Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8385
Title: Corresponding morphological and molecular indicators of crude oil toxicity to the developing hearts of mahi mahi
Author: R. C. Edmunds, Anthony Gill, D. H. Baldwin, T. L. Linbo, B. L. French, Tanya L. Brown, Andrew Esbaugh, Edward Mager, John Stieglitz, Ronald Hoenig, Daniel Benetti, Martin Grosell, N. L. Scholz, J. P. Incardona
Publication Year: 2015
Journal: Scientific Reports
Keywords: Deepwater Horizon,Oil spills,fish development,cardiovascular,gene expression,biomarkers

            Background. Crude oils from distinct geological sources worldwide are toxic to the developing hearts of fish. When oil spills occur in fish spawning habitats, natural resource injury assessments often rely on conventional morphometric analyses of heart form and function in embryos and larvae. The extent to which these visible indicators correspond to more subtle molecular markers for cardiovascular stress is not known. A mechanistic understanding of the crude oil cardiotoxicity syndrome at the molecular level could greatly improve the resolving power and throughput of future impact assessments. Here we exposed the embryos of mahi mahi (Coryphaena hippurus), a top pelagic predator from the Gulf of Mexico, to field-collected crude oil samples from the 2010 Deepwater Horizon disaster. We compared visible heart defects (edema, abnormal looping, reduced contractility) to changes in the expression of cardiac-specific genes that are diagnostic of heart failure in humans, or are associated with loss-of-function cardiac mutants in zebrafish.

            Results. As anticipated, mahi mahi exposed to crude oil during embryogenesis displayed the typical symptoms of the cardiogenic syndrome as larvae, albeit with a relatively mild phenotype. Contractility, looping, and circulatory defects were evident, but larval mahi mahi did not exhibit the craniofacial and body axis abnormalities that are downstream of severe heart failure in other wild fish species examined to date. A gradation of oil exposures yielded concentration-responsive changes in the expression patterns of several cardiac-specific genes. The relative sensitivity of the two categories of markers was influenced by age, with morphological and molecular indicators showing more responsiveness during early and later larval development, respectively..

            Conclusion. We have adapted diagnostic tools developed in part for heart disease screening in humans to refine our understanding of the crude oil cardiotoxicity syndrome in a wild fish species potentially impacted by the 2010 Deepwater Horizon spill. Our findings suggest that 1) morphometric analyses of cardiac function are more sensitive to the proximal and partially reversible effects of crude oil-derived chemicals on the heart, and 2) molecular indicators reveal a longer-term adverse shift in the trajectory of heart formation and developmental modification.

Theme: Habitats to Support Sustainable Fisheries and Recovered Populations
Foci: Assess the impacts of toxic chemicals and other pollutants across biological scales, and identify pollution reduction strategies that improve habitat quality.
Official Citation:

Edmunds, R.C., Gill, A., Baldwin, D.H., Esbaugh, A.J., Mager, E.M., Hoenig, R., Stieglitz, J.D., Benetti, D.D., Grosell, M., Scholz, N.L., and Incardona, J.P. 2015. Corresponding morphological and molecular indicators of crude oil toxicity to the developing hearts of mahi mahi. Scientific Reports, 5:17326.