Search

Chlorine efficacy as a biocide for ballast water treatment was investigated under cold- and warm-water temperatures across winter and summer seasons. Freshwater phytoplankton samples were collected and acclimated under in situ environmental conditions ranging from 2 to 22 [degrees]C. Samples were exposed to seven chlorine treatments (from 0.02 to 5.0 ppm), in addition to a control (0.0 ppm). Free-chlorine concentrations, phytoplankton abundance, and photosynthetic efficiency were measured up to 48 h following treatment. After 4 h of treatment at concentrations less than 0.22 ppm, phytoplankton densities were reduced by more than 50%, without cell resurgence. Similar reduction was recorded immediately after exposure when chlorine concentrations were higher than 3.0 ppm. After 8 h, free chlorine neared 0.0 ppm for initial chlorine concentrations below 1.2 ppm, irrespective of temperature regime. Winter phytoplankton exhibited slightly lower mortality to chlorine exposure regardless of the temperature, although they also exhibited lower photosynthetic efficiency. Despite a general absence of significant effect of temperature on the chlorine decay, our results suggest that higher doses of chlorine or longer exposure times may be required during winter to achieve full treatment effect. Tests at large scales are needed to further confirm these findings. L'efficacite du chlore comme biocide pour le traitement de l'eau de ballast a ete etudiee dans des conditions d'eau chaude et froide, en ete et en hiver. Des echantillons de phytoplancton d'eau douce ont ete preleves et acclimates dans des conditions ambiantes allant de 2 [degrees]C a 22 [degrees]C. Les echantillons ont ete exposes a sept traitements au chlore (de 0,02 ppm a 5,0 ppm), en plus d'un traitement temoin (0,0 ppm). Les concentrations de chlore libre, ainsi que l'abondance et le rendement photosynthetique du phytoplancton ont ete mesures jusqu'a 48 h apres le traitement. Apres 4 h de traitement a des concentrations de moins de 0,22 ppm, les densites de phytoplancton avaient baisse de plus de 50 % sans resurgence de cellules. Une baisse semblable a ete observee immediatement apres l'exposition quand les concentrations de chlore etaient superieures a 3,0 ppm. Apres 8 h, la concentration de chlore libre s'approchait de 0,0 ppm pour des concentrations initiales de chlore inferieures a 1,2 ppm, peu importe le regime thermique. Le phytoplancton hivernal presentait une mortalite legerement plus faible decoulant de l'exposition au chlore, quelle que soit la temperature, mais son rendement photosynthetique etait aussi plus faible. Malgre l'absence generale d'effet significatif de la temperature sur la decomposition du chlore, nos resultats donnent a penser que des doses plus elevees de chlore ou de plus longues durees d'exposition pourraient etre necessaires durant l'hiver pour que le traitement soit pleinement efficace. Des essais a grande echelle sont necessaires pour confirmer ces resultats. [Traduit par la Redaction], Introduction Commercial shipping is one of the primary vectors for the transfer of harmful and nonindigenous species to bays and estuaries worldwide (Hulme 2009). Vessels not fully loaded with cargo [...]

Ships' ballast water and sediments are vectors that contribute to the unintentional spread of aquatic non-native species globally. Ballast water management, as well as commissioning testing of ballast water management systems and compliance monitoring under the regulations of the International Maritime Organization (IMO) aimat minimizing the unwanted spread of organisms. This study compiles data for treated ballast water samples collected and analyzed from 228 ships during 2017-2023. The samples were collected from the ballast discharge line or directly from the ballast tank for enumeration of living organism concentrations in the categories of =50µm and <50 to =10µm -sized organisms, as well as indicator microbes in comparison to the ballast water performance standard of the IMO (Regulation D-2). In addition, several ship-specific factors were examined to infer potential factors affecting compliance rates. Nearly all ships were compliant with the ballast water performance standard for indicatormicrobes and <50 to =10µm -sized organisms, whereas almost half of all samples exceeded the limit of ten viable organisms m-3 for the =50µm -sized organisms. Compliance testing results did not differ significantly between sampling years, indicating that compliance rate did not change through time. The rate of compliance was higher for commissioning testing than compliance testing. Clear ship-or system-specific factors that lead to compliance or non-compliance were not detected, even though type of ballast watermanagement system, filter mesh size associated with the systemand source of ballast water affected compliance significantly either for the samples taken from the discharge line, or ballast tank. As compliance did not improve significantly over time, compliance testing of ships' ballast water should be undertaken to ensure that the systems remain operational after commissioning and ships meet requirements of the D-2 standard. Furthermore, the study outcomes promote further research on the efficiency of filter mesh sizes and different filtration units associated with ballast water management systems, to improve mechanical removal of larger organisms. Finally, as several ships exceeded the compliance limit by hundreds or thousands of living organisms, technological advancements and operational measures may be needed to improve the overall reliability of ballast water management. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We examined the risk of introduction associated with potentially toxic or otherwise harmful algae (HA) or nonindigenous species (NIS) of dinoflagellates in ballast water from 63 commercial ships visiting ports of eastern Canada in 2007-2009. Ship categories included transoceanics undergoing ballast water exchange (BWE) and coastal ships with or without BWE. Of 159 species of dinoflagellates observed in Lugol-preserved samples, 15 were potential HA (six Dinophysis spp.) and 46 were NIS (including three HA). We found at least one species of HA in 81% of all ships examined, and maximum cell concentrations reached nearly 4000 cells x [L.sup.-1]. Coastal nonexchanged tankers carried the greatest cell concentrations of HA. NIS dinoflagellates were found in 56% of ships, significantly more in ships with BWE. There was no evidence that ships with BWE contained significantly fewer taxa or lower concentrations of HA dinoflagellates, indicating that BWE is not efficient in controlling the introduction of these organisms. In fact, BWE promoted the transport of NIS dinoflagellates, possibly because of the wide distribution of several of these species. Coastal ship traffic is a significant introduction pathway for HA (ships with and without BWE) and NIS (ships with BWE) dinoflagellates in eastern Canada. Le risque d'introduction associe a la presence de dinoflagelles potentiellement nuisibles ou toxiques (algues nuisibles, HA) ou especes non-indigenes (NIS) dans l'eau de ballast est examine pour 63 navires commerciaux visitant des ports de l'est du Canada en 2007-2009. Ces navires se repartissent en trois categories : transoceaniques effectuant un echange d'eau de ballast (BWE), navires cotiers avec ou sans BWE. Des 159 differentes especes de dinoflagelles observees, 15 sont HA (dont six Dinophysis spp.) et 46 NIS (incluant trois HA). Au moins une espece de HA se retrouve dans 81 % des navires examines et les concentrations maximales atteignent pres de 4000 cellules x [L.sup.-1]. Les bateaux-citernes cotiers sans BWE montrent les plus fortes concentrations de HA. Les NIS se retrouvent dans 56 % des navires, significativement plus abondantes dans les navires avec BWE. Il n'y a pas d'evidence que les navires avec echange ont des concentrations ou des nombres d'especes HA plus faibles, indiquant l'inefficacite de cette strategie de mitigation. En fait, les echanges de ballast favorisent le transport de dinoflagelles NIS, possiblement a cause de leur large distribution geographique. Le trafic maritime cotier represente une voie significative d' introduction pour les dinoflagelles HA (navires avec et sans BWE) et NIS (navires avec BWE) dans l' est du Canada., Introduction Ship traffic has increased steadily over the last decades, in terms of both ship size and numbers, as well as the frequency of voyages (Bourgeois et al. 2001; Hulme [...]

1. Species invasions depend on the abundance and rate at which organisms are introduced to new localities, known as propagule pressure. Due to the challenges of measuring propagule pressure, proxy variables are often used; however, untested proxy variables may obscure the role of propagule pressure vs. ecological factors that facilitate invasion, leading to uncertainty about the invasion process and confoundingmanagement response. 2. To generate absolute estimates of propagule pressure and facilitate meaningful comparison among pathways of species introduction, we extend proxy variables by combining ecological and global trade data with hierarchical statistical models. We derive absolute propagule pressure with probability distribution functions (propagule size: the probability of introducing n propagules per event; and overall propagule pressure: the probability of introducing n propagules per year) and, based on these projections, evaluate the performance of ballast water volume (m3) as a common proxy variable. 3. Hindcast accuracy of ballast water volume was low but strongly scale-dependent, exhibiting poor accuracy (R2 = 0058) at small scales and onlymarginal accuracy at large scales (overallR2 = 0169).As a result, conclusions about propagule pressure are likely to be biased based on the ballast volume proxy, as may be conclusions about species invasion when ballast water volume has been used. Irrespective of geographic pathway, estimated propagule sizes demonstrated extreme leptokurtosis and long right tails, withmaximum values between 131-fold and 2966-fold greater than median values. These characteristics signify a subset of introduction events involving extreme propagule abundance that may provide opportunity to overcome Allee thresholds or marginal environmental conditions. 4. Developing meaningful propagule supply functions is critical to resolve the role of propagule pressure within the invasion process and test hypotheses about species colonization at landscape scales. By joining absolute propagule pressure with existing theory about species extinction, the expected ecological outcome of environmental policy tomanage propagule pressure can be estimated within a statistical framework. [ABSTRACT FROM AUTHOR]

Understanding the implications of different management strategies is necessary to identify best conservation trajectories for ecosystems exposed to anthropogenic stressors. For example, science-based risk assessments at large scales are needed to understand efficacy of different vector management approaches aimed at preventing biological invasions associated with commercial shipping. We conducted a landscape-scale analysis to examine the relative invasion risk of ballast water discharges among different shipping pathways (e.g., Transoceanic, Coastal or Domestic), ecosystems (e.g., freshwater, brackish and marine), and timescales (annual and per discharge event) under current and future management regimes. The arrival and survival potential of nonindigenous species (NIS) was estimated based on directional shipping networks and their associated propagule pressure, environmental similarity between donor-recipient ecosystems (based on salinity and temperature), and effects of current and future management strategies (i.e., ballast water exchange and treatment to meet proposed international biological discharge standards). Our findings show that current requirements for ballast water exchange effectively reduce invasion risk to freshwater ecosystems but are less protective of marine ecosystems because of greater environmental mismatch between source (oceanic) and recipient (freshwater) ecoregions. Future requirements for ballast water treatment are expected to reduce risk of zooplankton NIS introductions across ecosystem types but are expected to be less effective in reducing risk of phytoplankton NIS. This large-scale risk assessment across heterogeneous ecosystems represents a major step towards understanding the likelihood of invasion in relation to shipping networks, the relative efficacy of different invasion management regimes and seizing opportunities to reduce the ecological and economic implications of biological invasions. [ABSTRACT FROM AUTHOR]

ABSTRACT The abundances and diversity of dinoflagellate cysts (including non-indigenous or harmful species) in ballast sediments were examined for the east and west coasts and the Great Lakes, to assess the potential invasion risk for these organisms and to determine similarity across regions., In total, 147 ships were sampled, distributed among three categories: (1) transoceanic, with mandatory ballast water exchange (BWE); (2) coastal with BWE; and (3) coastal without BWE. Factors that could account for variability in results were examined including ship routes, BWE, ballast water age and sediment volume in ballast tanks., The pattern of potential invasion risk differs according to the region examined. The east coast had greater concentrations of viable cysts per tank, particularly for coastal ships (with a maximum close to 2 × 106 cysts per tank in coastal exchanged ships compared with 1 × 105 for the west coast). When considering viable cysts g-1 dry sediment, maximum concentrations were found in unexchanged coastal ships from the east coast (28 cysts g-1 compared with 5 for the west coast), but these ships contained less sediment, decreasing the overall abundance of cysts per tank. These results are in the lower range of values reported for Scotland or Australia, which reached a maximum of 2.3 × 104 cysts cm−3 of sediment., Ballast water exchange had a different influence according to the region: on the east coast, the invasion risk was reduced by BWE while it had no significant effect in the other two regions. Ballast water age and sediment volume were also different among regions, but they were not clearly related with cyst concentrations in ballast tanks., Future management of ballast sediment should take into consideration these regional differences in order to reduce the introduction of dinoflagellate NIS that threaten the conservation of coastal habitats through reduction of native diversity., Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]