Abstract

A wide variety of contaminants are released into coastal marine environments from human activities, including manufacturing, pesticides, mining, smelting, waste incineration, and burning of fossil fuels in addition to their uses in plastics, detergents, paints, and antibacterial soaps.¹ These anthropogenic contaminants in the marine environment biodegrade slowly, bioaccumulate in organisms, and can cause reproductive, immune, and developmental effects on wildlife; however, the effects of some of these contaminants have not been extensively studied in cetaceans.^2,3,4 This study helps expand the knowledge base concerning quantities and biological effects of anthropogenic contaminants in stranded cetaceans in the southeastern United States sampled during 2012–2017. Concentrations of inorganic chemicals and a number of additional endocrine disrupting contaminants in blubber and liver samples of stranded cetaceans were measured, and gross and microscopic pathology data were retrospectively evaluated to identify demographic and/or pathologic data that may be linked to those contaminants. We analyzed 67 cases of stranded cetaceans, including mostly odontocetes (Tursiops truncatus [N=33]; Kogia breviceps [N=17]; Stenella frontalis [N=4]; Mesoplodon europaeus [N=3]; Stenella attenuata [N=2]; Kogia sima [N=2]; Peponocephala electra [N=2]; Globicephala macrorhynchus [N=1]; Lagenorhynchus albirostris [N=1]; Grampus griseus [N=1]); and one mysticete (Megaptera novaeangliae). Liver samples were evaluated for 19 inorganic chemicals (Al, As, Ba, Be, Cd, Cs, Co, Cu, Fe, Pb, Li, Mg, Mn, Hg, Mb, Ni, Se, Tl, Zn) using inductively coupled plasma-mass spectrometry. Blubber samples were analyzed for five known endocrine disrupters (atrazine, bisphenol A [BPA], diethylphthalates, nonylphenol ethoxylates, triclosan) using gas chromatography-mass spectrometry. Complete reviews of demographic, pathologic, and toxicologic reports for each individual animal were performed, and compiled data were analyzed using basic statistics and multivariate logistic regression. Histopathologic findings in the endocrine and reproductive systems included: multifocal nodular thyroid hyperplasia; bilateral adrenal pheochromocytomas; benign seminoma with tumor necrosis and fibrosis; and pituitary periadenitis, which correlated to relatively higher concentrations of diethyl phthalates, BPA, and triclosan. Histopathologic findings in the hepatobiliary system included multifocal centrilobular hepatocellular necrosis; biliary hyperplasia; and nodular extramedullary hematopoiesis, that were positively correlated to elevated concentrations of Fe and Hg. Initial correlation analyses revealed positive correlations (≥0.7) between concentrations of mercury and selenium; mercury and cadmium; and selenium and cadmium. For individual species, mean concentrations of iron and magnesium in K. breviceps and T. truncatus; mean concentration of nonylphenol ethoxylates in K. breviceps; and mean concentration of BPA in T. truncatus were elevated compared to other species. In general, the mean concentration of BPA in blubber samples (29.70 ppm ±90.97) exceeded all other endocrine disrupting contaminants tested. The results of this study provide information on possible lesions associated with chronic exposure to a subset of contaminants, which have not been thoroughly characterized to date. This study highlights that anthropogenic impacts coincide with health implications to wildlife populations and environmental stability, and provides meaningful information for investigators of marine ecosystem health.

Acknowledgements

The authors thank our regional marine mammal stranding network partners for providing cetacean necropsy data and tissue samples for this study, including the FAU Harbor Branch Stranding, Health, and Rehabilitation Program, and the Marine Mammal Stranding Network of the North Carolina Central Coast. We also acknowledge Michigan State University’s Veterinary Diagnostic Laboratory and the University of Georgia Center for Applied Isotope Studies for sample analysis and data interpretation. We thank the Harbor Branch Oceanographic Institute Foundation and the Florida Atlantic University Kelly Family Foundation Scholarship Program for providing financial support for this project.

* Presenting author
+ Student presenter

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