Characterization of reflectance spectra of phytoplankton cultures: implication of remote sensing of HABs

In a pilot project, spectral reflectance of two classes of micro algae were measured as a first step in determining the major component of algal blooms in optically complex coastal waters. Representative of Dinophyta, dinoflagellate Prorocentrum minimum, and Cyanophyta, cyanobacteria Synechococcus sp. were grown in cell cultures. Optical measurements were taken of the cultures, as well as the progressive dilution and of mixed cell cultures. Cell counts and samples of high pressure liquid chromatography (HPLC) were collected as well. These data were collected from logarithmic growth phases of both cultures. Derivative analysis was one method used to analyze reflectance spectra of the two cultures. Predominant pigments from HPLC were zeaxanthin and phaeophytin a for Syncecoccus, while peridinin and diadinoxanthin predominated for Prorocentrum. Derivative analysis enhanced absorption curves for many pigments, but is not as useful for broad Gaussian features. Spectral results from diluting and mixing cultures will be presented as well as analysis results using archived field survey data.