Deepwater Horizon Spill Increased Dolphin Deaths, Study Shows

  • Research & Development

After commemorating the 5-year anniversary of the BP Deepwater Horizon oil disaster, another study has been released highlighting the significant injury to bottlenose dolphins in the Gulf of Mexico.

The National Oceanic and Atmospheric Administration (NOAA) published new results pointing to dolphin injury from the oil disaster. Since 2010, there has been an unusually high number of dolphin deaths in the northern Gulf, the most severe dolphin die-off ever recorded in the region. Scientists have conducted autopsies on dead dolphins to try and understand why they are dying.

As NOAA reported, Barataria Bay, Louisiana, was one of the most heavily oiled coastal areas from the Deepwater Horizon oil spill, and the new study shows that half of the dead dolphins examined from Barataria Bay that stranded between June 2010 and November 2012 had a thin adrenal gland cortex, indicative of adrenal insufficiency.

One in every three dolphins examined across Louisiana, Mississippi and Alabama had this lesion. In comparison, only 7 percent of the dead stranded reference dolphins, collected from other coastal regions outside the Deepwater Horizon oil spill area and time frame, had a thin adrenal cortex.

In fact, almost half of the dolphins with this otherwise rare adrenal lesion appeared to have died without another clear explanation for their death.

In addition to the adrenal lesions, the scientific team discovered that more than one in five dolphins that died within the Deepwater Horizon oil spill footprint had a primary bacterial pneumonia. Many of these cases were unusual in severity, and caused or contributed to death.

As a result, NOAA concluded: “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.”

Kara Lankford, Associate Director of Ocean Conservancy’s Gulf Restoration Program stated: “The new study released by NOAA should remind us that the BP oil disaster will have a continued impact on the Gulf of Mexico and the species who call it home. The question remains to what extent? We must remain vigilant and monitor the Gulf ecosystem in order to guide restoration where it is most needed and be able to track recovery. These new findings should be a resounding reminder to our Gulf leaders that restoration dollars should be spent on restoring the invaluable natural resources of the Gulf of Mexico.”

The study  was completed as a part of the Northern Gulf of Mexico unusual mortality event investigation and a part of the Deepwater Horizon Natural Resource Damage Assessment being conducted cooperatively among NOAA, other federal and state trustees, and BP.

Image: NOAA

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