonindigenous zooplankton introduced by ballast water across different habitat types (fresh, brackish, and marine) in Canada. Treatment was modeled under two efficacy scenarios (100% and 50% of ship trips) to consider the possibility that treatment may not always be successful. The model results indicate that exchange plus treatment will be more effective than treatment alone at reducing establishments when recipient ports are freshwater (58 140 vs 11 338 trips until ≥1 establishment occurs, respectively). Exchange plus treatment also serves as an important backup strategy if treatment systems are partially effective (50% of trips), primarily for freshwater recipient ecosystems (1442 versus 585 trips until ≥1 establishment occurs, respectively).

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Ship biofouling is a major vector for the introduction and spread of harmful marine species globally; however, its importance in Arctic coastal ecosystems is understudied. The objective of this study was to provide insight regarding the extent of biofouling (i.e., percent cover, abundance, and species richness) on commercial ships operating in the Canadian Arctic. A questionnaire was used to collect information on travel history, antifouling practices, and self-reported estimates of biofouling extent from ships operating in the region during 2015–2016. Twenty-five percent of ships operating in the region during the study period completed the questionnaire (n = 50). Regression trees were developed to infer the percent cover of biofouling, total abundance of fouling invertebrates, and fouling species richness on respondent ships based on previous underwater wetted surface assessments of commercial ships in Canada. Age of antifouling coating system was the only significant predictor of percent cover and total abundance of biofouling invertebrates, while the number of biogeographic realms previously visited and port residence time were significant predictors for fouling species richness. Comparison of relevant travel history features reported through the questionnaire to the regression tree models revealed that 41.9% of 43 respondent ships had antifouling coating systems older than 630 days and are therefore inferred to have relatively high (> 9.3%) biofouling percent cover. More than half of respondent ships (62.8%) had antifouling coating systems older than 354 days and are therefore inferred to have a relatively high total abundance (over 6,500 individuals) of fouling invertebrates. Nearly half of respondent ships (45.9% of 37 ships) had visited at least three biogeographic realms during their last 10 ports-of-call and are therefore inferred to have relatively high fouling species richness (mean 42 taxa). Self-reported estimates of biofouling cover were unreliable, being much lower than model inferences. Although the regression tree models have relatively low predictive power, explaining only 15–33% of the variance in biofouling extent, this study indicates that commercial ships are an active pathway for the transportation of non-indigenous aquatic species to Canadian Arctic coastal ecosystems via biofouling.

A number of ballast water compliance monitoring devices (CMDs) have been made commercially available to verify the efficacy of ballast water management systems by quantifying the living organisms for both plankton size classes (≥50 μm and ≥10–<50 μm). This study aimed to examine whether new CMDs can provide a reliable indication of compliance regarding Regulation D-2 and to evaluate their performance for indicative analysis of organisms by assessing their accuracy (comparison to microscopy) and precision (comparison within measurement). Challenge fresh water samples were collected in four locations of Lake Ontario, Canada, whereas marine challenge water samples were collected around the Bay of Fundy, New Brunswick, Canada. Ballast water samples were collected from ships visiting several ports across Canada. Overall, accuracy was higher (>80%) in estimating organisms from prepared-challenge water (Ballast Eye and BallastWISE) than from ballast water samples (>70%) (B-QUA only). The sensitivity ranged from 50 to 100% for the ≥50 μm organism size class, whereas for the ≥10–<50 μm organism size class, it was higher for freshwater samples (>75%) than for marine samples (>50%). The performance of CMDs should be assessed under real-world conditions for a better understanding and to improve their use.