Impacts of Oil Exposure During Early Life Development Stages In Sheepshead Minnows (Cyprinodon variegatus) Under Different Environmental Factors
The release of approximately 5 million barrels of crude oil into the northern Gulf of Mexico during the 2010 Deepwater Horizon oil spill jeopardized estuarine ecosystem health from Texas to Florida. These estuarine habitats, which serve as nurseries for many important fisheries are also prone to rapid fluctuations in environmental stressors such as oxygen concentration, and salinity. The consequence of combined exposure to crude oil and suboptimal environmental factors during early life stage development of fish is still largely unknown. The objective of this project was to investigate the impacts of exposure to crude oil in combination with varying environmental stressors on Cyprinodon variegatus survival, gene expression, and genotoxicity. The post-larval developmental stage was the most sensitive early life stage to oil and abiotic stress. Median lethal concentrations during the post-larval exposures followed a treatment dependent pattern with the greatest lethal effect seen under hypoxic-high salinity conditions (64.55 µg/L ± 12.81). Real-time PCR analysis identified down-regulation of cyp1a1, epo, and arnt1, target genes involved in the two common defense pathways, the aryl hydrocarbon receptor signaling pathway which modulates metabolism of polycyclic aromatic hydrocarbons (PAHs), and the hypoxia inducible 1-α signaling pathway which is responsible for resilience to hypoxic stress, this was only observed under hypoxic-high salinity environmental conditions in treatments with PAH concentrations greater than 226 µg/L. Top toxicological functions impacted during post-larval development in all treatment comparisons included cholesterol biosynthesis, cardiotoxicity, and hepatoxicity. These findings indicate that the post-larval stage is the most sensitive to oil and environmental stress.
Deepwater Horizon, sheepshead minnows, hypoxia, oil, development, gene expression, and RNA sequencing, Pharmacology, Toxicology and Environmental Health
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