Publication Date

2014-11-25

Availability

Embargoed

Embargo Period

2016-11-24

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Marine Biology and Fisheries (Marine)

Date of Defense

2014-09-25

First Committee Member

Martin Grosell

Second Committee Member

Daniel D. Benetti

Third Committee Member

M. Danielle McDonald

Fourth Committee Member

Robert K. Cowen

Fifth Committee Member

Gavin Partridge

Abstract

The Deepwater Horizon oil spill of 2010 is the largest unintended marine oil spill in history. The point-source location of the spill, below the pelagic zone of the northern Gulf of Mexico (GOM), resulted in distribution of crude oil throughout the water column in the open ocean pelagic environment as well as along near-shore coastal habitats. Additionally, unprecedented use of chemical dispersants at both the surface and at depth resulted in increased dissolution of the crude oil into the aqueous phase. Given the importance of regional finfish and shellfish fisheries in the GOM, much attention has been directed to quantifying the damage to these natural resources. Polycyclic aromatic hydrocarbons (PAHs) comprise some of the most toxic chemicals within crude oil. While a considerable amount of information exists on the effects of PAHs on aquatic invertebrate and vertebrate species, especially those in areas of previous oil spills such as Alaska following the Exxon Valdez oil spill, little is known regarding the effects of such toxins on tropical pelagic species. Pelagic fish species such as mahi-mahi (Coryphaena hippurus), tuna (Thunnus spp.), and cobia (Rachycentron canadum) can present unique challenges in captivity and laboratory settings, which has limited their inclusion in previous assessments of damage from marine oil spills. Results from this dissertation provide novel techniques and technology to successfully maintain and volitionally spawn cobia and mahi-mahi throughout the year, allowing for toxicity testing to be conducted on such species on a continuous basis. Additionally, development of an innovative bioassay system for quantifying the effects of DWH crude oil on the early life-stages (ELSs) of these species allowed for testing of whether UV-radiation results in increased toxicity of DWH crude oil on mahi-mahi ELSs. Given the finding that photo-induced toxicity of DWH crude oil is over nine times that of the same crude oil under limited UV-radiation exposure, it is likely that many of the laboratory (i.e. limited UV-radiation) experiments quantifying toxicity of the spilled oil represent conservative estimates. In the same respect that UV-radiation is often left out of acute toxicity quantification efforts, the sub-lethal effects of crude oil exposure on adult life stage animals are also difficult to quantify and therefore poorly represented in damage assessment efforts. This dissertation provides evidence of DWH crude oil induced sub-lethal impacts to the swimming capacity and efficiency of young adult mahi-mahi at environmentally-relevant exposure levels. Overall, this dissertation provides novel insights into the effects of the DWH oil spill on economically and ecologically valuable pelagic fish species allowing for accurate quantification of the damages incurred by these important natural resources.

Keywords

Deepwater Horizon; mahi-mahi; pelagic; oil; fish; Gulf of Mexico

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