Combining ballast water exchange and treatment to maximize prevention of species introductions to freshwater ecosystems

The most effective way to manage species transfers is to prevent their introduction via vector regulation. Soon, international ships will be required to meet numeric ballast discharge standards using ballast water treatment (BWT) systems, and ballast water exchange (BWE), currently required by several countries, will be phased out. However, there are concerns that BWT systems may not function reliably in fresh and/or turbid water. A land-based evaluation of simulated ‘BWE plus BWT’ versus ‘BWT alone’ demonstrated potential benefits of combining BWE with BWT for protection of freshwater ecosystems. We conducted ship-based testing to compare the efficacy of ‘BWE plus BWT’ versus ‘BWT alone’ on voyages starting with freshwater ballast. We tested the hypotheses that there is an additional effect of ‘BWE plus BWT’ compared to ‘BWT alone’ on the reduction of plankton, and that taxa remaining after ‘BWE plus BWT’ will be marine (low risk for establishment at freshwater recipient ports). Our study found that BWE has significant additional effect on the reduction of plankton, and this effect increases with initial abundance. As per expectations, ‘BWT alone’ tanks contained higher risk freshwater or euryhaline taxa at discharge, while ‘BWE plus BWT’ tanks contained mostly lower risk marine taxa unlikely to survive in recipient freshwater ecosystems

Adventures and Misfortunes in Macondo: Rehabilitation of the Cienaga Grande

We describe trajectories of selected ecological indicators used as performance measures to evaluate the success of a mangrove rehabilitation project in the Ciénaga Grande de Santa Marta (CGSM) Delta-Lagoon complex, Colombia, as result of freshwater diversions initiated in 1995. There is a significant reduction in soil and water column salinity in all sampling stations following the hydraulic reconnection of the Clarín and Aguas Negras channels to the Magdalena River. Soil intersticial water salinity (depth: 0.5 m) (7 stations) and water column salinity (0.5 m) (10 stations) values declined significantly (soil \u3c30 g kg-1; water \u3c10 g kg-1) from 1994 to 2000. During 1994 soil interstitial water salinity ranged from 40 g kg-1 (Rinconada) to 100 g kg-1 (KM 13), while water column salinity fluctuated between 25-35 g kg-1 for most of the sampling stations. This salinity reduction increased mangrove forest regeneration promoting a net gain of 99 km2 from 1995 to 1999. The high precipitation recorded in 1995 and 1999 caused by El Niño-La Niña (ENSO), coinciding with the channels rehabilitation, influenced rapid mangrove regeneration. The lack of economic investment in the maintenance of the diversion structures from 2001 to 2004 caused a salinity increase affecting negatively already restored vegetation. A sustainable effort from the international community and the Colombian government is needed to maintain the strategic social and economic benefits reached until 2000 in the CGSM region

Introduction de dinoflagellés non indigènes dans les écosystèmes aquatiques canadiens via les réservoirs de ballast des navires

RÉSUMÉ : L'introduction d'espèces non indigènes de dinoflagellés via le transport maritime représente un risque pour les écosystèmes marins et d'eaux douces du Canada, autant du point de vue de leur biodiversité que de l'économie du pays (e.g. la problématique de la moule zébrée dans les Grands Lacs). Ailleurs dans le monde, des études récentes ont mis en lumière l'influence de vecteurs tels que l'eau et les sédiments de ballast, les routes utilisées par les navires ainsi que les méthodes d 'échange d'eau de ballast sur les introductions d'espèces non indigènes. Au Canada, le Réseau de recherche du CRNSG Canadian Aquatic Invasive Species Network (CAISN) en partenariat avec Pêches et Océans Canada et Transport Canada fut mis sur pied en 2006 pour explorer les principaux vecteurs de transport des organismes envahissants et les facteurs influençant leur succès d'établissement afin de développer des modèles de risques pour les eaux canadiennes. Dans le cadre de ce réseau, le but du présent travail est de mieux comprendre le rôle des vecteurs, les patrons d'invasion selon la région et l'influence des différentes méthodes d 'échange de l'eau de ballast, dans l'introduction des espèces non indigènes incluant les espèces nuisibles ou toxiques de dinoflagellés au Canada. Cette thèse se concentre sur la présence d'espèces non indigènes de dinoflagellés dans l'eau (formes végétatives) et les sédiments (formes de résistance) de ballast des navires commerciaux qu i visitent les côtes est et ouest du Canada et la région des Grands Lacs. De plus, elle fait le lien avec les facteurs antérieurement nommés ainsi que la durée des voyages et le volume d'eau et de sédiments dans les réservoirs à l'anivée des navires. Le corps de la thèse comporte trois chapitres dont les objectifs, méthodes et principaux résultats sont soulignés dans les lignes qui suivent. L'objectif du premier chapitre est d'examiner la présence et l'abondance des espèces non indigènes et nuisibles ou toxiques de dinoflagellés dans les sédiments des navires visitant la côte est du Canada. L'étude se concentre plus spécifiquement sur l'influence des échanges d'eau de ballast, le type de navire et l'âge de l'eau sur la présence de kystes de dinoflagellés non indigènes. Les échantillons de sédiment proviennent de 65 navires et les espèces de kystes de dinoflagellés contenues ont été dénombrées à l'aide d'un microscope inversé. Les résultats confirment la présence de kystes de dinoflagellés non indigènes dans les sédiments de ballast. De plus, certains d'entre eux ont été observés avec du contenu cellulaire (donc potentiellement viables) et des abondances importantes, notamment dans les navires en provenance du nord de la côte est des États-Unis qui, selon la législation canadienne en cours, ne sont pas obligés de faire un échange d'eau de ballast. Ce chapitre a été publié dans la revue Aquatic Invasions. L'objectif du deuxième chapitre est de comparer l'introduction de kystes de dinoflagellés d'espèces non indigènes et nuisibles dans les sédiments de ballast des navires qui visitent la côte est, la côte ouest et les Grands Lacs du Canada. L'étude examine plus précisément l'abondance et la diversité des kystes de dinoflagellés en relation avec les facteurs qui expliquent la variabilité des patrons d'invasion selon la région étudiée, tels que les routes utilisées par les navires, les types d'échanges d'eau de ballast, l'âge de l'eau et la quantité de sédiments contenue dans les réservoirs de ballast. Un total de 147 navires ont été visités pendant trois campagnes d'échantillonnage au cours des étés 2007-2008-2009. L'étude montre que le patron d'invasion change d'une région à l'autre. Sur la côte est, l'échange de l'eau de ballast diminue l'abondance des espèces de kystes de dinoflagellés non indigènes, tandis que sur la côte ouest et les Grands Lacs, les catégories de navires présentent le même risque d'invasion. Ce chapitre a été soumis à la revue Aquatic Conservation: Marine and Freshwater Ecosystems. Alors que les deux premiers chapitres s'intéressent aux organismes présents dans les sédiments des réservoirs de ballast, le troisième chapitre examine la pression d'invasion par les espèces de dinoflagellés non indigènes présentes dans l'eau de ballast des navires visitant les côtes est et ouest du Canada. Le dénombrement et l'identification des formes végétatives de dinoflagellés ont été faits par microscopie inversée. Dans certains cas, des techniques de coloration de cellules ont été réalisées afin de confirmer l'identification des cellules . L'étude met en évidence la contribution des routes transocéaniques et côtières en terme de pression d'invasion (actuelle et effective) des cellules de dinoflagellés non indigènes pour les écosystèmes marins canadiens. L'étude montre que les cellules végétatives de dinoflagellés peuvent survivre aux voyages dans les navires, influençant la pression effective des dinoflagellés non indigènes, et met en perspective les abondances de dinoflagellés déchargés par réservoir et par navire selon le trafic maritime annuel. Ce chapitre sera bientôt soumis à la revue Marine Pollution Bulletin. -- Mots clés: Dinoflagellés, introduction d'espèces non-indigènes, eaux de ballast, sédiments de ballast, pression de propagule. -- ABSTRACT : Introduction of non-indigenous species of dinoflagellates via shipping transport involves a risk to marine and freshwater ecosystems of Canada, in terms of biodiversity and economy (e.g., invasion of the Zebra mussel in the Great Lakes). Elsewhere, recent studies have highlighted the influence of vectors su ch as ballast water and sediments, routes and methods of ballast water ex change in the introduction of non-indigenous species . In Canada, the NSERC-funded research network entitled Canadian Aquatic invasive Species Network (CAISN) was established in 2006 in collaboration with the Department of Fisheries and Oceans Canada (DFO) and Transport Canada, in order to examine the main vectors in the transport of invasive species as weil as the factors influencing the success of establishment of non-indigenous species and to develop risk models for Canadian waters. As part of this Network, the purpose of the present study is to better understand the role of vectors , the invasion patterns according to the region and the influence of different methods of ballast water exchange, in the introduction of non-indigenous species in Canada, incIuding harmful and toxic dinoflagellates. This thesis focuses on the presence of non-indigenous species of dinoflagellates in the ballast water (motile forms) and sediments (resistance forms) of commercial ships visiting the East and the West coasts of Canada and the Great Lakes region. Additionally, this study links the factors previously cited with the duration of the voyages and the volume of ballast water and sediments present in the tanks when ships arrive at their destination port in Canada. The body of the thesis has three chapters with their objectives, methods, results and conclusions. The main results of the present work are outlined in the following paragraphs. The objective of the first chapter is to examine the presence and abundance of nonindigenous and harmful or toxic species of dinoflagellates in the sediments of ships visiting the East coast of Canada. The study focuses specifically on the influence of the ballast water exchange, ship type and ballast water age on the presence of non-indigenous dinoflagellate cysts. Sediment samples were collected from 65 ships and dinoflagellate cyst species present were counted using an inverted microscope. The results confirm the presence of non-indigenous dinoflagellate cysts in ballast sediments. In addition, sorne nonindigenous dinoflagellate cysts were observed with cell content (potentially viable) and high abundance, especially in ships from the northern part of the East coast of the United States, which under Canadian legislation, are not required to exchange their ballast water. This chapter was published in the journal Aquatic Invasions. The objective of the second chapter is to compare the introduction of nonindigenous and harmful species of dinoflagellate cysts in ballast sediments of ships that visit the East and West coasts and the Great Lakes of Canada. The study examines more precisely the abundance and diversity of dinoflagellate cysts in relation to the factors that could explain the variability of invasion patterns according to the area studied, such as routes used by ships , types of ballast water exchange, age of ballast water and the amount of sediments contained in the ballast tanks. A total of 147 ships were sampled during three campaigns in the summers of 2007-2008-2009 . The study shows that the invasion patterns change from one coast to the other. On the East coast, the ballast water exchange reduces the abundance of non-indigenous species of dinoflagellate cysts, while on the West coast and the Great Lakes, aIl the categories of ships pose the same risk of invasion. This chapter was submitted to the journal Aquatic conservation: Freshwater and Marine Ecosystems. While the first two chapters focus on organisms contained in the ballast sediments, the third chapter examines the pressure of invasion by non-indigenous species of dinoflagellates present in the ballast water of ships visiting the East and the West coast of Canada. Motile cells of dinoflagellates were counted and identified with an inverted microscope. In sorne cases, staining techniques were performed on cells to confirm the species identification. The study highlights the contribution of coastal and transoceanic ro utes in terms of invasion pressure (actual and effective) of non-indigenous dinoflagellates in Canadian marine ecosystems. The study shows that motile cells of dinoflagellates can survive ship-borne voyages influencing the effective pressure of non-indigenous dinoflagellates. It also asses ses the abundance of dinoflagellates discharged per tank and per ship, according to the annual ship traffic. This chapter will be submitted to the journal Marine Pollution Bulletin. -- Keywords: Dinoflagellates, non-indigenous species introductions, Ballast water, Ballast sediments, propagule pressure

Ship-trip data

Ship-trips between source and recipient regions, including corresponding ballast water volum

Data from: Propagule pressure in the presence of uncertainty: extending the utility of proxy variables with hierarchical models

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 confounding management 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 = 0·058) at small scales and only marginal accuracy at large scales (overall R2 = 0·169). 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, with maximum 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 to manage propagule pressure can be estimated within a statistical framework

Effect of temperature on chlorine treatment for elimination of freshwater phytoplankton in ballast water: bench scale test

Chlorine efficacy as a biocide for ballast water treatment was investigated under warm-cold temperatures, across winter and summer seasons. Freshwater phytoplankton samples were collected and acclimated under in situ environmental conditions ranging from 2-22 °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 0.2 ppm, phytoplankton densities were reduced more than 50 % without cell resurgence. Similar reduction was recorded immediately after exposure when chlorine concentrations were higher than 3 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.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

COMPARISON OF POTENTIAL ENVIRONMENTAL IMPACTS ON THE PRODUCTION AND USE OF HIGH AND LOW SULFUR REGULAR DIESEL BY LIFE CYCLE ASSESSMENT

This paper provides a comparative analysis using the concept of life cycle assessment (LCA), between high-sulfur (3 000 ppm) and low-sulfur diesel (500 ppm) diesel. The comparative LCA considers the stages of production, transport and oil refining, as well as the transport of refined products and their respective end use. This last stage of the life cycle is important for the analysis of potential environmental impacts, due to sulfur oxide (SO X) emissions, which contribute to the formation of acid rain, damage air quality and the ecosystem (land and water acidification), causing gradual damage to human health and the environment. Therefore, comparative LCA identifies critical points from the environmental perspective, weighing the contributions of pollu-tants (NO2, CH4and CO2) known as greenhouse gases (GHG) and criteria pollutants (CO, SO X, NO Xw, VOC's and PM). Simapro 7,2® was used to simulate and evaluate potential environmental impacts generated during the production and use by end consumers of the two fossil fuels. In order to evaluate the impact categories, two methods available in said calculation tool were selected: the first is the IPCC-2007 (GWP-100 years), which estimates the carbon footprint and the contributions of each stage of the production chain to the "Global War-ming" effect. The second method of evaluation is the Impact 2002+, which assesses the various contributions to the categories of toxicity to "Human Health", "Ecosystem Quality", "Climate Change" and "Depletion of Natural Resources". Thus, the preliminary results of comparative LCA show a slight increase in the carbon footprint (total emissions of CO2 equivalent in the productive chain) of low-sulfur diesel, approximately 3,8% compared to high-sulfur diesel, as a result of the increased emissions generated by the operation of the hydrogenation plant. However, low-sulfur diesel achieves a significant reduction of about 80% in comparison with high-sulfur diesel, in terms of damage to "Human Health" and "Ecosystem Quality". On the contrary, there was an increase of 2% and 6% in the categories of "Climate Change" and "Depletion of Natural Resources", respectively. Finally, despite the minor increase in the carbon footprint, although with remarkable reductions in "Ecosystem Quality" and "Human Health", the production and use of low-sulfur diesel has a single score of environmental impact equivalent to 0,23 milli points (mPt) compared to the single score obtained by high-sulfur diesel of 1,23 (mPt).En el presente trabajo se realiza un estudio comparativo utilizando el concepto de análisis de ciclo de vida (ACV), entre los combustibles diesel de alto azufre (3 000 ppm) y diesel de bajo azufre (500 ppm). El ACV comparativo contempla las etapas de producción, transporte y refinación de crudo, así como el transporte de refinados y su respectivo uso final. Esta última etapa del ciclo de vida, es importante para el análisis de potenciales impactos ambientales, dado que las emisiones de óxidos de azufre (SO X) contribuyen a la formación de lluvia ácida, deterioran la calidad del aire y el ecosistema (acidificación terrestre y acuática), causando paulatinamente daños en la salud humana y el medio ambiente. De este modo, el ACV comparativo permite identificar los puntos críticos desde la perspectiva ambiental, valorando los aportes de sustancias contaminantes (NO2, CH4 y CO2) clasificadas como gases de efecto invernadero (GEI) y algunos contaminantes criterio (CO, SO X, NO X, VOC's y MP). Mediante la herramienta Simapro 7.2® se simulan y evalúan los impactos ambientales potenciales generados durante la cadena productiva y el uso por los consumidores finales de los dos combustibles fósiles. Para la evaluación de las categorías de impacto se seleccionaron dos métodos disponibles en la herramienta de cálculo mencionada: el primero de ellos corresponde al IPCC-2007 (GWP-100años), con el cual se estimó la huella de carbono y las contribuciones de cada etapa de la cadena productiva al efecto "Calentamiento Global". El segundo método de evaluación concierne al Impact 2002+, el cual permite valorar los diferentes aportes a las categorías de toxicidad a la "Salud Humana", "Calidad del Ecosistema", "Cambio Climático y "Agotamiento de los Recursos Naturales". De esta manera, los resultados preliminares del ACV comparativo muestran un ligero incremento en la huella de carbono (emisiones totales de CO2equivalente en la cadena productiva) del diesel de bajo azufre, aproximadamente de 3,8% con relación al diesel de alto azufre, esto como consecuencia del incremento de emisiones generado por la operación de la planta de hidrotratamiento. Sin embargo, el diesel de bajo azufre alcanza una reducción significativa del orden de 80% con respecto al diesel de alto azufre, en términos de menor afectación a la "Salud Humana" y "Calidad del Ecosistema", mientras que por el contrario se observa un incremento del 2% y 6% en las categorías de "Cambio Climático" y "Agotamiento de los Recursos Naturales" respectivamente. Finalmente y a pesar del leve aumento en la huella de carbono, pero con notables reducciones en los aspectos de "Calidad del Ecosistema" y "Salud Humana", la producción y el uso del combustible diesel de bajo azufre alcanza una puntuación única de impacto ambiental equivalente a 0,23 mili puntos (mPt) comparada con la puntuación única obtenida por el diesel de alto azufre correspondiente a 1,23 (mPt).No presente trabalho é realizado um estudo comparativo utilizando o conceito de análise de ciclo de vida (ACV), entre os combustíveis diesel de alto teor de enxofre (3 000 ppm) e diesel de baixo teor de enxofre (500 ppm). O ACV comparativo contempla as etapas de produção, transporte e refinação de cru, assim como o transporte de refinados e seu respectivo uso final. Esta última etapa do ciclo de vida é importante para a análise de potenciais impactos ambientais, dado que as emissões de óxidos de enxofre (SO X) contribuem para a formação de chuva ácida, deterioram a qualidade do ar e do ecossistema (acidificação terrestre e aquática), causando paulatinamente danos para a saúde humana e para o meio ambiente. Deste modo, o ACV comparativo permite identificar os pontos críticos desde a perspectiva ambiental, avaliando as contribuições de substâncias contaminantes (NO2, CH4 e CO2) classificadas como gases de efeito estufa (GEI) e alguns contaminantes critério (CO, SO X , NO X , VOC's e MP). Mediante a ferramenta Simapro 7.2® são simulados e avaliados os impactos ambientais potenciais gerados durante a cadeia produtiva e o uso pelos consumidores finais dos dois combustíveis fósseis. Para a avaliação das categorias de impacto foram selecionados dois métodos disponíveis na ferramenta de cálculo mencionada: o primeiro deles corresponde ao IPCC-2007 (GWP-100 anos), com o qual foi estimada a pegada de carbono e as contribuições de cada etapa da cadeia produtiva para o efeito "Aquecimento Global". O segundo método de avaliação concerne ao Impact 2002+, o qual permite avaliar as diferentes contribuições para as categorias de toxicidade para a "Saúde Humana", "Qualidade do Ecossistema", "Mudança Climática" e "Esgotamento dos Recursos Naturais". Desta maneira, os resultados preliminares do ACV comparativo mostram um leve aumento na pegada de carbono (emissões totais de CO2 equivalente na cadeia produtiva) do diesel de baixo teor de enxofre, aproximadamente de 3,8% com relação ao diesel de alto enxofre, isto como consequência do aumento de emissões gerado pela operação da planta de hidrotratamento. Porém, o diesel de baixo teor de enxofre alcança uma redução significativa da ordem de 80% com relação ao diesel de alto teor de enxofre, em termos de menor afetação para a "Saúde Humana" e "Qualidade do Ecossistema", enquanto que ao contrário é observado um aumento de 2% e 6% nas categorias de "Mudança Climática" e "Esgotamento dos Recursos Naturais" respectivamente. Finalmente, e apesar do leve aumento na pegada de carbono, mas com notáveis reduções nos aspectos de "Qualidade do Ecossistema" e "Saúde Humana", a produção e o uso do combustível diesel de baixo teor de enxofre alcança uma pontuação única de impacto ambiental equivalente a 0,23 mili pontos (mPt) comparada com a pontuação única obtida pelo diesel de alto teor de enxofre correspondente a 1,23 (mPt)

Pacific Zooplankton

Samples of zooplankton from the ballast water of ships arriving to Pacific Canad

Atlantic Zooplankton

Samples of zooplankton from the ballast water of ships arriving to Atlantic Canad

Biological testing of ships’ ballast water indicates challenges for the implementation of the Ballast Water Management Convention

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) aim at 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 indicator microbes 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 water management system, filter mesh size associated with the system and 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