Gulf of Mexico dolphin deaths likely due to oil exposureStudy finds higher rate of illness and death in newborns and juvenile bottlenose dolphins after Deepwater Horizon oil spill.
The increased number of stranded stillborn and juvenile dolphins found in the Gulf of Mexico from 2010 to 2013 were likely caused by chronic illnesses in mothers who were exposed to oil from the Deepwater Horizon spill, scientists said in a NOAA statement today (April 12, 2016). The new study, published in the journal Diseases of Aquatic Organisms, is part of an effort to explain the unusual mortality event in the Gulf involving bottlenose dolphins between early 2010 and continuing into 2014. Veterinarian Teri Rowles, co-author on the study, is head of NOAA’s Marine Mammal Health and Stranding Response Program, which is charged with determining the causes of these events. Rowles said:
Dr. Kathleen Colegrove, Ph.D., is the study’s lead author and veterinary pathology professor at the University of Illinois Chicago-based Zoological Pathology Program. She said:
Scientists saw higher numbers of stranded stillborn and juvenile dolphins in the spill zone in 2011 than in other years, particularly in Mississippi and Alabama. Dr. Stephanie Venn-Watson is a study co-author and veterinary epidemiologist from the National Marine Mammal Foundation. She said:
Bottlenose dolphins are pregnant for about 380 days, so stillborn and juvenile dolphins found in the early months of 2011 could have been exposed in the womb to petroleum products released the previous year. “Pregnant dolphins losing fetuses in 2011 would have been in the earlier stages of pregnancy in 2010 during the oil spill,” said Colegrove. The researchers report that 88 percent of the stillborn and juvenile dolphins found in the spill zone had abnormal lung, including partially or completely collapsed lungs. That and their small size suggest that they died in the womb or very soon after birth – before their lungs had a chance to fully inflate. Only 15 percent of stillborn and juvenile dolphins found in areas unaffected by the spill had this lung abnormality, the researchers said. The investigations into both the fetal dolphin, and the overall the effects of the oil spill, are continuing. The long-term effects of the spill on dolphin reproduction are still unknown. Bottom line: A new study published in the journal Diseases of Aquatic Organisms suggests that the increased number of stranded stillborn and juvenile dolphins found in the Gulf of Mexico from 2010 to 2013 were caused by chronic illnesses in mothers who were exposed to oil from the Deepwater Horizon spill. Enjoying EarthSky? Sign up for our free daily newsletter today!
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