HCNSO Student Theses and Dissertations

Defense Date

4-2015

Document Type

Thesis

Degree Name

M.S. Marine Biology

Department

Oceanographic Center

First Advisor

David W. Kerstetter

Second Advisor

Erin J. Burge

Third Advisor

Richard Spieler

Abstract

Following the BP Deepwater Horizon oil spill event, there was a critical need to assess the effects of the oil and dispersant chemicals on the coastal pelagic fish complex in the Gulf of Mexico and the Florida Straits. The objective of this study was to determine if spilled crude oil and dispersant chemicals have posed an ecological risk to the coastal pelagic fish complex through the detection of vitellogenesis. Crude oil containing polycyclic aromatic hydrocarbons (PAHs), dispersant chemicals and other estrogen-mimicking compounds are suspected to induce vitellogenin production in male and immature female fish, normally only produced by sexually mature females. Blood plasma and surface mucus were collected from wild-caught adult and juvenile males and females from as many representative coastal pelagic species as possible (including yellowfin tuna Thunnus albacares and swordfish Xiphias gladius). To create a control for this experiment, crevalle jacks (Caranx hippos) and lookdowns (Selene vomer) were injected with estradiol-17β (10 μg/g body weight) into the peritoneal cavity to induce vitellogenesis, regardless of sex or reproductive stage. The mucus and blood plasma of each injected fish was collected 7 to 11 days post-injection. Mucus and blood plasma samples of wild-caught and experimentally-injected fishes were separated using sodium dodecyl sulphate-polyacrylamide gel electrophoresis, stained with a phosphoprotein specific fluorescent dye (Pro-Q Diamond®), and visualized through ultraviolet transillumination. Vitellogenin was visibly detectable in the mucus collected from the control-injected fish, suggesting a disruption in the endocrine system as a result of estrogen exposure (estradiol-17β). However, there were no elevated levels of vitellogenin detected in any wild-caught fish mucus or blood plasma samples, indicating no vitellogenesis. From this, we infer that there has been no detectable endocrine disruption to the sampled coastal pelagic fish complex in the Gulf of Mexico two years after the start of the spill.

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