Cardiac assessments of bottlenose dolphins (Tursiops truncatus) in the Northern Gulf of Mexico following exposure to Deepwater Horizon oil

• Published in: PloS one Vol. 16; no. 12; p. e0261112
• Main Authors: Linnehan, Barbara K, Gomez, Forrest M, Huston, Sharon M, Hsu, Adonia, Takeshita, Ryan, Colegrove, Kathleen M, Harms, Craig A, Barratclough, Ashley, Deming, Alissa C, Rowles, Teri K, Musser, Whitney B, Zolman, Eric S, Wells, Randall S, Jensen, Eric D, Schwacke, Lori H, Smith, Cynthia R
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 14.12.2021; Public Library of Science (PLoS)
• Subjects: Abnormalities; Animals; Aorta; Aortic valve; Aquatic mammals; Armed forces; Auscultation; Beaked whales; Biology and Life Sciences; Blood flow; Bottle-Nosed Dolphin - abnormalities; Bottle-Nosed Dolphin - physiology; Cardiac function; Cardiology; Cetacea; Coronary artery disease; Crude oil; Diastole; Dolphins; Dolphins & porpoises; Doppler effect; Earth Sciences; Echocardiography; Echocardiography - veterinary; Ecology and Environmental Sciences; EKG; Electrocardiogram; Electrocardiography; Electrocardiography - veterinary; Environmental aspects; Environmental cleanup; Evaluation; Exposure; Fibrosis; Fibrosis - diagnostic imaging; Fibrosis - veterinary; Flow velocity; Health aspects; Heart - diagnostic imaging; Heart - physiology; Heart attacks; Heart diseases; Heart Injuries - diagnostic imaging; Heart Injuries - veterinary; Heart valves; Histopathology; Hydrocarbons; Hypertension; Hypertension - veterinary; Information warfare; Laboratory animals; Lung diseases; Marine mammals; Medicine and Health Sciences; Oil spills; Petroleum Pollution - adverse effects; Physiological aspects; Research and Analysis Methods; Septum; Sinuses; Stranding; Thickening; Tricuspid valve; Tursiops truncatus; Ultrasonic imaging; Ventricle; Wall thickness; Water consumption; United States; North Carolina; Sarasota Florida; Gulf of Mexico; California; United States > US; Dauphin Island
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0261112

The Deepwater Horizon (DWH) oil spill profoundly impacted the health of bottlenose dolphins (Tursiops truncatus) in Barataria Bay, LA (BB). To comprehensively assess the cardiac health of dolphins living within the DWH oil spill footprint, techniques for in-water cardiac evaluation were refined with dolphins cared for by the U.S. Navy Marine Mammal Program in 2018 and applied to free-ranging bottlenose dolphins in BB (n = 34) and Sarasota Bay, Florida (SB) (n = 19), a non-oiled reference population. Cardiac auscultation detected systolic murmurs in the majority of dolphins from both sites (88% BB, 89% SB) and echocardiography showed most of the murmurs were innocent flow murmurs attributed to elevated blood flow velocity [1]. Telemetric six-lead electrocardiography detected arrhythmias in BB dolphins (43%) and SB dolphins (31%), all of which were considered low to moderate risk for adverse cardiac events. Echocardiography showed BB dolphins had thinner left ventricular walls, with significant differences in intraventricular septum thickness at the end of diastole (p = 0.002), and left ventricular posterior wall thickness at the end of diastole (p = 0.033). BB dolphins also had smaller left atrial size (p = 0.004), higher prevalence of tricuspid valve prolapse (p = 0.003), higher prevalence of tricuspid valve thickening (p = 0.033), and higher prevalence of aortic valve thickening (p = 0.008). Two dolphins in BB were diagnosed with pulmonary arterial hypertension based on Doppler echocardiography-derived estimates and supporting echocardiographic findings. Histopathology of dolphins who stranded within the DWH oil spill footprint showed a significantly higher prevalence of myocardial fibrosis (p = 0.003), regardless of age, compared to dolphins outside the oil spill footprint. In conclusion, there were substantial cardiac abnormalities identified in BB dolphins which may be related to DWH oil exposure, however, future work is needed to rule out other hypotheses and further elucidate the connection between oil exposure, pulmonary disease, and the observed cardiac abnormalities.