Roelke, D. L. Texas A&M University, Wildlife and Fisheries Sciences, droelke@wfscgate.tamu.edu
Kennedy, C. L. Naval Research Laboratory, Code 7331,
Weidemann, A. D. Naval Research Laboratory, Code 7331,

 
SIGNAL TO NOISE RATIO AND SPECTRAL RESOLUTION REQUIREMENTS OF DISCRIMINANT AND FOURTH-DERIVATIVE ANALYSIS OF PHYTOPLANKTON ABSORPTION SPECTRA
 
Future management efforts aimed at inhibiting harmful algal blooms will require extensive temporal and spatial monitoring of phytoplankton community composition. A cost-effective approach to delineating phytoplankton community composition may be through analysis of absorption spectra, measured in-situ with instruments deployed on moorings or by remote sensing. Classification techniques relying on absorption spectra include discriminant and fourth-derivative analysis. We investigated how well these techniques performed theoretically at varied signal to noise ratio and spectral resolution representative of a new absorption and attenuation instrument, called HiStar, deployed in a natural environment. Our findings suggest that discriminant analysis of absorption spectra is a highly useful technique for classification of noxious bloom-forming dinoflagellate species at signal to noise ratios as low as 17.2. Furthermore, discriminant analysis of absorption spectra does not require high-spectral data. The current noise level in the HiStar (1 x 10-2 m-1), however, is ~28-fold too high to allow correct classification of a noxious dinoflagellate bloom in its early stages. Improvements to the discriminant analysis (e.g., inclusion of scatter properties) or to the HiStar (e.g., increasing the pathlength of the flow cell) must be accomplished before this technique becomes useful for management applications. Fourth-derivative analysis of absorption spectra, also a useful classification technique and a possible approach to assess physiological state of some algae, required at least 4 nm spectral resolution for assessment of chlorophyll a and b. The spectral resolution of HiStar (3.3 nm) meets this requirement.
 
Day: Wednesday, Feb. 3
Time: 11:00 - 11:15am
Location: Sweeney Center
 
Code: SS08WE1100S