Comparison of three techniques to evaluate the number of viable phytoplankton cells in ballast water after ultraviolet irradiation treatment

Casas-Monroy, Oscar; Chan, Po-Shun; Linley, Robert Dallas; Byllaardt, Julie Vanden; Kydd, Jocelyn; Bailey, Sarah A.

doi:10.1007/s10811-016-0798-3

Cited by 23 publications

(13 citation statements)

References 26 publications

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“…It has been used to enumerate cyanobacteria and diatom, raphidophyte, and dinoflagellate propagules from soils and sediments (Imai et al 1986 ; Othman and Wollum 1987 ; An et al 1992 ; Itakura et al 1997 ; Harris et al 1998 ; McQuoid 2002 ) and to estimate the abundances of difficult-to-preserve subpopulations within natural communities of phytoplankton (Knight-Jones 1951 ; Throndsen 1978 ; Furuya and Marumo 1983 ; Jochem 1990 ; Throndsen and Kristiansen 1991 ; Backe-Hansen and Throndsen 2002 ; Andersen and Throndsen 2003 ; Cerino and Zingone 2006 ; reviewed recently by Cullen and MacIntyre 2016 ). More recently, it has been used to estimate viability after UVC treatment (Oemcke et al 2004 ; First and Drake 2014 ; Casas-Monroy et al 2016 ; Chaudhari et al 2015 ; Wright and Welschmeyer 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Enumerating viable phytoplankton using a culture-based Most Probable Number assay following ultraviolet-C treatment

et al. 2017

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Ballast water management systems (BWMS) must be tested to assess their compliance with standards for the discharge of organisms, for example in the ≥ 10- and < 50-μm size category, which is dominated by phytoplankton. Assessment of BWMS performance with the vital stains fluorescein diacetate + 5-chlorofluorescein diacetate, required by regulations in the USA, is problematic in the case of ultraviolet-C (UVC) radiation. This is because UVC targets nucleotides—and thus reproduction, hence viability—rather than membrane integrity, which is assayed by the stains. The Serial Dilution Culture-Most Probable Number (SDC-MPN) method, long used to enumerate fragile phytoplankton from natural communities, is appropriate for counting viable phytoplankton. We developed QA/QC “best practice” criteria for its application as a robust and repeatable assay of viable cells in cultures of phytoplankton before and after experimental treatment, then constructed dose-response curves for UVC-induced loss of viable cells in 12 species of phytoplankton from seven divisions. Sensitivity to UVC, expressed as the dose required to reduce viability by 99%—the criterion for type approval of treatment systems—varied more than 10-fold and was not correlated with cell size. The form of the dose-response curves varied between taxa, with most having a threshold dose below which there was no reduction in viability. Analysis of the patterns of growth indicates that if recovery from treatment occurred, it was complete in 1 or 2 days in > 80% of cases, long before the assays were terminated. We conclude that the SDC-MPN assay as described is robust and adaptable for use on natural phytoplankton.

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Section: Introductionmentioning

confidence: 99%

Enumerating viable phytoplankton using a culture-based Most Probable Number assay following ultraviolet-C treatment

et al. 2017

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“…Historically, ballast water sampling methods included Van Dorn bottles (Klein et al 2009;Roy et al 2012;Casas-Monroy et al 2016) and non-submersible pumps (Murphy et al 2002) with connected tubing at different depths. The Van Dorn bottle has been used to collect samples from a given location and depth(s) throughout the water column in the tank.…”

Section: Discussionmentioning

confidence: 99%

“…Samples were processed immediately following collection for enumeration of live phytoplankton using FDA and epifluorescence microscopy (see Adams et al 2014;Casas-Monroy et al 2016;Vanden Byllaardt et al 2017). A 5-mL aliquot was removed from the 250 mL concentrated sample using a 5-mL pipette after mixing the sample by gentle inversion (5×).…”

Section: Live Countsmentioning

confidence: 99%

Improving estimation of phytoplankton abundance and distribution in ballast water discharges

2020

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With the International Maritime Organization's (IMO) International Convention for the Control and Management of Ships' Ballast Water and Sediments now in force, determining abundance and distribution of phytoplankton inside ballast tanks is critical for successful ballast water management, particularly when assessing compliance. The relationship between the abundance and distribution of cells was examined to obtain the best representative sample of the entire phytoplankton community in ballast tanks, comparing three ballast water sampling techniques including in-line, in-tank, and Van Dorn bottle methods. Lloyd's index, D y , and Gini index were applied to compare methods of sample collection and determine representativeness of samples and performance of sampling methods. Phytoplankton abundance trends from live microscopy counts using fluorescein diacetate (FDA) were also compared to those using a FlowCAM on preserved samples. The phytoplankton community showed a patchy distribution inside the ballast tank and this trend was observed across all voyages. The estimated marginal mean analysis showed that in hypothetical conditions (e.g., 702 m 3 of water in ballast tank and phytoplankton whole-tank abundance of 19,522 cells), the difference among the three methods was small. Conversely, statistical analysis performed on empiric abundances using a negative binomial regression model determined that the volume discharged during sampling of ballast water has an effect on the number of cells collected on a given voyage. Results of this study also confirmed that the in-line method may be a better method at collecting phytoplankton samples from ballast tanks than the in-tank or Van Dorn method, regardless of the time at which samples are collected. Finally, the number of living cells and the number of preserved cells showed similar trends for most of the voyages, despite fewer samples analyzed using FDA.

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“…Data collected during a parallel study showed that UV transmittance (UVT) values for Hamilton Harbour water ranged between 80.4% and 84.6% during summer and between 88.0% and 89.6% during winter (see Casas-Monroy et al 2016). UVT measures the amount of light that passes through a natural water sample compared with that which passes through a pure water sample (i.e., distilled water).…”

Section: Discussionmentioning

confidence: 99%

“…In particular, we confirmed that pH measured between 5 and 7 to ensure the production of the most effective compounds of free chlorine (HOCl) during the experiments (Delacroix et al 2013). Enumeration and taxonomic identification of collected phytoplankton cells were conducted as part of a simultaneous study (see Casas-Monroy et al 2016). Briefly, 100 mL of sample water were preserved with Lugol's acid, a total volume of 50 mL was put in a settling column for 24 h following the Utermöhl technique (Utermöhl 1958), and intact cells were counted using a Nikon AZ100 inverted microscope.…”

Section: Phytoplankton Collectionmentioning

confidence: 99%

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

Casas-Monroy

Byllaardt

Bradie

et al. 2019

Can. J. Fish. Aquat. Sci.

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Chlorine efficacy as a biocide for ballast water treatment was investigated under cold-and warm-water temperatures across winter and summer seasons. Freshwater phytoplankton samples were collected and acclimated under in situ environmental conditions ranging from 2 to 22°C. Samples were exposed to seven chlorine treatments (from 0.02 to 5.0 ppm), in addition to a control (0.0 ppm). Free-chlorine concentrations, phytoplankton abundance, and photosynthetic efficiency were measured up to 48 h following treatment. After 4 h of treatment at concentrations less than 0.22 ppm, phytoplankton densities were reduced by more than 50%, without cell resurgence. Similar reduction was recorded immediately after exposure when chlorine concentrations were higher than 3.0 ppm. After 8 h, free chlorine neared 0.0 ppm for initial chlorine concentrations below 1.2 ppm, irrespective of temperature regime. Winter phytoplankton exhibited slightly lower mortality to chlorine exposure regardless of the temperature, although they also exhibited lower photosynthetic efficiency. Despite a general absence of significant effect of temperature on the chlorine decay, our results suggest that higher doses of chlorine or longer exposure times may be required during winter to achieve full treatment effect. Tests at large scales are needed to further confirm these findings.Résumé : L'efficacité du chlore comme biocide pour le traitement de l'eau de ballast a été étudiée dans des conditions d'eau chaude et froide, en été et en hiver. Des échantillons de phytoplancton d'eau douce ont été prélevés et acclimatés dans des conditions ambiantes allant de 2°C à 22°C. Les échantillons ont été exposés à sept traitements au chlore (de 0,02 ppm à 5,0 ppm), en plus d'un traitement témoin (0,0 ppm). Les concentrations de chlore libre, ainsi que l'abondance et le rendement photosynthétique du phytoplancton ont été mesurés jusqu'à 48 h après le traitement. Après 4 h de traitement à des concentrations de moins de 0,22 ppm, les densités de phytoplancton avaient baissé de plus de 50 % sans résurgence de cellules. Une baisse semblable a été observée immédiatement après l'exposition quand les concentrations de chlore étaient supérieures à 3,0 ppm. Après 8 h, la concentration de chlore libre s'approchait de 0,0 ppm pour des concentrations initiales de chlore inférieures à 1,2 ppm, peu importe le régime thermique. Le phytoplancton hivernal présentait une mortalité légèrement plus faible découlant de l'exposition au chlore, quelle que soit la température, mais son rendement photosynthétique était aussi plus faible. Malgré l'absence générale d'effet significatif de la température sur la décomposition du chlore, nos résultats donnent à penser que des doses plus élevées de chlore ou de plus longues durées d'exposition pourraient être nécessaires durant l'hiver pour que le traitement soit pleinement efficace. Des essais à grande échelle sont nécessaires pour confirmer ces résultats. [Traduit par la Rédaction]

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Comparison of three techniques to evaluate the number of viable phytoplankton cells in ballast water after ultraviolet irradiation treatment

Cited by 23 publications

References 26 publications

Enumerating viable phytoplankton using a culture-based Most Probable Number assay following ultraviolet-C treatment

Enumerating viable phytoplankton using a culture-based Most Probable Number assay following ultraviolet-C treatment

Improving estimation of phytoplankton abundance and distribution in ballast water discharges

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

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