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Deepwater Horizon oil spill killed dolphins in record numbers

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  • Deepwater Horizon oil spill killed dolphins in record numbers

    Deepwater spill killed dolphins in record numbers

    By Virginia Morell 20 May 2015 3:30 pm

    One of the biggest mysteries following the Deepwater Horizon oil blowout in April 2010 has been solved. Scientists are now confident the abnormally high numbers of bottlenose dolphins (Tursiops truncatus) that have died—and continue to die—in the oil spill area are suffering from ailments caused by oil byproducts. Although researchers don’t have exact numbers of how many dolphins perished following the spill, they’ve found 1281 stranded and dead between 30 April 2010 and 17 May 2015—the highest number ever recorded in the Gulf of Mexico. Barataria Bay, Louisiana, was particularly hard hit by the spill. Half of the dead dolphins found in this region between June 2010 and November 2012 had a thin adrenal gland cortex—a key indicator of an ailment known as adrenal insufficiency which often leads to death in dolphins, particularly among those who are pregnant. This same lesion was found in one of every three dolphins examined in oil-contaminated areas across Louisiana, Mississippi, and Alabama, the team reports today in PLOS ONE.



    Adrenal Gland and Lung Lesions in Gulf of Mexico Common Bottlenose Dolphins (Tursiops truncatus) Found Dead following the Deepwater Horizon Oil Spill
    • Stephanie Venn-Watson ,
    • Kathleen M. Colegrove,
    • Jenny Litz,
    • Michael Kinsel,
    • Karen Terio,
    • Jeremiah Saliki,
    • Spencer Fire,
    • Ruth Carmichael,
    • Connie Chevis,
    • Wendy Hatchett,
    • Jonathan Pitchford,
    • Mandy Tumlin,
    • Cara Field,
    • [ ... ],
    • Teri Rowles
    • [ view all ]
    • Published: May 20, 2015
    • DOI: 10.1371/journal.pone.0126538


    A northern Gulf of Mexico (GoM) cetacean unusual mortality event (UME) involving primarily bottlenose dolphins (Tursiops truncatus) in Louisiana, Mississippi, and Alabama began in February 2010 and continued into 2014. Overlapping in time and space with this UME was theDeepwater Horizon (DWH) oil spill, which was proposed as a contributing cause of adrenal disease, lung disease, and poor health in live dolphins examined during 2011 in Barataria Bay, Louisiana. To assess potential contributing factors and causes of deaths for stranded UME dolphins from June 2010 through December 2012, lung and adrenal gland tissues were histologically evaluated from 46 fresh dead non-perinatal carcasses that stranded in Louisiana (including 22 from Barataria Bay), Mississippi, and Alabama. UME dolphins were tested for evidence of biotoxicosis, morbillivirus infection, and brucellosis. Results were compared to up to 106 fresh dead stranded dolphins from outside the UME area or prior to the DWH spill. UME dolphins were more likely to have primary bacterial pneumonia (22% compared to 2% in non-UME dolphins, P = .003) and thin adrenal cortices (33% compared to 7% in non-UME dolphins,P = .003). In 70% of UME dolphins with primary bacterial pneumonia, the condition either caused or contributed significantly to death. Brucellosis and morbillivirus infections were detected in 7% and 11% of UME dolphins, respectively, and biotoxin levels were low or below the detection limit, indicating that these were not primary causes of the current UME. The rare, life-threatening, and chronic adrenal gland and lung diseases identified in stranded UME dolphins are consistent with exposure to petroleum compounds as seen in other mammals. Exposure of dolphins to elevated petroleum compounds present in coastal GoM waters during and after the DWH oil spill is proposed as a cause of adrenal and lung disease and as a contributor to increased dolphin deaths.

    Full article:

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