Verification of mid-ocean ballast water exchange using naturally occurring coastal tracers

We examined methods for verifying whether or not ships have performed mid-ocean ballast water exchange (BWE) on four commercial vessels operating in the Pacific and Atlantic Oceans. During BWE, a ship replaces the coastal water in its ballast tanks with water drawn from the open ocean, which is considered to harbor fewer organisms capable of establishing in coastal environments. We measured concentrations of several naturally occurring chemical tracers (salinity, six trace elements, colored dissolved organic matter fluorescence and radium isotopes) along ocean transects and in ballast tanks subjected to varying degrees of BWE (0-99%). Many coastal tracers showed significant concentration changes due to BWE, and our ability to detect differences between exchanged and unexchanged ballast tanks was greatest under multivariate analysis. An expanded dataset, which includes additional geographic regions, is now needed to test the generality of our results.     

Changes in zooplankton abundance and diversity after ballast water exchange in regional seas

A study of the efficiency of ballast water exchange (BWE) in regional seas was carried out to assess this management method in reducing the risk of introducing non-native species. Zooplankton samples were taken before and after exchange on ten voyages where BWE took place (North Sea, English Channel, Irish Sea and Bay of Biscay). Zooplankton abundance was always reduced after exchange, but diversity increased on eight occasions. The greatest changes occurred when the source port water was of low salinity and when exchange took place in deeper waters further from land. However, it was clear that BWE did not remove all the source port taxa and this method is unlikely to provide a consistent and effective method of managing ballast water in regional seas.     

Denaturing gradient gel electrophoresis shows that bacterial communities change with mid-ocean ballast water exchange

Ships carry ballast water for better stability and to control trim. However, the discharge of ballast water near ports is known to transport invasive species from one coastal area to another. The exchange of ballast water on the high seas is supposed to reduce such invasions of exotic species. In this study, we used denaturing gradient gel electrophoresis (DGGE) to analyze the composition of the bacterial community in ballast water before and after such a mid-ocean exchange, and we also measured total bacterial counts. Our findings confirmed that the ballast water was replaced by the mid-ocean exchange, as indicated by the marked change in the composition of the bacterial community. There was also a significant decrease in bacterial abundance after the mid-ocean exchange. Finally, our findings support the incubation hypothesis, because the composition of the bacterial communities changed over time within the same ballast water.     

Results from the first ballast water sampling study in the Mediterranean Sea - the Port of Koper study

The ongoing transfer of harmful organisms by shipping, especially via ballast water transport, may result in a change of biodiversity, alteration of ecosystems, negative impacts on human health and economic loss. Species introductions which cause irreversible consequences to receiving environments and economies call for particular attention. One critical issue is a need to evaluate the quantities and processes of species introductions. Consequently ballast water was sampled on 15 ships calling at the Port of Koper, Slovenia. This was the first ballast water sampling study in the Mediterranean Sea. This paper summarises the sampling results. Samples were analysed for all types of aquatic organisms including bacteria. The results may be considered as background information for an initial risk assessment of future species introductions - an important tool for the implementation of ballast water management measures.     

Management and environmental risk study of the physicochemical parameters of ballast water

Shipping is a vital industry for the global economy. Stability of ships, provided by ballast water, is a crucial factor for cargo loading and unloading processes. Ballast water treatment has practical significance in terms of environmental issues, ecosystem, and human health, because ships discharge this water into the environment before loading their cargos. This study reviews the common methods for ballast water management – exchange, heating, filtration, ultrasonic treatment, ultraviolet irradiation, chemicals, and gas supersaturation – to select the best one. This study compares water temperature, salinity, dissolved oxygen, polycyclic aromatic hydrocarbons (PAHs), and heavy metals (Co, Cr, Ni, Pb) for ballast tanks of selected ships with the recipient port environment in the Persian Gulf as a case study. The exchange of ballast water in the ocean and/or its treatment on board to prevent inadvertent effects on the environment's physicochemical conditions is related to vessel characteristics, legislation, and the environmental condition. Ecological risk study showed that the salt content in ballast water is close to that of seawater, but the values of Cr (2.1 mg/l) and Ni (0.029 mg/l) in ballast water are higher than those in seawater (1 and 0.004 mg/l, respectively).     

Biological controls on bacterial populations in ballast water during ocean transit

Bacteria (and viruses) numerically dominate ballast water communities, but what controls their population dynamics during transit is largely unexplored. Here, bacterial abundance, net and intrinsic growth rates, and grazing mortality were determined during a trans-Atlantic voyage. The effects of grazing pressure by microzooplankton on heterotrophic bacteria during transit were determined for source port, mid-ocean exchange (MOE), and six-day-old source port ballast water. When the grazer component was removed, bacterial abundances significantly increased. Additionally, we determined that the grazer-mediated mortality for ballast water originating from ports was greater than MOE water and that mortality decreased over time for the source port ballast water. This study shows that bacterial populations in transit are controlled by microzooplankton grazing. If these findings are representative of ballast water environments, they suggest that if the grazing component is selectively removed by various treatment methods, bacterial populations may increase; this could have environmental and human health consequences.     

Variability in invasion risk for ballast water exchange on the Scotian Shelf of eastern Canada

A semi-quantitative risk assessment model for dispersion of ballast water organisms in shelf seas is applied to the Scotian Shelf region of eastern Canada. The ballast water exchange process is simulated as the dispersion of tracer released into the surface layer of an ocean circulation model of the region. Circulation model variability is driven by wind stress from a cyclical year of forcing representing climatological storminess. Dispersion metrics related to invasion risk are developed and incorporated into a risk equation that computes the relative overall risk of invasion for ballast water exchange segments along vessel tracks crossing the shelf. Three hundred and sixty dispersion simulations are done for each segment of each of six tracks. Because the flow fields represent climatological variability in shelf circulation, the application of the risk assessment model captures the expected variability in invasion risk. Model results indicate that more than an order of magnitude variation in risk can exist along a given vessel track, and that tracks with offshelf segments provide a lower risk option compared to onshelf tracks. The model provides quantitative guidance to regulators regarding what is an acceptable trip diversion and can aid in numerous other management decisions.     

Analysis of recent vessel arrivals and ballast water discharge in Alaska: toward assessing ship-mediated invasion risk

Ships are a dominant vector for biological invasions through ballast water discharge (BWD) and hull fouling. Here, we provide a first comprehensive analysis of shipping in Alaska, summarizing (a) the number, type and origin of vessel arrivals to Alaska for 2003 and 2004, (b) the spatial and temporal variation in vessel traffic, and (c) the available data on ballast water discharge in order to prioritize locations for tracking biological invasions. Most arrivals were passenger vessels, followed by ferries and fishing vessels, all of which carried little ballast water. Regional and seasonal patterns in arrivals and BWD were unevenly distributed among vessel types. The majority of vessels reporting BWD were from foreign ports, and most of this ballast was untreated. The largest volumes of ballast were from tankers at Valdez and Kenai Peninsula ports. Although Alaska has few documented invasions, opportunities for ship-mediated transfer now appear high and warrant further scrutiny.     

Shipboard trials of an ozone-based ballast water treatment system

Legislation introduced by the United Nations International Maritime Organization (IMO) has focused primarily on standards defining successful treatments designed to remove invasive species entrained in ballast water. An earlier shipboard study found that ozone introduced into salt water ballast resulted in the formation of bromine compounds, measured as total residual oxidants (TRO) that were toxic to both bacteria and plankton. However, the diffuser system employed to deliver ozone to the ballast water tanks resulted in patchiness in TRO distribution and toxicity to entrained organisms. In this follow-up study, the shipboard diffuser system was replaced by a single Venturi-type injection system designed to deliver a more homogeneous biocide distribution. Within-tank variability in TRO levels and associated toxicity to zooplankton, phytoplankton and marine bacteria was measured via a matrix of tubes deployed to sample different locations in treated and untreated (control) tanks. Three trials were conducted aboard the oil tanker S/T Prince William Sound in the Strait of Juan de Fuca off Port Angeles, Washington State, USA, between June and December 2007. Mortalities of plankton and bacteria and oxidant concentrations were recorded for treated and untreated ballast water up to 3 days following treatment, and residual toxicity beyond this period was measured by bioassay of standard test organisms. Results indicated uniform compliance with current IMO standards, but only partial compliance with other existing and pending ballast water legislation.     

Intra-coastal ballast water flux and the potential for secondary spread of non-native species on the US West Coast

Ballast water is a dominant mechanism for the interoceanic and transoceanic dispersal of aquatic non-native species (ANS), but few studies have addressed ANS transfers via smaller scale vessel movements. We analyzed ballast water reporting records and ANS occurrence data from four US West Coast port systems to examine patterns of intra-coastal ballast water transfer, and assess how ballast transfers may have influenced the secondary spread of ANS. In 2005, one third of the vessels arriving to the US West Coast originated at one of four West Coast port systems (intra-coastal traffic). These vessels transported and discharged 27% (5,987,588 MT) of the total ballast water volume discharged at these ports that year. The overlap of ANS (shared species) among port systems varied between 3% and 80%, with the largest overlap occurring between San Francisco Bay and LA/Long Beach. Our results suggest that intra-coastal ballast water needs further consideration as an invasion pathway, especially as efforts to promote short-sea shipping are being developed.     

Effect of mid-oceanic ballast water exchange on virus-like particle abundance during two trans-Pacific voyages

Ballast water is a potential source of invasive species, including viruses that target a variety of hosts. We sampled ballast during two trans-Pacific voyages and analyzed the efficacy of mid-oceanic exchange in reducing virus-like particle (VLP) abundance. Exchange did not significantly reduce virus abundance during the first voyage (P = 0.874), whereas it reduced viral abundance 3.9-fold from 1.8 × 10⁷ to 0.47 × 10⁷ VLP mL⁻¹ during the second voyage (P < 0.0001). Despite the impact of exchange during the second voyage, virus abundances were not significantly different between exchanged and unexchanged tanks upon arrival in Canada (P = 0.363) and Canadian port water samples (P = 0.502). Regressions between environmental parameters and VLP abundance uncovered negative correlations between salinity and viral abundance during one, and dissolved oxygen and viral abundance during the second voyage. In summary, ballast tanks are highly variable with respect to total virus abundance, and the efficacy of exchange requires investigation into the dynamics of specific viruses.     

Vessel traffic patterns in the Port of Kaohsiung and the management implications for preventing the introduction of non-indigenous aquatic species

Data on shipping traffic in one of the busiest seaports in the world, the Port of Kaohsiung, were analyzed to evaluate the implications for ballast water management. Results show that 67% of the arriving vessels were registered to a flag of convenience, which typically have a lower degree of environmental records. The top five donor countries historically suffer from harmful algal bloom problems. The short journey and busy trading between these countries and Taiwan lead to a higher risk of inoculation. In addition, only 1.4% of all vessels visited more than once every year during the 9-year span, indicating that the port authority encounters many new vessels each year. These findings could influence the design and application of ballast water management strategies as well as highlight the challenges in their implementation. We suggest that an analysis of vessel traffic patterns should be coupled with other useful vessel information to make risk assessment successful.     

Potential risk of harmful algae transport by ballast waters: the case of Bilbao Harbour

Ballast water exchange was measured for the first time in Bilbao Harbour, one of the most active of northern Spain. Between 1997 and 2006, 41,900,980.34 ballast water tn were loaded and 13,272,709 tn were discharged. Bilbao Harbour appears to be mainly a source of ballast water, 90% of which would be discharged in European harbours. We estimated that vessels carrying liquid and solid bulk have higher probabilities of exporting ballast water, whereas those with liquid bulk and containers are more likely to introduce it. From 30 potentially harmful phytoplankton species identified to date near harbour facilities, there would be a high risk of exporting at least Alexandrium minutum, Dinophysis sp., Heterosigma akashiwo, Karlodinium sp., Ostreopsis cf. siamensis, Pfiesteria-like and Prorocentrum minimum. Invasion risk by ballast water was tested by analyzing the response of six strains of H. akashiwo from different geographic areas to varying salinity. Results show that successful growth of foreign strains would be possible.     

Phytoplankton viability in ballast water from international commercial ships berthed at ports in Korea

We investigated the viability of phytoplankton from ballast water of international commercial ships berthed at the ports of Ulsan and Onsan, Korea. The incubation conditions used were temperatures of 13 °C to represent ambient water and 20 °C to represent the thermal optimum, as well as nutrients in ballast water, shipside water, and F/2 medium. Phytoplankton in new (∼7 days) and old (20 and 23 days) ballast water survived when incubated under the nutrients typical of shipside water and F/2 medium at 13 °C and 20 °C. Colonization process was mostly dominated by Skeletonema costatum, Cylindrotheca closterium and pennate diatoms (<10 μm in diameter). S. costatum and C. closterium were persistent during incubation time, whereas pennate diatoms dominated in the three types of media from doubling to last phase of growth. This study showed that bloom-forming and pennate diatoms appear to be the species most likely to become successfully established in the two ports.     

Macroalgal survival in ballast water tanks

Despite a large amount of research into invasive species and their introductions, there have been no studies focused on macroalgal transport in ballast water. To address this, we collected replicate samples of ballast water from 12 ships in two Mediterranean harbours (Naples and Salerno). Filtered samples were kept in culture for a month at Mediterranean mean conditions (18 degrees C, 12:12h LD, 60micromol photons m(-2)s(-1)). Fifteen macroalgal taxa were cultured and differed according to the geographic origin of the ballast water. Most of the cultured algae were widely distributed species (e.g. Ulva spp. and Acinetospora-phase). However, Ulva ohnoi Hiraoka and Shimada, described from Japan, was hitherto unknown in the Mediterranean Sea. We show for the first time that ballast water can be an important vector for the transport of microscopic stages of macroalgae and that this can be a vector for the introduction of alien species.     

Marine testing board for certification of ballast water treatment technologies

The proposed MTB is a process to expedite the implementation of international standards and regulations, and the subsequent testing, certification, and regulatory approval of new ballast water treatment ("control") technologies. This would expedite their acceptance in the global marketplace and reduce risks of shipowners following international regulation. The cost to test and evaluate and certify new ballast water treatment technologies for the global marketplace has been estimated to be less than US $1 per day per ship. It is time for the shipping industry, national regulatory bodies, and IMO to endorse the concept of the MTB and for the shipping industry to support a proactive cost-saving solution for sustainable shipping and protecting the environment from unwanted invasions of aquatic species with their potential negative impacts.     

Bacteriological examination of ballast water in Singapore Harbour by flow cytometry with FISH

In this study the concentrations of total bacteria, enterobacteria, Vibrio spp., and E. coli have been compared for ballast water samples taken from ships in Singapore Harbour. The cell concentrations were enumerated using FISH and flow cytometry. The data were highly variable, reflecting the many influences upon ballast water as it is utilized in the shipping industry. The concentration of bacterial species was determined as a proportion of the total concentration of cells for the ballast water sampled. For the ballast water sampled these concentrations were 0.67-39.55% for eubacteria, 0-2.46% for enterobacteria, 0.18-35.82% for Vibrio spp., and 0-2.46% for E. coli. Using FISH and flow cytometry, an informative determination of the bacterial hazards of ship ballast water can be made.     

Continuous flushing of contaminants from ballast water tanks

The transport of non-indigenous species (NIS) with ship ballast water is a major environmental problem. The International Maritime Organisation (IMO) have recommended that ballast tanks are flushed through with sea water to remove NIS contaminants. The flushing efficiency is studied using mathematical models and a scaled experimental model of a ballast tank. The density contrast between the ballast water and water used for flushing is important when the Froude number Fr(w)=U(w)/sqr rt|g(')|H < 1 (defined in terms of average horizontal flow U(w), reduced buoyancy g', and H the vertical dimension in the tank). When denser water is used to flush a ballast tank, from below, it efficiently displaces lighter ballast water; but flushing through with light water creates a buoyant gravity current which effectively short circuits part of the tank. When Fr(w)>1, the density contrast between the ballast water and water used for flushing is not important and flushing is controlled by a bulk Péclet number, Pe(w). For Pe(w)<1 perfect mixing occurs, while for Pe(w)>1 displacement flushing occurs. Laboratory experiments of flushing were performed using a model two-dimensional ballast tank employing dye attenuation to measure the whole concentration field and these experiments confirm the essential features of the mathematical models. The results of this study are discussed in the context of current IMO flushing protocols.     

Survey on germination and species composition of dinoflagellates from ballast tanks and recent sediments in ports on the South Coast of Finland, North-Eastern Baltic Sea

Cyst beds in ships and ports in Finland have previously been unstudied. Therefore, sediments from ships' ballast water tanks and four Finnish ports were sampled for dinoflagellate cysts and other phytoplankton. Untreated sediments were incubated at 10 degrees C and 20 degrees C in the local 6 psu salinity for 1, 4 and 7 days, and vegetative cells were examined with light and scanning electron microscope. Sediments were inhabited by various dinoflagellates, diatoms, chlorophytes, cyanophytes and small flagellates. Germinated dinoflagellates were found in 90% of ballast tanks and in all ports. Gymnodiniales spp. and Heterocapsa rotundata formed a major proportion of the proliferating dinoflagellate cells. One species, Peridinium quinquecorne, not previously reported from the Baltic Sea, was identified with SEM. The study emphasises that ships are potential transport vehicles for dinoflagellate cysts even in the low salinity Finnish waters, and small-sized dinoflagellates should be focused upon in ballast water studies.     

Ballast water as a vector of coral pathogens in the Gulf of Mexico: the case of the Cayo Arcas coral reef

The discharge of nutrients, phytoplankton and pathogenic bacteria through ballast water may threaten the Cayo Arcas reef system. To assess this threat, the quality of ballast water and presence of coral reef pathogenic bacteria in 30 oil tankers loaded at the PEMEX Cayo Arcas crude oil terminal were determined. The water transported in the ships originated from coastal, oceanic or riverine regions. Statistical associations among quality parameters and bacteria were tested using redundancy analysis (RDA). In contrast with coastal or oceanic water, the riverine water had high concentrations of coliforms, including Vibrio cholerae 01 and, Serratia marcescens and Sphingomona spp., which are frequently associated with “white pox” and “white plague type II” coral diseases. There were also high nutrient concentrations and low water quality index values (WQI and TRIX). The presence of V. cholerae 01 highlights the need for testing ballast water coming from endemic regions into Mexican ports.