Electronic Thesis and Dissertation Repository


Master of Science




Dr. Charles G. Trick


Harmful algal blooms (HABs) are vast expanses of noxious or toxic phytoplankton that periodically dominate coastal ocean waters or freshwater systems. An especially damaging type of HAB are the species that kill fish. In this thesis, a potentially invasive marine fish-killing flagellate, Prymnesium parvum, was investigated for its tolerance to freshwater conditions. This species has invaded some freshwater systems in the southern United States. The thesis examines if the growth rate and toxicity of Prymnesium parvum remain high under low salinities similar to freshwater systems. A hemolytic lysis assay was used as a proxy for toxicity. The findings presented here indicate that the three Prymnesium parvum isolates shared a similar growth and toxicity response, regardless of origin. All isolates could grow well at low salinities and all retain their toxicity. Findings from this thesis indicate that should this species “invade” and establish itself in the Great Lakes, it could thrive and exhibit a toxic phenotype.