NOAA – As part of an unusual mortality event investigation, a team of scientists has discovered that dead bottlenose dolphins stranded in the northern Gulf of Mexico since the start of the Deepwater Horizon oil spill have lung and adrenal lesions consistent with petroleum product exposure according to a paper published today in the peer-reviewed online journal PLOS ONE. These findings support those of a 2011 health assessment of live dolphins in Barataria Bay, Louisiana, a heavily oiled area during the spill which showed those resident dolphins had poor health, adrenal disease, and lung disease. The timing, location, and nature of the detected lesions support that contaminants from the Deepwater Horizon oil spill caused these lesions and contributed to the high numbers of dolphin deaths within this oil spill’s footprint. Increased dolphin deaths following the oil spill are part of the northern Gulf of Mexico unusual mortality event investigation. Severe bacterial pneumonia in bottlenose dolphin (Tursiops truncatus) that stranded in Barataria Bay, Louisiana in December 2011. (Credit: University of Illinois) “This is the latest in a series of peer-reviewed scientific studies, conducted over the five years since the spill, looking at possible reasons for the historically high number of dolphin deaths that have occurred within the footprint of the Deepwater Horizon spill,” said Dr. Teri Rowles, veterinarian and one of 22 contributing authors on the paper, and head of NOAA’s Marine Mammal Health and Stranding Response Program, which is charged with determining the causes of unusual mortality events, also known as UMEs. “These studies have increasingly pointed to the presence of petroleum hydrocarbons as being the most significant cause of the illnesses and deaths plaguing the Gulf’s dolphin population. This study carries those findings significantly forward.”