Date of Award
5-2023
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Biological Sciences
Committee Chair/Advisor
William S. Baldwin
Committee Member
Peter van den Hurk
Committee Member
Charles D. Rice
Abstract
Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant that is known for its surfactant properties and its resistance to degradation. The persistence and lipophilicity of PFOS in surface waters have led to its bioaccumulation in fish, which in turn leads to its accumulation and toxic effects in humans that consume fish. PFOS is also hypothesized to perturb reproduction and survival of low and mid-trophic level zooplankton species such as Daphnia magna that are food for multiple fish species. In this study, a 21-day D. magna chronic toxicity test was performed using 1,10, 100, 1000, and 5000 ppb of PFOS to determine the concentration of PFOS in the whole body and its effects on fecundity, survival, and estimated population growth. PFOS showed concentration dependent decreases in survival and fecundity in D. magna and reduced reproductive success at concentrations above 10 ppb of PFOS. Salinity is a physiochemical property of water that can potentially enhance PFOS accumulation due to the presence of ions such as Ca+ and Mg2+ in the water; however, the difference in PFOS bioconcentration between freshwater and saltwater fish is not well studied. Estuarine fish species Fundulus heteroclitus (mummichog) is known for its adaptation to both hypertonic and hypotonic environments, which makes it an ideal organismal model to determine differences in the bioconcentration of PFOS in saltwater compared to freshwater in the same species. F. heteroclitus were adapted to both saltwater (23-26 ppt) and freshwater (moderately hard water; 0.143 ppt) conditions for 30 days before being treated with PFOS for 20 days to determine if bioconcentration of PFOS is higher in the liver, gills, and muscle of saltwater mummichogs compared to freshwater-acclimated mummichogs. At 100 ppb, PFOS bioconcentrations were higher in saltwater versus freshwater in the liver and muscle of F. heteroclitus. At 1 ppb PFOS and below, some of these effects were reserved but rarely statistically significant. The physiological adaptability of F. heteroclitus in different environments is facilitated by changes in expression of ionic and xenobiotic transporters within the gills. The glucocorticoid receptor (GR) showed significant decreases in mRNA expression when exposed to PFOS in saltwater mummichogs which can lead to disruption in downstream signaling of the cystic fibrosis transmembrane receptor (CFTR). Bioconcentration factors for F. heteroclitus and D. magna were determined and concentrations in the liver and gills of both saltwater and freshwater-acclimated mummichogs were compared to D. magna. In general, PFOS accumulation was greater in F. heteroclitus than in D. magna in the liver but was greater in D. magna in the muscle. In conclusion, PFOS accumulation is exacerbated by salinity at high concentrations in the tissues of F. heteroclitus and PFOS hinders reproductive success in D. magna.
Recommended Citation
Davis, Tyler, "Role of Salinity in Perfluorooctane Sulfonate (PFOS) Bioconcentration between Aquatic Species and the Differential Regulation of Transporters in Fundulus Heteroclitus" (2023). All Theses. 4076.
https://tigerprints.clemson.edu/all_theses/4076