Graduation Year

2020

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Marine Science

Major Professor

Steven A. Murawski, Ph.D.

Committee Member

Erin L. Pulster, Ph.D.

Committee Member

Ernst Peebles, Ph.D.

Keywords

Fish, Oil, PAH, Contaminants

Abstract

Fisheries populations and their ecosystems are negatively impacted by both chronic and acute inputs of pollutants, including oil spills such as the Deepwater Horizon platform blowout in 2010 in the Gulf of Mexico (GoM). After Deepwater Horizon, toxicological studies of demersal fishes of the northern GoM were undertaken to characterize impacts and to establish baseline contaminant levels in the aftermath of the spill. In this study, I quantify polycyclic aromatic hydrocarbon (PAH) concentrations in eight pelagic fish species to demonstrate oil exposure differences between species, region and time. Analysis of biliary PAH metabolite equivalents using high performance liquid chromatography was used to estimate short-term and acute exposure in pelagic fishes (n = 102). Hepatic PAH concentrations of 19 parental PAHs and their alkylated homologs in pelagic liver samples (n = 142) were quantified using QuEChERS extractions and GC/MS/MS to quantify long-term and chronic exposure. The hepatic ∑46PAH (sum of 46 parental and homolog PAH compounds) concentration ranges quantified for all species and regions (21.2 to 468 ng g-1 wet weight) are within the range found previously in the GoM region for demersal and reef fishes. Biliary PAH equivalent ∑3FAC concentrations (fluorescent aromatic compounds of three PAH indicators) ranged from 4,400 to 1,400,000 ng FAC g-1 bile, which were also within the same range as demersal and reef species in this region. However, mean biliary PAH concentrations measured in Yellowfin Tuna (855 µg FAC g-1) from the north central GoM were more than three times higher than Golden Tilefish (263 µg FAC g-1) and 20 times higher than Yellowedge Grouper (Hyporthodus flavolimbatus, 41 µg FAC g-1) collected in the same region. Significant negative relationships between PAH concentrations, biometrics (e.g. fish length), and putative indices of fish health including Fulton’s condition factor and the hepatosomatic index were identified for multiple species. Intraspecies and regional differences were also identified for Greater Amberjack, Seriola dumerili, and Yellowfin Tuna, Thunnus albacares, suggesting variation in PAH sources across region. Produced waters from oil and gas platform discharges among other sources including riverine input, atmospheric deposition, burning of fossil fuels, resuspension of contaminated sediments, and chronically leaking wells are likely contributing to regional differences within species. Furthermore, the high levels of PAH exposure in pelagic species compared to demersal and reef species, indicated by biliary fluorescent aromatic compounds (FACs), warrants further investigation to identify the prominent source of surface water PAHs and the specific physiological species differences that govern the observed high rates of exposure and metabolic clearance for species such as the Yellowfin Tuna.

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