Year

2025

Season

Fall

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

Committee Chairperson

Dr. Jim Gelsleichter

Second Advisor

Dr. Nikki Dix

Third Advisor

Dr. Eric Johnson

Department Chair

Dr. Jim Gelsleichter

Abstract

The Guana and Tolomato Rivers provide essential habitat for several ecologically and economically important species and is a well-loved and recreated area. Spanning the northeastern Florida coast, the rivers are home to over 50 endangered or threatened species and host several habitat restoration projects due to their ecological significance and proximity to development along the coast. The effects of human influence and pollution, and specifically toxic metal mercury (Hg) and perfluoroalkyl substances (PFAS), are not well known within the system. Hg is known to biomagnify within food webs, and there is a considerable lack of literature concerning PFAS behavior within the environment, much less food webs. Therefore, this thesis aimed to answer the uncertainty regarding Hg and PFAS within organisms of the Guana and Tolomato Rivers, as well as aimed to identify significant trends across species, feeding guilds, and sampling regions to greater elucidate patterns of movement throughout the food web and ecosystem at large. Muscle biopsies and blood plasma sampled from shellfish, finfish, and elasmobranchs in the Guana and Tolomato Rivers were analyzed for their Hg and PFAS content respectively, and the results were statistically analyzed for trends. Overall, low levels of both Hg and PFAS were observed. 82% of Hg samples fell below the EPA’s safe consumption threshold of 0.3 mg/kg w.w., and PFAS burdens found in this system are drastically lower than values reported in coastal waters across the United States. Hg was found to biomagnify up the food web, whereas PFAS diluted up the trophic levels. There was no significant relationship between sampling region, despite vastly different industrial influences between the catch sites. This thesis supports a positive outlook on the health of the system and provides novel information regarding PFAS in estuarine systems.

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