Degree

Master of Science (MS)

Department

Environmental Resource Science

Document Type

Thesis

Abstract

Characterizing phytoplankton diversity is critical for large-scale biodiversity monitoring and harmful algal bloom (HAB) detection. Here, we present a micro hyperspectral imaging method to characterize reflectance signatures, for the first time across major phytoplankton groups. Spectral variability among taxa in laboratory cultures is interpreted using algal pigment and absorption analyses, demonstrating that pigment composition and absorption govern reflectance features. Chlorophytes and cryptophytes exhibit distinct spectral signatures and are readily distinguishable, whereas diatoms and dinoflagellates show greater spectral similarity, with differentiation relying on subtle reflectance features associated with chlorophyll c₁c₂ near ~463 nm and within 620–650 nm. We further applied this method to field samples from Lac des Allemands to expand the spectral library and link endmember spectra with field-collected remote sensing reflectance (Rrs) for algal assemblage unmixing. As a proof of concept, the unmixing framework was evaluated using wavelength configurations approximating NASA’s new hyperspectral missions, PACE, and EMIT (2.5 and 7 nm resolution). Cyanobacterial dominance (~60-80%) over diatoms and chlorophytes was consistently identified at both PACE and EMIT spectral settings, in agreement with pigment indicators (e.g., zeaxanthin). Furthermore, genus-level detection identified Dolichospermum sp. and Oscillatoria sp. as dominant taxa, in agreement with microscopy. The reconstructed spectra exhibited high similarity (SAM: 1.63°–2.95°), highlighting the potential of integrating micro-hyperspectral imaging with spectral unmixing to enhance phytoplankton discrimination from hyperspectral satellite observations, thereby advancing HAB monitoring at high spatiotemporal and community level resolution across broad spatial scales. The resulting algal endmember library provides a valuable resource for the ocean color community.

Date

2-6-2026

DOI

https://proquest.com/docview/3347951615

First Committee Chair

Jorge Villa

Second Committee Chair

Bingqing Liu

First Committee Member

Beth Stauffer

Second Committee Member

Brian Schubert

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