Comparing flow cytometry and microscopy in the quantification of vital aquatic organisms in ballast water

Abstract

The ability to quantify vital aquatic organisms in the 2-50 µm size range was compared between five different flow cytometers and several different microscopes. Counts of calibration beads, algal monocultures of different sizes as well as organisms in a Wadden Sea sample were compared. Flow cytometers and microscopes delivered different bead concentrations. These differences between the instruments became larger for algal monocultures and were even higher for the Wadden Sea sample. It was observed that the concentration differences were significant between flow cytometer and microscope counts, and that this difference increased with the size of the objects counted. Microscope counts were more accurate for larger (50 µm) objects because cytometers struggled with bigger particles that clogged the instruments. Contrary to microscopy, the flow cytometers were capable of accurately enumerating cultured cells in the 2-10 µm size range and cells in the lower size range of the 10-50 µm size class. Flow cytometers were also well-suited to assess low abundance samples due to their ability to process larger volumes than microscopes. The results were used to indicate which tools are suitable for ballast water monitoring: flow cytometry is a suitable technology for an indicative and real time analysis of ballast water samples whilst only microscopy would be robust enough for detailed taxonomical analyses.

Interoperable vocabulary for marine microbial flow cytometry

“…A second reason for building such a vocabulary is the continued development of machine learning and other techniques for interpreting the ever-growing number of studies involving multiparametric FCM analysis of marine samples, especially with the increasing use and diversity of autonomous high frequency sensors. Indeed, inter-laboratory data analysis based on manual classification of the FCM groups can be affected by strong variability, especially for the dimmest and the least concentrated groups such as the RedPicoProk, the HsNano or the RedMicro and OraMicro groups (Fuchs et al, 2022), and for data generated by different instruments (Peperzak et al, 2020). Annotation of groups based on a consensus definition will facilitate the process of building the workflow from the original dataset to the interoperable database.…”

The Role of Vessel Biofouling in the Translocation of Marine Pathogens: Management Considerations and Challenges

“…For many micro-organisms, the effect of UV irradiation may not be immediate, raising the issue of organism viability (i.e., treatment efficacy). This issue has introduced a variety of complications when determining the efficacy of BWMS (First and Drake, 2014;Batista et al, 2017;Peperzak et al, 2020). For example, damage to organisms, in certain cases, may be repairable (e.g., Zimmer and Slawson, 2002).…”

Methodology for Phytoplankton Taxonomic Group Identification towards the Development of a Lab-on-a-Chip

“…Local or regional authorities routinely perform this task by collecting phytoplankton and shellfish samples, analysing their toxicity and regulating the safe harvesting of seafood. The available methods for phytoplankton identification and quantification are based on optical and electronic microscopy, flow cytometry, image analysis, pigment analysis through high performance liquid chromatography (HPLC) and molecular methods [7,8]. However, these tasks can be expensive, time or reagent consuming, and require highly trained personnel, which can be limiting for in situ and real time HAB monitoring [9].…”