Many commercial ships will soon begin to use treatment systems to manage their ballast water and reduce the global transfer of harmful aquatic organisms and pathogens in accordance with upcoming ...International Maritime Organization regulations. As a result, rapid and accurate automated methods will be needed to monitoring compliance of ships' ballast water. We examined two automated particle counters for monitoring organisms ≥50μm in minimum dimension: a High Resolution Laser Optical Plankton Counter (HR-LOPC), and a Flow Cytometer with digital imaging Microscope (FlowCAM), in comparison to traditional (manual) microscopy considering plankton concentration, size frequency distributions and particle size measurements. The automated tools tended to underestimate particle concentration compared to standard microscopy, but gave similar results in terms of relative abundance of individual taxa. For most taxa, particle size measurements generated by FlowCAM ABD (Area Based Diameter) were more similar to microscope measurements than were those by FlowCAM ESD (Equivalent Spherical Diameter), though there was a mismatch in size estimates for some organisms between the FlowCAM ABD and microscope due to orientation and complex morphology. When a single problematic taxon is very abundant, the resulting size frequency distribution curves can become skewed, as was observed with Asterionella in this study. In particular, special consideration is needed when utilizing automated tools to analyse samples containing colonial species. Re-analysis of the size frequency distributions with the removal of Asterionella from FlowCAM and microscope data resulted in more similar curves across methods with FlowCAM ABD having the best fit compared to the microscope, although microscope concentration estimates were still significantly higher than estimates from the other methods. The results of our study indicate that both automated tools can generate frequency distributions of particles that might be particularly useful if correction factors can be developed for known differences in well-studied aquatic ecosystems.
•A High Resolution-LOPC and a FlowCAM were evaluated for ballast water monitoring.•Both instruments underestimated density compared to microscopy.•Size measurements can be affected by organism orientation and complex morphology.•Both tools might be particularly useful when working with a known community.
With the entry into force of the International Maritime Organization's International Ballast Water Management Convention in September 2017, ships have begun to install and operate onboard ballast ...water management systems (BWMS) to reduce the number of live organisms in ballast water. Scientific methods were developed to assess the effectiveness of BWMS at reducing the number of live organisms in ballast water. However, detecting low organism concentrations in treated ballast water is challenging when considering the small sample volume (6 mL) analyzed for organisms in the 10–50 μm size class. The volume analyzed can be increased by concentrating the sample prior to analysis, but it is important to assess the effects of the sample concentration method due to potential cell loss experienced during the concentration step. Therefore, laboratory experiments were conducted to assess the effects of a gravity filtration method to concentrate samples to a factor of 40:1. Experiments were conducted for both low and high organism abundances. For unpreserved samples at low organism abundances (∼10 cells mL−1), concentrated samples had on average 31% fewer live cells mL−1 than unconcentrated samples for four out of five experiments. At high organism abundances (≥ 120 cells mL−1), unpreserved concentrated samples had on average 55% fewer live cells than unconcentrated samples. Alternatively, with preserved samples at low organism abundances, concentrated samples had on average 4.5× more cells than unconcentrated samples. At high organism abundances, concentrated samples had on average 6.4× more cells than unconcentrated samples. Differences were also observed between preserved and unpreserved samples. These findings can help to improve ballast water monitoring procedures and BWMS assessments, addressing a critical challenge to maritime environmental protection.
•Concentration by gravity filtration led to cell loss in live phytoplankton samples.•Alternate concentration methods should be explored to mitigate cell loss.•Concentrating had different effects on live and preserved samples.•Concentrating samples is important to improve precision at low abundances.•Counting six subsamples improved precision in low abundance samples.
Ballast water is a leading pathway for the global introduction of aquatic nonindigenous species. Most international ships are expected to install ballast water management systems (BWMS) by 2024 to ...treat ballast water before release. This study examines if ballast water discharges managed by BWMS are meeting standards for organisms ≥50 μm in minimum dimension (i.e., <10 organisms per m3; typically zooplankton). Representative samples of ballast water were collected from 29 ships (using 14 different BWMS) arriving to Canada during 2017–2018. Fourteen samples (48 %) had zooplankton concentrations clearly exceeding the standard (ranging from 18 to 3822 organisms per m3). Nonetheless, compared to earlier management strategies, BWMS appear to reduce the frequency of high-risk introduction events. BWMS filter mesh size was an important predictor of zooplankton concentration following treatment. Greater rates of compliance may be achieved as ship crews gain experience with operation and maintenance of BWMS.
•Ballast water is a main pathway for introduction of aquatic nonindigenous species.•Ships are using new ballast water management systems (BWMS) to treat ballast water.•Nearly 50 % of ballast water samples exceed treatment standards after using BWMS.•However, the frequency of high-risk introductions has been dramatically reduced.
Abstract
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.
The International Maritime Organization (IMO) has set limits on allowable plankton concentrations in ballast water discharge to minimize aquatic invasions globally. Previous guidance on ballast water ...sampling and compliance decision thresholds was based on the assumption that probability distributions of plankton are Poisson when spatially homogenous, or negative binomial when heterogeneous. We propose a hierarchical probability model, which incorporates distributions at the level of particles (i.e., discrete individuals plus colonies per unit volume) and also within particles (i.e., individuals per particle) to estimate the average plankton concentration in ballast water. We examined the performance of the models using data for plankton in the size class ≥10μm and <50μm, collected from five different depths of a ballast tank of a commercial ship in three independent surveys. We show that the data fit to the negative binomial and the hierarchical probability models equally well, with both models performing better than the Poisson model at the scale of our sampling. The hierarchical probability model, which accounts for both the individuals and the colonies in a sample, reduces the uncertainty associated with the concentration estimation, and improves the power of rejecting the decision on ship's compliance when a ship does not truly comply with the standard. We show examples of how to test ballast water compliance using the above models.
•Plankton distribution has been previously modeled as Poisson and negative binomial distributions.•We propose a hierarchical probability model to account for the presence of colonial species.•Performance of the different models was tested using data from ballast water.•The proposed model has narrower confidence intervals and greater statistical power.•Results are useful for monitoring compliance with ballast water discharge standards.
The unintentional release of aquatic nonindigenous species (NIS) via ballast water has long been recognized as a primary vector of biological invasions. To reduce the risk of ballast-mediated ...invasions, the International Maritime Organization (IMO) will direct ships to meet standards regarding the maximum number of viable organisms discharged in ballast water, with most ships expected to install ballast water management systems (BWMSs). Currently, filtration + ultraviolet (UV) irradiation is utilized as a common BWMS. There are issues, however, with enumerating viable phytoplankton after treatment at the low UV doses used onboard ships because the physiological effect occurs at the DNA level—organisms are reproductively sterilized but may remain alive for hours or days after treatment. The objective of this study is to examine three techniques to measure the number of viable phytoplankton cells following filtration + UV treatment: pulse amplitude modulation (PAM) fluorometry, epifluorescence microscopy using fluorescein diacetate (FDA) stain, and the serial dilution culture most probable number (MPN) method. PAM and staining techniques demonstrated similar patterns of phytoplankton reduction after UV irradiation. After 14 days, the MPN method confirmed viability of treated samples in enriched culture medium incubations and may be used to indicate potential recovery of damaged cells (i.e., “re-growth”). All cells that survived treatment and showed detectable growth after 14 days of incubation were smaller than 10 µm, as determined by microscopy. Combinations of direct and/or indirect measurements and culture-based methods might be the best solution to improve detection strategies and eliminate nonindigenous species.
To prevent new ballast water-mediated introductions of aquatic nonindigenous species (NIS), many ships will soon use approved Ballast Water Management Systems (BWMS) to meet discharge standards for ...the maximum number of viable organisms in ballast water. Type approval testing of BWMS is typically conducted during warmer seasons when plankton concentrations are highest, despite the fact that ships operate globally year-round. Low temperatures encountered in polar and cool temperate climates, particularly during the winter season, may impact treatment efficacy through changes in plankton community composition, biological metabolic rates or chemical reaction rates. Filtration+UV irradiance is one of the most common ballast water treatment methods, but its effectiveness at low temperatures has not been assessed. The objective in this study was to examine the efficacy of filtration+UV-C irradiation treatment at low temperatures for removal or inactivation of phytoplankton and zooplankton populations during simulated ballast water treatment. Organisms from two size classes (≥10 to <50μm and ≥50μm) were identified and enumerated using microscope and culture techniques. The response of organisms in both size categories to UV-C irradiation was evident across a range of temperatures (18°C, 12°C and 2°C) as a significant decrease in concentration between controls and treated samples. Results indicate that filtration+UV-C irradiation will be effective at low temperatures, with few viable organisms ≥10 to <50μm recorded even 21days following UV exposure (significantly lower than in the control treatment).
•Effectiveness of filtration+UV irradiance is assessed at low temperatures.•Zooplankton concentrations in treated samples were significantly reduced.•The percent reduction was more variable for phytoplankton than for zooplankton within and across temperatures.•Final concentrations for both phytoplankton and zooplankton were compliant with proposed discharge standards.
Just medicare Flood, Colleen M
Just medicare,
2006, 20060331, 2000, 2006-01-01
eBook
Just Medicareillustrates that legal scholars can also contribute to the issue of how to allocate scarce health resources by determining what constitutes fair processes for decision-making, and by ...challenging unjust processes.
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