Graduation Year

2023

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Biology (Integrative Biology)

Major Professor

Heather Judkins, Ph.D.

Committee Member

Isabel Romero, Ph.D.

Committee Member

Melanie Riedinger-Whitmore, Ph.D.

Keywords

Bioaccumulation, fluorescence, Nile red, phthalates, watershed

Abstract

Microplastic pollution is an increasingly alarming concern with widespread global distribution in aquatic environments. Filter feeding organisms such as bivalves, have a heightened risk of microplastic ingestion through free floating particulates in the water. This can lead to bioaccumulation moving up through trophic levels to apex predators and humans. Spatial and temporal differences in microplastic abundance were evaluated in the Eastern Oyster, Crassostrea virginica, at six sites within Tampa Bay. Oyster tissue was digested using 30% hydrogen peroxide (H2O2) and microplastics were quantified using Nile Red dye and fluorescent particle excitement. A total of 3025 microplastics were found throughout six study sites over two seasons (winter 2021 and summer 2022) with varying site types and regionality. Microfragments (n = 2867) made up the majority of findings compared to microfibers (n = 158). Significant differences were observed among the sites studied, site type, and their location in the bay. Outflow and marina areas had significantly higher (p < 0.01) amounts of microplastic compared to preserve areas, and the east bay had significantly higher (p < 0.05) amounts than the west bay. Microplastic accumulation in bivalves can be associated with spatial differences and site type. Findings suggest microplastic contamination is associated with higher urbanization, proximity to drainage basins, and recreation.

Phthalate esters (PAEs), Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorinated pesticides (OCPs), ultraviolet filters, and fecal sterols were measured in 30 C. virginica samples collected through Tampa Bay, Florida to better understand trends in aquatic contamination and chemical leaching from microplastic ingestion. These samples came from a preserve area (Riviera Bay), marina (Bayboro Harbor), and outflow area (Big Bend Channel). Samples had varying levels of microplastic ingestion. Mantle tissue was freeze dried and went through solvent extraction before going through gas chromatography with tandem mass spectrometry (GC/MS/MS). PAHs, PCBs, OCPs, UV filters, and fecal sterols were used to determine PAE vector sources. PAEs were analytes of concern as they have the potential to be released from plastic degradation. Results show there is no significance regarding microplastic ingestion and chemical contamination. The only significant trend between sites organic compound groups showed higher PAHs (p < 0.05) at Bayboro Harbor. Three of the six phthalate analytes were spatially significant (p < 0.05) with dimethyl phthalate DMP having the highest concentrations of all analytes. Phthalate concentrations were strongly correlated with OCPs and UV filters indicating that phthalate contamination stems primarily from direct anthropogenic impact to bivalves in Tampa Bay.

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