Diverse bacterial hosts and potential risk of antibiotic resistomes in ship ballast water revealed by metagenomic binning.

Ship ballast water promoting the long-range migration of antibiotic resistance genes (ARGs) has raised a great concern. This study attempted to reveal ARGs profile in ballast water and decipher their hosts and potential risk using metagenomic approaches. In total, 710 subtypes across 26 ARG types were identified among the ballast water samples from 13 ships of 11 countries and regions, and multidrug resistance genes were the most dominant ARGs. The composition of ARGs were obviously different across samples, and only 5% of the ARG subtypes were shared by all samples. Procrustes analysis showed the bacterial community contributed more than the mobile genetic elements (MGEs) in shaping the antibiotic resistome. Further, 79 metagenome-assembled genomes (46 genera belong to four phyla) were identified as ARG hosts, with predominantly affiliated with the Proteobacteria. Notably, potential human pathogens (Alcaligenes, Mycolicibacterium, Rhodococcus and Pseudomonas) were also recognized as the ARG hosts. Above 30% of the ARGs hosts contained the MGEs simultaneously, supporting a pronounced horizontal gene transfer capability. A total of 43 subtypes (six percent of overall ARGs) of ARGs were assessed with high-risk, of which 23 subtypes belonged to risk Rank I (including rsmA, ugd, etc.) and 20 subtypes to the risk Rank II (including aac(6)-I, sul1, etc.). In addition, antibiotic resistance risk index indicated the risk of ARGs in ballast water from choke points of maritime trade routes was significantly higher than that from other regions. Overall, this study offers insights for risk evaluation and management of antibiotic resistance in ballast water.

Electrokinetic motion and viability assessment of algae with a polyethylene glycol-dextran interface.

At present, there is still limited report on the electrokinetic (EK) behavior of bioparticles at the interface of an aqueous two-phase system. In this paper, the EK motion and viability assessment of live algae mixed with the NaClO treated dead algae were carried out at the interface formed by polyethylene glycol (PEG)-rich phase and dextran (DEX)-rich phase in a straight microchannel. The experimental results show that both the live and dead algae at the PEG-DEX interface migrate from the negative electrode to the positive electrode, and the EK velocity of live algae at the interface is slightly larger than that of the dead ones with similar diameters. For either live or dead algae, the EK velocity at the interface decreases with the increase in diameter. A size-velocity curve was used to evaluate the viability of the algae. As most of the microorganisms in ballast water are algae, the method in this paper provides a promising way to detect and evaluate the live microorganism in treated ballast water of a ship.

Global Impacts of a Bilateral Trade Policy on Ballast Water-Mediated Species Spread Risk: A Case Study of Sino-US Trade.

A trade policy could generate both economic and environmental impacts. This work is focused on the impacts of a bilateral trade policy on ballast water-mediated nonindigenous species (NIS) spread risk. Taking the hypothetical Sino-US trade restriction as an example, we integrate a computable general equilibrium model and a higher-order NIS spread risk assessment model to examine the impacts of bilateral trade policy on both the economy and NIS spread risks. We have two important findings. First, the Sino-US trade restriction would cause decreases in NIS spread risks to China and the US, as well as to three quarters of worldwide countries/regions. However, the rest one fourth would experience increased NIS spread risks. Second, the relationship between changes in exports and changes in NIS spread risks might not be directly proportional. This is observed with 46% of countries and regions that would see their exports increase but their NIS spread risks drop, with positive impacts on both their economies and environment under the Sino-US trade restriction. These results reveal both broader global impacts as well as the decoupled economic and ecological impacts of a bilateral trade policy. These broader impacts demonstrate the necessity for national governments, which are parties to bilateral agreements to give due consideration to the economic and environmental impacts on countries and regions outside of the agreement.

The prevalence of potential pathogens in ballast water and sediments of oceangoing vessels and implications for management.

Ballast water and sediments can serve as prominent vectors for the widespread dispersal of pathogens between geographically distant areas. However, information regarding the diversity and distribution of the bacterial pathogens in ballast water and sediments is highly limited. In this study, using high-throughput sequencing and quantitative PCR, we investigated the composition and abundance of potential pathogens, and their associations with indicator microorganisms. We accordingly detected 48 potential bacterial pathogens in the assessed ballast water and sediments, among which there were significant differences in the compositions and abundances of pathogenic bacterial communities characterizing ballast water and sediments. Rhodococcus erythropolis, Bacteroides vulgatus, and Vibrio campbellii were identified as predominant pathogens in ballast water, whereas Pseudomonas stutzeri, Mycobacterium paragordonae, and Bacillus anthracis predominated in ballast sediments. Bacteroidetes, Vibrio alginolyticus, Vibrio parahaemolyticus, and Escherichia coli were generally detected with median values of 8.54 × 103-1.22 × 107 gene copies (GC)/100 mL and 1.16 × 107-3.97 × 109 GC/100 g in ballast water and sediments, respectively. Notably, the concentrations of Shigella sp., Staphylococcus aureus, and V. alginolyticus were significantly higher in ballast sediments than in the water. In addition, our findings tend to confirm that the indicator species specified by the International Maritime Organization (IMO) might underestimate the pathogen risk in the ballast water and sediments, as these bacteria were unable to predict some potential pathogens assessed in this study. In summary, this study provides a comprehensive insight into the spectrum of the potential pathogens that transferred by ship ballast tanks and emphasizes the need for the implementation of IMO convention on ballast sediment management.

First record in Europe of the Asian gobiid, shimofuri (marbled) goby Tridentiger bifasciatus Steindachner, 1881.

In November 2022, two shimofuri (marbled) gobies Tridentiger bifasciatus Steindachner, 1881 were caught in the Gent-Terneuzen shipping canal, Belgium. It is the first record of the species in Europe. Outside its native distribution area in Japan, China and South Korea, thus far the shimofuri goby has been observed only on the West Coast of the USA, where established populations exist. The introduction vector potentially was ballast water exchange.

Toxicity evaluation of chlorinated natural water using Photobacterium phosphoreum: Implications for ballast water management.

Chlorination of ballast water could produce harmful disinfection by-products (DBPs) and total residual oxidants. The International Maritime Organization calls for toxicity testing of discharged ballast water with fish, crustacea and algae to reduce the risk, but it is difficult to evaluate the toxicity of treated ballast water in a short time. Therefore, the purpose of this study was to analyze the applicability of luminescent bacteria to the assessment of residual toxicity of chlorinated ballast water. The toxicity unit for all treated samples were higher for Photobacterium phosphoreum than for microalgae (Selenastrum capricornutum and Chlorella pyrenoidosa), after adding neutralizer, all samples showed little effect on the luminescent bacteria and microalgae. For the DBPs, except for 2,4,6-Tribromophenol, Photobacterium phosphoreum could produce more sensitive and rapid test results than other species, the results in Photobacterium phosphoreum showed that the toxicity of DBPs in order of: 2,4-Dibromophenol > 2,6-Dibromophenol > 2,4,6-Tribromophenol > Monobromoacetic acid > Dibromoacetic acid > Tribromoacetic acid, and most binary mixtures (aromatic DBPs and aliphatic DBPs) presented synergistic effects based on the CA model. The aromatic DBPs in ballast water deserve more attention. In general, for ballast water management, the use of luminescent bacteria to evaluate the toxicity of treated ballast water and DBPs is desirable, this study could provide beneficial information for enhancing ballast water management.

The first record of burrowing goby Trypauchen vagina (Bloch & Schneider, 1801) (Gobiiformes: Gobiidae: Amblyopinae) from the Atlantic Ocean.

The burrowing goby Trypauchen vagina has been reported from Brazil for the first time. This goby occurs naturally in the Indo-Pacific region, where it is typically found burrowed in the bottom substrata of marine or brackish waters. Given its rapid development, extended longevity and multiple spawning cycles, the species is represented by large populations in Asian countries. The authors discuss the occurrence of this species in Brazilian waters and conclude that it was introduced via the ballast water of vessels arriving from Asia. They also compare this exotic taxon with the native Brazilian gobies, including Akko dionaea, Microdesmus and Gobioides, that have burrowing habits.

Citizen science as a tool for understanding the silent dispersion of toadfish Opsanus beta (Goode and Bean, 1880).

Citizen science is an excellent tool in studies of the spatial distribution of non-native species. In Brazil, Opsanus beta has recently been introduced. Studies indicate the occurrence of this species in five estuaries off the Brazilian coast (Guanabara Bay, Sepetiba Bay, Santos Bay, Paranaguá Estuarine Complex and Guaratuba Bay). The present study aims to understand the dispersion of this species on the Brazilian coast through citizen science. Between January and May 2021, information about O. beta was weekly posted in 32 recreational fishing Facebook groups. Sixty-five fishers reported catches of O. beta in estuaries (Guanabara Bay, Sepetiba Bay, Santos Bay and Paranaguá Estuarine Complex). In addition, there were reports from other shallow areas outside adjacent estuaries (Bertioga and Peruíbe, in Sao Paulo State) and the first occurrence record for Laguna (Santa Catarina State), a southern estuarine zone (28° 29' 45″ S to 48° 45' 36″ W). In four estuaries along the Brazilian coast where O. beta was recorded, there are internal ports that trade with countries from the Gulf of Mexico and Caribbean Sea (species original range), indicating ballast water as a possible introduction route. In Laguna, the introduction may have occurred by maritime cabotage services. The reproductive capacity, the aquarists' interest, the absence of introduction policies aimed at this species and the cabotage fleet transportation may be factors that help further extend the dispersal of O. beta on the Brazilian coast.

Bacterial communities in ballast tanks of cargo vessels - Shaped by salinity, treatment and the point of origin of the water but "hatch" its typical microbiome.

Ballast water is a main vector of introduction of potentially harmful or pathogenic aquatic organisms. The development of genetic tools for ballast water monitoring has been underway and highlighted as a source for accurate and reliable data for decision making. We used 16S rRNA gene amplicon sequencing to analyze the microbial communities found in the ballast water of fifteen commercial ships routed through two Estonian ports. In parallel, samples from the port area were collected at the same time each ship visited. Fluorescence microscopy was utilized to assess the effectiveness of the treatment applied to ballast water. In addition, supplemental samples were collected from Hamburg Port (Germany) and a ballast tank decontamination system used at this port. The composition and diversity of bacterial communities varied greatly between obtained samples. The application of UV treatment did not demonstrate significant reduction in species richness estimates. The composition of microbial communities was significantly influenced by salinity, treatment (mainly untreated or UV treated) and the point of origin of the ballast water. Over a hundred potentially pathogenic bacterial taxa were found in relatively high abundance, including in ballast water that had received UV treatment. These shortcomings of stand-alone UV treatment of ballast water, especially when weak treatment is applied insufficiently, highlight the danger of possible harmful effects arising over time and the need for genetic tools for ballast water monitoring and management.

Assessing the performance of four indicative analysis devices for ballast water compliance monitoring, considering organisms in the size range ≥10 to <50 µm.

To minimize the global transfer of harmful aquatic organisms and pathogens, the International Maritime Organization (IMO) has introduced the standard in Regulation D-2 to limit the number of viable organisms in ballast water discharged by ships. To meet the standard, many ships are installing ballast water management systems. Concurrently, regulators are looking for indicative analysis devices able to assess compliance with Regulation D-2, producing rapid, accurate and reliable results while being easy to operate. The purpose of this research is to compare four indicative analysis devices against detailed microscopy for measuring the size class of organisms ≥10 to <50 µm in minimum dimension (e.g., phytoplankton, including autotrophs, heterotrophs or mixotrophs), using field and laboratory tests. Comparisons were conducted on (treated) ballast water discharge samples collected across Canada during three consecutive years (2017-2019). During seven tests in 2019, paired ballast water uptake samples were also obtained, facilitating measurements before and after treatment was applied. Indicative analysis devices also were challenged with natural environmental samples containing different organism abundance levels, ranging from low (nominally <10 cells mL-1) to high (nominally >150 cells mL-1) during laboratory tests. While the indicative analysis devices examined during this research produced numeric estimates having weak correlations with the standard reference method, categorical outcomes (above/below the D-2 standard) had high agreement (89% or better) when assessing ballast water samples, but lower agreement (67% or poorer) during laboratory tests. There was a relatively high rate of false negative results measured by all devices during laboratory tests. Results provided by indicative analysis devices had higher uncertainty when organism abundances in ballast samples are below and close to the D-2 standards.

Economic and environmental impacts of ballast water management on Small Island Developing States and Least Developed Countries.

The Ballast Water Management Convention can decrease the introduction risk of harmful aquatic organisms and pathogens, yet the Convention increases shipping costs and causes subsequent economic impacts. This paper examines whether the Convention generates disproportionate invasion risk reduction results and economic impacts on Small Island Developing States (SIDS) and Least Developed Countries (LDCs). Risk reduction is estimated with an invasion risk assessment model based on a higher-order network, and the effects of the regulation on national economies and trade are estimated with an integrated shipping cost and computable general equilibrium modeling framework. Then we use the Lorenz curve to examine if the regulation generates risk or economic inequality among regions. Risk reduction ratios of all regions (except Singapore) are above 99%, which proves the effectiveness of the Convention. The Gini coefficient of 0.66 shows the inequality in risk changes relative to income levels among regions, but risk reductions across all nations vary without particularly high risks for SIDS and LDCs than for large economies. Similarly, we reveal inequality in economic impacts relative to income levels (the Gini coefficient is 0.58), but there is no evidence that SIDS and LDCs are disproportionately impacted compared to more developed regions. Most changes in GDP, real exports, and real imports of studied regions are minor (smaller than 0.1%). However, there are more noteworthy changes for select sectors and trade partners including Togo, Bangladesh, and Dominican Republic, whose exports may decrease for textiles and metal and chemicals. We conclude the Convention decreases biological invasion risk and does not generate disproportionate negative impacts on SIDS and LDCs.

Integrated Biological Risk and Cost Model Analysis Supports a Geopolitical Shift in Ballast Water Management.

This work evaluates efficacies of plausible ballast water management strategies and standards by integrating a global species spread risk assessment with a policy cost-effectiveness analysis. Specifically, we consider species spread risks and costs of port- and vessel-based strategies under both current organism concentration standards and stricter standards proposed by California. For each scenario, we estimate species spread risks and patterns using a higher-order analysis of a global ship-borne species spread model and estimate fleet costs for vessel- and barge-based ballast water treatment systems for each standard. We find that stricter standards may reduce species spread risk by a factor of 17 globally and would greatly simplify the complex network of ship-borne species spread. The current policy of IMO standards is most cost-effectively achieved through ship-based treatment, and that any additional risk reduction will be most cost-effectively achieved by port-based (or barge-based) technologies, particularly if these are strategically implemented at the top ports within the largest clusters. Barge-based ballast water management would require a shift in governance, and we suggest that this next level of policymaking could be feasible for special areas designated by the IMO, by State or multistate authorities, or by voluntary port applications.

Potentiometric Sensor Based on Carbon Paste Electrode for Monitoring Total Residual Chlorine in Electrolytically-Treated Ballast Water.

A new potentiometric sensor based on modified carbon paste electrode (CPE) was prepared for the sensitive and selective detection of total residual chlorine (TRC) in simulated electrolytically-treated ballast water (BW). The modified CPE was prepared using ferrocene (Fc) as the sensing species and paraffin oil as the binder. It is revealed that the addition of Fc can significantly shorten the response time and improve the reproducibility, selectivity, and stability of the sensor. The open circuit potential of the Fc-CPE is in linear proportion to the logarithm of TRC within the TRC concentration range from 1 mg∙dm-3 to 15 mg∙dm-3. In addition, the Fc-CPE sensor exhibits good selectivity to TRC over a wide concentration range of the possible co-exiting interference ions in seawater. The Fc-CPE electrode can be used as a convenient and reliable sensor for the continuous monitoring of TRC during the electrolytic treatment of BW.

Exceptions and exemptions under the ballast water management convention - Sustainable alternatives for ballast water management?

The International Convention for the Control and Management of Ships' Ballast Water and Sediments (BWM Convention) aims to mitigate the introduction risk of harmful aquatic organisms and pathogens (HAOP) via ships' ballast water and sediments. The BWM Convention has set regulations for ships to utilise exceptions and exemptions from ballast water management under specific circumstances. This study evaluated local and regional case studies to provide clarity for situations, where ships could be excepted or exempted from ballast water management without risking recipient locations to new introductions of HAOP. Ships may be excepted from ballast water management if all ballasting operations are conducted in the same location (Regulation A-3.5 of the BWM Convention). The same location case study determined whether the entire Vuosaari harbour (Helsinki, Finland) should be considered as the same location based on salinity and composition of HAOP between the two harbour terminals. The Vuosaari harbour case study revealed mismatching occurrences of HAOP between the harbour terminals, supporting the recommendation that exceptions based on the same location concept should be limited to the smallest feasible areas within a harbour. The other case studies evaluated whether ballast water exemptions could be granted for ships using two existing risk assessment (RA) methods (Joint Harmonised Procedure [JHP] and Same Risk Area [SRA]), consistent with Regulation A-4 of the BWM Convention. The JHP method compares salinity and presence of target species (TS) between donor and recipient ports to indicate the introduction risk (high or low) attributed to transferring unmanaged ballast water. The SRA method uses a biophysical model to determine whether HAOP could naturally disperse between ports, regardless of their transportation in ballast water. The results of the JHP case study for the Baltic Sea and North-East Atlantic Ocean determined that over 97% of shipping routes within these regions resulted in a high-risk indication. The one route assessed in the Gulf of Maine, North America also resulted in a high-risk outcome. The SRA assessment resulted in an overall weak connectivity between all ports assessed within the Gulf of the St. Lawrence, indicating that a SRA-based exemption would not be appropriate for the entire study area. In summary, exceptions and exemptions should not be considered as common alternatives for ballast water management. The availability of recent and detailed species occurrence data was considered the most important factor to conduct a successful and reliable RA. SRA models should include biological factors that influence larval dispersal and recruitment potential (e.g., pelagic larval duration, settlement period) to provide a more realistic estimation of natural dispersal.

First genetic record of the non-native muzzled blenny Omobranchus punctatus (Teleostei: Blenniidae) in the Atlantic Coast of Central and South America.

In this study we sequenced two mitochondrial (COI and 16S rRNA) and one nuclear (18S rRNA) gene fragment of an introduced muzzled blenny (Omobranchus punctatus) specimen collected from the Orinoco Delta (Gulf of Paria estuary) in Venezuela. This is the first genetic data generated for this species' introduced range in Central and South America, suggesting an introduction from the Indian Ocean.

Potential impacts of ballast water regulations on international trade, shipping patterns, and the global economy: An integrated transportation and economic modeling assessment.

Global ballast water management regulations aiming to decrease aquatic species invasion require actions that can increase shipping costs. We employ an integrated shipping cost and global economic modeling approach to investigate the impacts of ballast water regulations on bilateral trade, national economies, and shipping patterns. Given the potential need for more stringent regulation at regional hotspots of species invasions, this work considers two ballast water treatment policy scenarios: implementation of current international regulations, and a possible stricter regional regulation that targets ships traveling to and from the United States while other vessels continue to face current standards. We find that ballast water management compliance costs under both scenarios lead to modest negative impacts on international trade and national economies overall. However, stricter regulations applied to U.S. ports are expected to have large negative impacts on bilateral trade of several specific commodities for a few countries. Trade diversion causes decreased U.S. imports of some products, leading to minor economic welfare losses.

Changes in the ballast water tank bacterial community during a trans-sea voyage: Elucidation through next generation DNA sequencing.

Ballast water (BW) mediated bioinvasion is one of the greatest threats to the health of aquatic ecosystems. Bacteria, unlike higher organisms, are transferred in large numbers through BW. Owing to their abundance and potential pathogenicity, they pose a direct threat to the prevailing microbiome in the recipient waters and also to human health. This study investigated the changes in the BW tank bacterial community during a trans-sea voyage from Visakhapatnam port, located along the east coast of India (Bay of Bengal) to Mumbai port, located along the west coast of India (Arabian Sea). Next generation sequencing was used to explore the unculturable segment of bacteria. The BW tank conditions led to a decrease in photoautotrophs and non-spore forming bacteria. On the other hand, biofilm forming and antibiotic producing bacteria, nutrient limiting condition sustaining bacteria, and those capable of synthesizing enzymes prerequisite for active metabolism under stress, increased over time. The shifts in the bacterial community were dependent on mechanisms adopted by the clades to cope with the BW tank conditions. Functional prediction of the bacterial community revealed a significant increase in the core metabolic functions, which enabled the survival of such bacteria. As the voyage progressed, an increase in the total viable bacteria in BW tanks could be attributed to the decrease in the abundance of phytoplankton and zooplankton. At the end of the voyage, the bacterial community in the BW tanks was significantly different, and the species diversity and richness were higher than that of the natural seawater (source water). Pathogenic species were more abundant during mid-voyage than at the end of the voyage, suggesting that voyage duration influences the pathogenic bacterial community. Investigating the fate of the discharged bacterial population at the deballasting point is a way forward in the assessment of marine bioinvasion.

Assessment of the efficiency of controls to prevent biologic invasions at the San Lorenzo Port, Argentina.

The problem created by invasive non-native species through ships' ballast water has caused the International Maritime Organization (IMO), through the Ballast Water Management (BWM) Convention and many countries to develop their own laws to prevent their introduction. One of the most important non-native species in Argentina, the golden mussel (Limnoperna fortunei), causes a significant economic impact on the Plata Basin. Argentina has a great amount of maritime and fluvial ports that receive ships from different regions of the world. Particularly, the San Lorenzo-San Martín Port Complex (here termed SLOR), placed in the terminal portion of the Paraná Basin, receives ocean ships with great loading capacity, which increases the possibility of invasions and the need of an adequate environmental management. This work proposes to estimate the potential vulnerability of SLOR port, in relation with the origin of the ballast water and its volume. For this purpose, an adaptation of the risk assessment model of the GloBallast Program was used. The results suggest that SLOR has important similarities with different fluvial ports of the world, especially in Brazil and China. However the amount of ships coming from the nearest estuary waters, where the diversity of invasive species has major effects, is also important. This article provides the necessary information to conduct the efforts through surveys and enforcement regulations, and could be the foundation for future research using global data that could provide basic information for other fluvial ports with similar features.

Non-native species spread in a complex network: the interaction of global transport and local population dynamics determines invasion success.

The number of released individuals, which is a component of propagule pressure, is considered to be a major driver for the establishment success of non-native species. However, propagule pressure is often assumed to result from single or few release events, which does not necessarily apply to the frequent releases of invertebrates or other taxa through global transport. For instance, the high intensity of global shipping may result in frequent releases of large numbers of individuals, and the complexity of shipping dynamics impedes predictions of invasion dynamics. Here, we present a mathematical model for the spread of planktonic organisms by global shipping, using the history of movements by 33 566 ships among 1477 ports to simulate population dynamics for the comb jelly Mnemiopsis leidyi as a case study. The degree of propagule pressure at one site resulted from the coincident arrival of individuals from other sites with native or non-native populations. Key to sequential spread in European waters was a readily available source of propagules and a suitable recipient environment. These propagules were derived from previously introduced 'bridgehead' populations supplemented with those from native sources. Invasion success is therefore determined by the complex interaction of global shipping and local population dynamics. The general findings probably hold true for the spread of species in other complex systems, such as insects or plant seeds exchanged via commercial trade or transport.

Dielectrophoretic separation of microalgae cells in ballast water in a microfluidic chip.

The composition of the ship's ballast water is complex and contains a large number of microalgae cells, bacteria, microplastics, and other microparticles. To increase the accuracy and efficiency of detection of the microalgae cells in ballast water, a new microfluidic chip for continuous separation of microalgae cells based on alternating current dielectrophoresis was proposed. In this microfluidic chip, one piece of 3-dimensional electrode is embedded on one side and eight discrete electrodes are arranged on the other side of the microchannel. An insulated triangular structure between electrodes is designed for increasing the inhomogeneity of the electric field distribution and enhancing the dielectrophoresis (DEP) force. A sheath flow is designed to focus the microparticles near the electrode, so as to increase the suffered DEP force and improve separation efficiency. To demonstrate the performance of the microfluidic separation chip, we developed two species of microalgae cells (Platymonas and Closterium) and a kind of microplastics to be used as test samples. Analyses of the related parameters and separation experiments by our designed microfluidic chip were then conducted. The results show that the presented method can separate the microalgae cells from the mixture efficiently, and this is the first time to separate two or more species of microalgae cells in a microfluidic chip by using negative and positive DEP force simultaneously, and moreover it has some advantages including simple operation, high efficiency, low cost, and small size and has great potential in on-site pretreatment of ballast water.