An Embedded Cytomete 1 of 3 2022

he photosynthetic microbes ? the phytoplankton ? generate about 50% of the oxygen and organic matter produced on Earth each year and serve as the base of marine food webs. Flow cytometers are essential oceanographic instruments that rapidly and accurately measure the abundance, size and fluorescent characteristics of individual phytoplankton cells. For example, flow cytometry led to the discovery of Prochloroccocus, the most abundant photosynthetic organism on Earth. However, thirty-seven years after the first description of a flow cytometer designed specifically for the measurement of phytoplankton in the field, the complexity of flow cytometry, and the multi-parametric data it produces continues to be an obstacle to its evolution towards common use as an oceanographic field instrument. PipeCyte is a miniature, low-power flow cytometer instrument that was designed to perform autonomous measurements of 0.5-10 µm diameter phytoplankton while deployed on autonomous oceanographic measurement platforms. In this first deployment project, the PipeCyte instrument will be immersed at depths of up to 100 meters while tethered to a surface buoy. A surface buoy is a low-cost platform that is simple to deploy from a research vessel. In this project, several buoy deployed PipeCyte instruments will be released in the open ocean to perform measurements of the phytoplankton community at multiple depths. These measurements will provide an unprecedented view of the relation between environmental features and phytoplankton communities along the water column.