Date on Honors Thesis

5-2026

Major

Environmental Science

Minor

Wildlife & Conservation Biology; Spanish

Examining Committee Member

Jane Benson, MS, Advisor

Examining Committee Member

Emily Johnson, MS, Committee Member

Examining Committee Member

Michael Flinn, PhD, Committee Member

Abstract/Description

Red tide, caused by the dinoflagellate Karenia brevis, is an algal bloom event that occurs annually in the West Florida Continental Shelf. The algae releases brevetoxin, a toxin that can be fatal to wildlife in high concentrations. These algal bloom events are thought to be exacerbated by warming ocean temperatures and increased nutrient runoff from urbanization. Red tide is responsible for the mass mortality of various marine organisms like the Florida manatee (Trichechus manatus latirostris). This study analyzes the changes in nutrient runoff and sea surface temperatures, and how these factors affected red tide cell concentrations and Florida manatee mortalities on the West Florida Continental Shelf. Four years (2003, 2013, 2018, and 2021), each with 100 or more red tide-related Florida manatee mortalities, were analyzed using GIS mapping and analysis. It is hypothesized that years with more urban land cover and warmer sea surface temperatures will have had higher concentrations of K. brevis and therefore had more red tide-related Florida manatee deaths in the West Florida Continental Shelf. According to the results of this study, the percentage of samples that had high concentrations of K. brevis coincided with total nutrient load in the four study years. The other variables, including manatee mortalities, sea surface temperature, annual rainfall, and impervious surface fraction did not explicitly increase and decrease with the percentage of samples that had high concentrations of K. brevis in the study years. The potential solutions to mitigate harmful algal blooms, including red tide, include public education, legislation, and minimizing fertilizer use.

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