Graduation Year

2009

Document Type

Thesis

Degree

M.S.

Degree Granting Department

Marine Science

Major Professor

Kendra Daly, Ph.D.

Co-Major Professor

Luis Garcia-Rubio, Ph.D.

Keywords

Harmful algal bloom, Detection, Absorbance, Scattering, Optics

Abstract

Optical research has shown that Karenia brevis has distinct spectral characteristics, yet most studies have focused exclusively on absorption and chemical properties, ignoring the size, shape, internal structure, and orientation, and their effect on scattering properties. The application of a new spectral interpretation model to K. brevis is shown to provide characterization of unique spectral information, not previously reported, through the use of scattering and absorption properties. The spectroscopy models are based on light scattering and absorption theories, and the approximation of the frequency-dependent optical properties of the basic constituents of living organisms. The model uses the process of mathematically separating the cell into four components, while combining their respective scattering and absorption properties, and appropriately weighted physical and chemical characteristics. The parameters for the model are based upon both reported literature values, and experimental values obtained from laboratory grown cultures and pigment standards. Measured and mathematically derived spectra are compared to determine the adequacy of the model, contribute new spectral information, and to establish the proposed spectral interpretation approach as a new detection method for K. brevis. Absorption and scattering properties of K. brevis, such as cell size/shape, internal structure, and chemical composition, are shown to predict the spectral features observed in the measured spectra. This research documents for the first time the exploitation of every spectral feature produced by the interaction of light with the cellular components and their contribution to the total spectrum of a larger (20-40 µm) photosynthetic eukaryote, K. brevis. Overall, this approach could eventually address the detection deficiencies of current optical detection applications and facilitate the understanding of K. brevis bloom ecology.

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