The Design and Optimization of Optical Systems for the Detection and Characterization of Phytoplankton

Phytoplankton are among the smallest organisms found in marine and freshwater ecosystems. Despite their small size, phytoplankton play a vital role in sustaining life on Earth as primary producers. Through oxygenic photosynthesis phytoplankton are also responsible for large scale carbon fixation and oxygen production. The distribution of phytoplankton in a given water resource can exhibit a high degree of variability across time and space, and this is in large part due to their varying sensitivities to environmental conditions such as resource availability and grazing by predator organisms. As such, phytoplankton community structure is widely used as an investigative tool for assessing the general health of aquatic ecosystems. Adequate monitoring of these systems can require a variety of techniques, like satellite remote sensing, grab sampling of water for ex situ analysis, or in situ sensing. These techniques all have some form of inherent disadvantage associated with their use, namely spatial, temporal, or taxonomic resolution – though the advantages of one technique will often offset the disadvantages of another. Further, interpretation of results from monitoring efforts is difficult to achieve without controlled laboratory analyses aimed at characterizing phytoplankton and their unique responses to a changing environment. This work will discuss an effort to design and optimize novel sensing and sampling technology that facilitates higher efficiency and accuracy with respect to the monitoring of phytoplankton in the field. Additional work was done to develop a polarized fluorescence microscope system for the characterization of nonmotile phytoplankton, specifically the harmful algal bloom forming cyanobacterium Microseira wollei, which can facilitate a better understanding of biogeochemical cycles that govern bloom dynamics and advance work in areas such as predictive modelling and remote sensing.