The Imaging Flow Cytobot and the Environmental Sample Processor: New Tools that will shape our understanding of harmful algal blooms

Harmful algal blooms (HABs) are proliferations of phytoplankton and macroalgae that detrimentally affect natural resources and human health. Some HABs produce toxins that cause a wide range of human health impacts from rashes and asthma-like symptoms to respiratory arrest and death. Therefore, understanding how HAB organisms grow is vital to designing effective strategies to mitigate their impact. A significant technical challenge for the study of HABs has been to distinguish HAB from other morphologically similar algal species. This issue has been addressed through the development of two new oceanographic instruments, the Imaging Flow Cytobot (IFCB) and the Environmental Sample Processor (ESP). These machines use different approaches to estimate the abundance of HAB species in situ while also monitoring other important environmental variables like salinity and temperature. The IFCB captures and classifies images of individual phytoplankton cells into distinct morphological groups while the ESP specifically identifies 5 target organisms through ribosomal probes. Documenting cytokinesis, or cellular division, in Alexandrium tamarense has been the particular focus of our research. Images rendered by the IFCB can quantify the ratio between single to dividing cells in a sample through time. If this ratio is a good estimator for A. tamarensegrowth, we hope to incorporate the ESP to recognize DNA abundance at different mitotic stages, furthering our capacity to monitor toxic blooms. With both image and DNA data, this ongoing project can transform existing HAB assays, allowing researchers the ability to identify and monitor HABs with new precision.