ORCID ID

https://orcid.org/0000-0003-2776-3596

Date Awarded

2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Virginia Institute of Marine Science

Advisor

Michael A Unger

Committee Member

Ryan B Carnegie

Committee Member

Roger L Mann

Committee Member

Jeffrey D Shields

Committee Member

Upal Ghosh

Abstract

Anthropogenic activities such as oil spills are major sources of polycyclic aromatic hydrocarbon (PAH) pollution in the environment. Bivalves such as C. virginica can accumulate high levels of PAHs in tissue due to a limited metabolic capacity for these compounds. Accordingly, bivalves have served as key biomonitoring species for contaminants and exposure to PAH through seafood consumption can also be an important risk to human health due to the toxic and carcinogenic potential of these compounds. For evaluating bivalve PAH levels, conventional analyses are limited due to extensive time and expense and unreliability. This work demonstrates the application of immunological techniques to overcome such limitations in conventional techniques and to explore PAH kinetics and partitioning mechanisms within oysters. Biosensor technology coupled with a PAH antibody was employed to rapidly and inexpensively screen PAH levels in adult oysters in an Elizabeth River watershed monitoring survey. Through a novel extension of a fundamental chemistry theory, PAH concentrations measured in oyster fluid by biosensor were used to predict tissue concentrations. Biosensor-derived predictions had a strong association with tissue concentrations measured by conventional chemical analysis. A strong association between the biosensor and tissue concentrations when compared against regulatory PAH thresholds and efficient mapping of PAH levels throughout the watershed, demonstrates the real-world value of the method. The biosensor was also employed in PAH kinetics studies. Oysters were exposed to crude oil water accommodated fractions (WAF) in the laboratory to explore the application of the biosensor in oil spill response; however, further work is needed to improve the precision of biosensor-derived predictions at non-steady state. In a field exposure study, PAH levels in cultured triploid and diploid oysters deployed at a PAH hotspot in the Elizabeth River were compared to wild oysters inhabiting the site. Differences in PAH kinetic trends were observed between oyster fluid and tissue. When combined with the observed differences in PAH levels in specific tissue types between transplanted and wild oysters, there is evidence that internal partitioning and tissue-specific kinetic rates may be important factors in determining the overall PAH body burden in an oyster and warrants further investigation to improve precision in future biomonitoring efforts. The fluorescently tagged PAH antibody was also employed in an immunohistochemical (IHC) technique to visualize complex PAH mixtures within oyster tissue. Oysters were collected throughout the laboratory WAF exposure, and the observed change in signal intensity in tissue followed a similar trend to measured PAH concentrations. In visualizing transplanted vs. wild oyster tissue, the trends in signal intensity supported the differences observed in tissue-specific PAH concentrations between groups. Overall, the biosensor shows promise as a tool to overcome current analytical challenges faced in environmental monitoring of biota. While further work is needed to understand the influence of chemical and biological factors on PAH kinetics and biosensor-derived tissue predictions, the unique analytical features of these technologies are valuable for addressing these mechanistic questions. When coupled with IHC, these immunologic techniques can provide new insight to address complexities in environmental pollution and health risk assessments that cannot be as feasibly and inexpensively answered by standard methods.

DOI

https://dx.doi.org/10.25773/v5-kx83-h138

Rights

© The Author

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