Deepwater Horizon Oil Spill Still Impacts Bottlenose Dolphins Near Gulf Coast

First Posted: Dec 20, 2013 03:59 PM EST
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The Deepwater Horizon spill caused billions of dollars-worth of damage. It impacted fisheries and beaches throughout the Gulf Coast. Now, though, researchers have discovered that it's continuing to cause problems--this time, for dolphins. They've found that bottlenose dolphins in Louisiana's Barataria Bay have lung damage and adrenal hormone abnormalities that were most likely caused by the oil spill.

The Deepwater Horizon spill heavily oiled Barataria Bay. That's why in 2011 the Natural Resource Damage Assessment (NRDA) examined the region in order to identify potential injuries to natural resources and lost public uses resulting from the spill. In all, the researchers sampled 32 dolphins in Barataria Bay. Twenty-nine of these received comprehensive physical examinations, including ultrasounds examinations to assess lung condition.

So what did the scientists discover? It turns out that moderate to severe lung disease was five times more likely in the Barataria Bay dolphins. Symptoms included lung masses and consolidation. In addition, the researchers found that 25 percent of the Barataria Bay dolphins were significantly underweight and the population overall had very low levels of adrenal hormones, which are critical for responding to stress.

"I've never seen such a high prevalence of very sick animals-and with unusual conditions such as the adrenal hormone abnormalities," said Lori Schwacke, one of the researchers, in a news release.

In fact, the dolphins are exhibiting injuries that are consistent with toxic effects seen in laboratory studies of mammals exposed to petroleum hydrocarbons. The fact that these dolphins are so sick, though, doesn't bode well for the overall health of the ecosystem.

The researchers conducting the NRDA studies are actually working closely with the team conducting an Unusual Mortality Event (UME) investigation in the northern Gulf of Mexico under the Marine Mammal Protection Act. Investigations of this type follow stranding events that are unexpected, involve a significant die-off and demand immediate response. Since there's been and observed increase in the number of dolphin strandings, it's more important than ever to assess any of the conditions that may be impacting them.

The findings were published in the journal Environmental Science & Technology.

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