CytoSub: the under water flow cytometer

Waterproof flow cytometers for submerged use in sea, lakes and ponds

CytoSub’s are submersible versions of CytoSense: the scan and imaging flow cytometer

  • CytoSub “subsurface” for near surface operation (2 m depth)
  • CytoSub “shallow” for operation in surface waters (20 m depth)
  • CytoSub “deep” to explore the photonic zone (200 m depth)

By their unique submersible design, the CytoSubs provide:

  • the most efficient method to obtain high definition high frequency data (microscopy level) from remote in-situ locations / stations and full photonic zone depths. No financial and logistic burden of taking samples to the lab.  No waiting – direct answers.
  • Reliable data and surprising images of phyto- and zooplankton, fresh and undamaged in their natural ecosystem in their natural aggregation state. No tampering with samples, plankton nets or fixation deforming species beyond recognition.
  • Upgrade surface and subsurface monitoring stations and underwater vehicles with single cell analysis & imaging power.

CytoSub offers new possibilities for a wide range of applications:

  • operational oceanography monitoring
  • coastal observing networks
  • lake and river in-situ monitoring
  • aquatics and ecosystem bio-engineering and restoration control
  • early warning for sensitive ecosystems, aquaculture & farming, drinking source water protection
  • depth profiling

 

CytoSub provides a new type of comprehensive data for these applications, for an unprecedented size range of particulate matter and organisms.

For example:

  • high resolution data on all types of particles for fluxes and balance, primary production, eutrophication and algal blooms, important for economic and recreational activities
  • high frequency microscope level particle and cell images and scans from remote in-situ locations.
  • detect and identify harmful algal blooms (HAB’s) like cyanobacterial blooms and notice emerging species before they start blooming (impossible by bulk-optical sensors).
  • Detect not only picoplankton, nanoplankton, microplankton, both phytoplankton & zooplankton and small mesozooplankton, but also aggregates and colonies.
  • study sediment transport with direct detection of suspended particulate matter (instead of FTU), from smallest nanometer sized particles to large mineral particles, aggregates and flocs, separate analysis of phytoplankton abundance and composition.
  • Detects also microplastics and even nanoplastics by light scattering in combimation with imaging
  • Provides data to link with observations from satellites: CytoSub-Data from a fixed insitu location (such as mounted in the CytoBuoy) is the most versatile and always-available ground/sea truth data for validation and interpretation of remote sensing products (alagal blooms, suspended particulate matter, water column light attenuation and chlorophyll concentration, phytoplankton composition).

Key specifications

Deep

Operates to 200 m water depth

Compact

Compact design for handling and mounting e.g. on frame or in buoy 

Cables

Marine cables for interactive control, data transmission and power supply

Battery

Low power use for battery operation (without cable)

Benchtop 

Easily convertible for benchtop use

Data capacity

Large data storage capacity in built-in computer

Control unit

Robust control unit for connection to computer/network and power

Autonomous

Internal system for long autonomous operation : particle filter, activated carbon, biocide and calibration beads dosing

Help Shape a High- Frequency Plankton Observation Guide

To support harmonisation across the community, Dr. Veronique Creach (Cefas) is developing a Terms of Reference (TOR) within the ICES Working Group on Phytoplankton and Microbial Ecology (WGPME): “Create a guide for determining consistent plankton observations at high frequency.”

High-frequency flow cytometry and imaging are increasingly used to characterise phytoplankton diversity, including community cell-size structure. This approach aligns with the GOOS-edited (2025) Essential Ocean Variable Specification Sheet and supports higher-order products such as Phytoplankton Functional Types. As autonomous, high-sampling deployments expand, shared best practices for
collection, measurement, and analysis are essential.

To support harmonisation across the community, we are developing a Terms of Reference (TOR) within the ICES Working Group on Phytoplankton and Microbial Ecology (WGPME): “Create a guide for determining consistent plankton observations at high frequency.”

Who we’re looking for: CytoBuoy users (any platform or configuration).
What to share: sampling workflows, calibration/QA approaches, processing pipelines, metadata practices, and lessons learned from autonomous/high-frequency deployments.
Why participate: help establish consistent methods and improve
comparability across datasets and regions.

If you use a CytoBuoy instrument and would like to contribute, please contact Dr Veronique Creach (veronique.creach@cefas.gov.uk) or Nicole Poulton (npoulton@bigelow.org). A brief note describing your instrument configuration and use case is enough to get started.