Sack Lunch Seminar (SLS)

Many aspects of how natural phytoplankton communities change through time remain poorly understood, in large part because traditional organism-level sampling strategies are not amenable to high frequency, long duration application. To overcome aspects of this limitation, we developed the FlowCytobot series of automated submersible flow cytometers capable of rapid, unattended analysis of individual plankton cells for long periods of time. FlowCytobot and Imaging FlowCytobot use a combination of laser-based scattering and fluorescence measurements and video imaging of individual particles to enumerate and characterize cells ranging from picocyanobacteria to chaining-forming diatoms. When combined with automated processing and image classification, these observations make it possible to characterize taxonomic composition of plankton communities with unprecedented temporal resolution, ranging from hours to years. Multi-year time series from FlowCytobot and Imaging FlowCytobot are now being used to study bloom dynamics and community structure in US coastal waters. The high temporal resolution observations of single cell properties make it possible not only to characterize taxonomic composition and size structure, but also to quantify taxon-specific growth rates. Emerging results provide a wide range of insights including links between climate factors and interannual variability in seasonal blooms, decadal-scale shifts in community composition, ecologically important roles for taxon-specific parasites, and detection and characterization of harmful algal blooms.