Assessing the Exposures to and Impacts of Oil Constituents and Chemical Dispersants on Marine Invertebrates

Abstract

While the impacts of oil spill events on marine ecosystems have been well studied over the past half-century, continued large scale oil leaks/spills like the Deepwater Horizon Incident serve to highlight how much we still do not fully understand regarding the impacts of oil exposure and the data gaps that exist in current damage assessments and remediation strategies. These events also emphasis how critical it is to have a thorough understanding of the native ecosystem where the oil spills occurs when deciding the best response options during the event, understanding the damages to organisms, and determining what strategies are needed to achieve and assess recovery. Therefore, this dissertation aimed to address observed data gaps in response options, damages assessments, and remediation strategies relevant to the Northern Gulf of Mexico. Firstly, it addresses the lack baseline data necessary to assess exposure to and impacts of oil during and recovery following an oil spill event for offshore pelagic and benthic zones by describing a novel resource for future offshore biomonitoring using oil rig fouling invertebrates. The low baseline accumulation of polycyclic aromatic hydrocarbons (PAHs) and the quick accumulation response following a contamination event observed in this study demonstrates the benefits of using oil rig fouling invertebrates as offshore biomonitoring resources. Secondly, it addresses the lack of data on the acute or sublethal toxicity of oil exposures on an important ecological and economic species in the Gulf of Mexico, the blue crab, Callinectus sapidus. The enclosed studies provide a crucial foundation for understanding the sensitivity of blue crabs at multiple early life stages to oil, chemically-dispersed oil, and chemical dispersants. The blue crab exposure studies highlight the benefit of fully characterizing exposure solutions beyond total petroleum hydrocarbons by using a suit of PAHs and distinguishing between dissolved and particulate fractions of exposure solutions to better understand observed toxicities and potential routes of uptake by organisms. Overall, the data gaps addressed by this research can aid future managers and responders as they decide on response and remediation options following an oil spill in the Northern Gulf of Mexico.