Poster Session 2, Tuesday, October 4, 10:40–12:40
First hyperspectral backscattering measurements of phytoplankton monocultures with the Phytoplankton Light Scattering Instrument (PPLS) prototype
Satellite remote sensing reflectance (Rrs) is related to the ratio of backscattering and absorption processes in the ocean. In phytoplankton, absorption is controlled by pigments and is assumed to be constant within taxonomic groups. Unlike absorption, backscattering is related to the cell shape, size, and index of refraction, which can vary within taxonomic groups and has not been as well documented or explored. Previous studies of backscattering by phytoplankton have been restricted to limited multispectral measurements due to the lack of a hyperspectral backscattering sensor. We present preliminary data from the Phytoplankton Light Scattering Instrument (PPLS) prototype, capable of measuring hyperspectral backscattering in laboratory settings. The goal was to determine whether hyperspectral backscattering can be used to distinguish toxic from non-toxic phytoplankton species that share similar pigment composition. Hyperspectral absorption and backscattering measurements of six dinoflagellate species monocultures (including HAB species e.g. Akashiwo sanguinea, Karenia brevis, and Karlodinium veneficum) were taken and used to reconstruct Rrs spectra using the relationship between the two processes and Hydrolight software. Preliminary results with Alexandrium ostenfeldii and a Scrippsiella species suggest that 1) even though their pigment composition and absorption spectra are similar, their backscattering spectra are different, indicating that backscattering is a potential parameter to distinguish them 2) differences in concentration did not alter the backscattering spectra. Challenges to this process include managing the fluorescence signal and finding a suitable method to quantify differences in spectral shape. The results of this project have implications for upcoming hyperspectral satellite missions.
Sara Rivero-Calle, University of Georgia, [email protected]
Alan Holmes, SBIG Industries, [email protected]
Catharina Alves-de-Souza, University of North Carolina at Wilmington’s Algal Resource Collection Center, [email protected]
Aimee Neeley, National Aeronautics and Space Administration (NASA), [email protected]