Promising approaches for ballast water sample collection and analysis have been developed, but require further study in the field to examine their utility for compliance monitoring. To address this gap, a voyage was undertaken by 20 international researchers on board the RV Meteor from June 4-15, 2015. During this time 28 trials were conducted to evaluate three ballast sampling devices (plankton net and 2 sampling skids) and a number of analytic devices.
Water samples were collected using paired sampling devices and analysed in parallel by all analytic methods to determine whether results were similar between devices and whether quick, indicative methods offer comparable results to standard, time-intensive testing methods (e.g. microscopy) and high-end scientific approaches.
For sample collection, some differences were observed in the number of viable organisms collected by the various sampling devices (net, sampling skids in open and closed configurations), but these differences were not consistent across size classes and, in many cases, there was no significant difference between samples collected with a net or with a skid.
For sample analysis, several promising indicative methods were identified that showed high correlation with microscopy results but allow much quicker processing. This study is the first to concurrently test a large number of analytic tools and multiple sampling devices under operational conditions. Results are useful to identify the merits of each method and can serve as a basis for further improvement and development of these tools and methodologies for compliance.
Some snapshot of this report is diaplyed at above pictures:
Figure 7 in page 43: Scatterplots of each analytic tool for the 10-50 μm size class versus total microscopy counts. Red points are used to distinguish samples that were treated with the ballast water management system. Grey points indicate values that were below the detection range of the Hach BW680 and were plotted assuming the minimum detection limit. All values are standardized to raw sample concentration to account for any concentrations performed by individual researchers. The solid line indicates the line of best fit found using Deming regression and the dashed line indicates the 1:1 line for devices reporting values in the same units. The Pearson correlation coefficient for each plot is indicated above the figure. Note that coefficients should not be directly compared since plots differ in the number of data points. The shaded rectangles indicate a region where no data was available for a given technique
The experiment compared the measurement values of ballast water in 3 different stages between the newly developed bbe 10cells instrument and the results of a FDA stains counting method used by the MERC and ACT teams. In addition, a dilution series was performed in order to demonstrate the capabilities of the new approach and the new device.
On Day 1, the filling day of two ballast water tanks, MERC determined 2,822 (standard deviation 1,098 cells/ml) living algae per ml in the tank, bbe 10cells identified 2,959 cells/ml (standard deviation 240 cells/ml). The measurement procedure including the filtration using bbe 10cells needs less than 4 minutes and no chemicals are needed. Three days later, an integrated sample from emptying the first tank was taken and cell numbers determined, resulting in 569 cells/ml (stain counts) vs. 330 cells/ml (bbe 10cells); after 7 days the second tank release led to 51 cells/ml FDA stain counts vs. 95 cells/ml with bbe 10cells.
This result can be affected by filter properties and stain evaluation methods. A dilution series of the third sample showed a detection limit of the bbe 10cells of approximately 1 cell/ml. This is far below the required 10 cells/ml.
The International Convention for the Control and Management of Ships Ballast Water and Sediments, 2004 (BWM Convention) of the International Maritime Organization (IMO) entered into force on 8 September 2017, aiming to prevent the spread of aquatic non-indigenous species. All ships must follow the ballast water performance standard (D-2 standard) of the BWM Convention at the latest by 8 September 2024.
The Finnish Transport and Communications Agency (Traficom), the port State control authority in Finland may conduct ballast water sampling and indicative analyses during inspections in the future. The aim of the study commissioned by Traficom was to test four indicative analysis devices for port State control monitoring purposes.
The study equally aimed to provide useful information on various compliance monitoring related subjects for the experience-building phase of the IMO. The study was conducted for Traficom by the Finnish Environment Institute (SYKE).
The tested indicative methods were Adenosinetriphosphate (ATP), modified Pulse Amplitude Modulation (PAM) fluorometry, Single Turnover Active Fluorometry (STAF) and Motility and Fluorescence Assay (MFA). The sampling events were conducted in October and November, 2018, on two Finnish ships that have ballast water treatment systems installed on board.
The indicative analysis results were compared to detailed laboratory analyses that were conducted for the same samples with fluorescein diacetate (FDA) and epifluorescence microscopy method. All devices tested were considered portable, reasonably priced and manageable for port state control officers to use.
There was a clear difference in the estimated viable organism concentrations between the treated and untreated water samples using each device, showing their capability to differentiate between untreated and treated waters. The devices had difficulties in referring their results to the compliance limits of the D-2 standard.
As these compliance limits are defined as number of viable organisms per volume of interest, especially the ATP method does not convert the recorded bulk ATP values into viable organism concentrations. In addition, methods that measure viability only from photosynthetically active phytoplankton cells (PAM and STAF) might be unable to detect compliance status for oligotrophic open sea samples, where these organisms can be rarely present. As the devices are designed to be indicative, it would be more reasonable if the IMO provided indicative compliance limits for the D-2 standard separately.
The present D-2 standard compliance limits are inapplicable when compared to the method-specific thresholds of the indicative analysis devices and their accuracy.