Studying Marine Zooplankton Communities with FlowCam:
A Conversation with Kathryn Cook, PhD
Zooplankton have fascinated scientists in the field of marine ecology for many years. Changes in the structure of marine zooplankton communities are indicators of environmental and anthropogenic impacts on our water systems; therefore, studying these small aquatic microorganisms is important. We recently spoke with zooplankton biologist and pelagic biogeochemist Dr. Kathryn Cook, PhD, a FlowCam user since 2017, to learn how she's been using the FlowCam Macro instrument to advance her research. FlowCam is a flow imaging microscope that images particles and organisms in flow. FlowCam Macro, designed to analyze larger organisms up to 5 mm in size, is ideally suited for the study of zooplankton.
How has FlowCam Macro contributed to your zooplankton research?
Much of my research focuses on the size and quantity of organisms within rough taxonomic groups rather than on identifying which species are present. FlowCam provides a variety of size measurements for each particle, allowing us to construct size spectra of plankton communities and convert from biovolume to biomass for each individual particle instead of applying a conversion factor based on an average particle.
We use FlowCam Macro to analyze preserved zooplankton samples quickly and obtain size and rough taxonomic information. I use a standard, size-based classification template to sort my sample into rough-size categories, effectively sorting organisms into approximate taxonomic groups. Then I manually sort the ones that need to be reclassified. The automation possible with FlowCam has been a tremendous time saver.
Prior to FlowCam, what method were you using?
Before FlowCam, I used a microscope to examine zooplankton and phytoplankton. This would take at least half a day per sample, much longer if I needed to measure the organisms using an eye-piece graticule, and even then, I could only measure the length and width of the organisms.
FlowCam greatly reduced analysis time, from days to minutes, and provided me with highly resolved images and morphological data that helped me differentiate between living and dead cells and perform taxonomic classification. Additionally, FlowCam provides me with a digital record of the sample and how the organisms were classified.
How has FlowCam Macro improved your workflow?
FlowCam is a great teaching tool and has streamlined our workflow by supporting my ability to accommodate more undergraduate and master’s projects in my laboratory. Students can conduct analyses independently, and I can easily check their work with less subjectivity than comes with manual microscopy. Because of this, we have increased confidence in the data.
FlowCam provides us with a digital record of our samples, which not only reduces the physical space we need in our lab to store preserved zooplankton samples but also allows us to perform zooplankton sample classification analyses at our leisure in the comfort of our office (or living room!). Plus, it is far easier to train someone to run a sample through FlowCam than to identify plankton samples using a microscope.
Dr. Cook is pictured here with a student on a recent cruise.
Dr. Cook currently works at the University of Exeter, where her research focuses on how climate change affects zooplankton physiology and community structure and how this will affect biogeochemical processes and ecosystem functioning in the world’s oceans. If you'd like to learn more, download the case study.
