Half of Bottlenose Dolphins in Barataria Bay Sick or DyingClean Water, Land & Coast
Blog Home | Half of bottlenose dolphins in Barataria Bay were seriously ill or dying in 2011, new study finds

By Mark Schleifstein, NOLA.com | The Times-Picayune

December 18, 2013

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Nearly half the bottlenose dolphins in Barataria Bay tested in mid-2011 to assess natural resources’ damage in the aftermath of the BP Deepwater Horizon oil spill were in “guarded or worse” condition, including 17 percent that were not expected to survive, according to a peer-reviewed study released Wednesday morning.

The study by a team of government, academic and non-governmental researchers found that the marine mammals had lung damage and abnormally low amounts of hormones produced by their adrenal glands at levels not previously seen in other dolphin populations. Researchers examined dolphins in the heavily oiled Barataria Bay, including the area around Grand Isle.

The dolphin’s hormones would have been expected to be at elevated levels as a result of the way the 29 animals were corralled in the water for testing, “including a brief chase, encirclement with a net, and restraint by a team of human handlers,” according to the report. Instead, nearly half the Louisiana dolphins had low levels of adrenal gland hormones.

Those abnormalities were not found in bottlenose dolphins tested in Sarasota Bay, Fla., chosen as a comparison reference site because it was not contaminated with oil from BP’s 2010 Macondo well blowout.

“I’ve never seen such a high prevalence of very sick animals – and with unusual conditions such as adrenal hormone abnormalities,” said Lori Schwacke, the lead author of the study, in reference to the Barataria Bay dolphins.

The study appeared in Environmental Science and Technology, a journal published by the American Chemical Society. Schwacke, a wildlife epidemiologist and research statistician with NOAA’s Hollings Research Laboratory in Charleston, S.C., has been that agency’s lead investigator for dolphins in the aftermath of the spill.

A BP spokesman Wednesday disputed the results of the study, saying the dolphin illnesses could have other causes, including contamination by man-made chemicals pre-dating the spill or natural illnesses, and criticized federal officials for not providing the company with data backing up the poor health findings.

But in a news conference Wednesday afternoon, NOAA scientists said BP officials were provided with data from the study and actually were present during the dolphin testing in Barataria Bay in 2011.

And they said the evidence supports exposure to the BP oil, and not to other chemicals or natural illnesses, as the key factors in the poor health of the Louisiana dolphins.

The study said that previous research has found that dolphins and other cetaceans, such as whales, “appear to be able to detect the presence of oil but do not necessarily avoid it.”

“In the months following the DWH spill, dolphins were observed in oiled waters, including (bay, sound and estuary) waters, at times swimming through surface oil and with oil adhering to their skin,” the study said. “Dolphins therefore had potential for exposure to oil through direct contact at the surface and in the water column, through incidental ingestion from water or sediments while feeding, and through ingestion of contaminated prey.

“In addition, dolphins breathe immediately above the air-water interface and thus can be exposed to volatile and aerosolized petroleum-associated compounds through inhalation,” the study said. But it said that while dolphin and whale deaths had been suggested as being caused by prior oil spills, the data proving that link has been lacking.

In the new study, the researchers also found that moderate to severe lung disease was five times more likely in the Barataria Bay dolphins than those in Florida. Symptoms among the Louisiana dolphins included lung masses.

A quarter of the Barataria Bay dolphins also were significantly underweight.

As part of the study, the researchers looked at alternate hypotheses for the disease symptoms the dolphins were experiencing, including exposure to other man-made chemicals previously found in high concentrations in marine mammals.

Samples of blubber taken from the Baratara Bay dolphins showed relatively low concentrations of those chemicals, including PCBs, dioxin and other persistent pesticides, when compared to dolphin populations found elsewhere.

The researchers said that while more research should be done on other potential causes for some of the illnesses seen in the dolphins, in most cases, those illnesses could be the result of exposure to oil from the spill.

For instance, the adrenal hormone profiles found in the Louisiana dolphins also were found in mink in an experimental study in which they were fed either bunker C oil or artificially weathered fuel oil.

In the case of the lung problems, the scientists found that some dolphins in Sarasota Bay had similar symptoms. But those Sarasota dolphins were juvenile animals, and their symptoms were mild and found to be linked to either a lungworm infection or pneumonia caused by vermin. The Louisiana dolphins with lung problems included fewer juvenile animals and their symptoms were found to be moderate to severe, and not consistent with lungworm infection.

The study said their problems could be the result of bacterial, fungal and viral infections that could be related to an underlying lung injury.

“The lung disease observed in (Barataria Bay) dolphins is consistent with laboratory studies and clinical reports of humans and animals exposed via ingestion, inhalation or aspiration to petroleum hydrocarbons,” the study said, adding that the findings “are consistent with exposure to oil resulting in either primary lung injury and secondary pneumonia, or primary aspiration pneumonia.”

While the researchers felt some other infectious agent was an unlikely cause of the lung problems, they recommended additional studies of stranded dolphins to rule out the possibility.

The study also found liver abnormalities in the Louisiana dolphins, and compared them to similar abnormalities in sea otters exposed to oil during the Exxon Valdez oil spill in Alaska in 1989 and to similar abnormalities among Deepwater Horizon oil spill cleanup workers.

Researchers conducted three more dolphin health assessments in 2013 as part of the Natural Resource Damage Assessment program. Those included additional tests of animals in Barataria Bay and Sarasota Bay, as well as in Mississippi and Alabama waters. The results from those tests are pending, according to a news release announcing the publication of the 2011 study.

The study points out, however, that dolphin deaths actually began being reported in February 2010, before the BP oil spill. Those deaths had prompted the federal government to launch an “unusual mortality event” investigation in the northern Gulf of Mexico under the federal Marine Mammal Protection Act.

That event has continued until now, with more than 1,050 marine mammals, including 913 bottlenose dolphins, stranded from the Texas/Louisiana border through Franklin County, Fla. Of the stranded animals, 94 percent died. NOAA officials said the event has lasted longer than any similar die-off since 1992, and includes the greatest number of stranded dolphins in any Gulf mortality event.

“These dolphin health studies will contribute significant information for both the NRDA and the (unusual mortality event) investigation as we compare disease findings in the wild, living dolphins to the pathologies and analyses from the dead animals across the northern Gulf,” said Dr. Teresa Rowles, a co-author of the study and leader of the NOAA Marine Mammal Health and Stranding Response Program.

But the researchers said Wednesday that the paper’s findings relate only to the dolpins in Barataria Bay, and not to the larger mortality event.

The study’s findings will be used as part of the Natural Resource Damage Assessment process required under the federal Oil Pollution Act of 1990. Federal and state trustees identify potential injuries to natural resources and the lost use of public resources caused by the spill, and identify restoration projects that will compensate the public for the lost resources.

In a statement issued early Wednesday, BP spokesman Jason Ryan pointed out that the company has been paying for the NRDA research, and has repeatedly requested access to the dolphin health data.

“The agency still has not provided BP with any data demonstrating that the alleged poor health of any dolphins was caused by oil exposure,” Ryan said. “Indeed, NOAA has not even provided BP an injury assessment on dolphins or any other species or habitat.”

Ryan said the symptoms identified in the NOAA study “have been seen in other dolphin mortality events that have been related to contaminants and conditions found in the northern Gulf, such as PCBs, DDT and pesticides, unusual cold stun events, and toxins from harmful algal blooms.”

He said the symptoms also are consistent with those found in dolphins suffering from diseases such as morbillivirus and brucellosis, and also noted the mortality event began almost three months before the Macondo well blowout.

“In fact, dolphin (unusual mortality events) occur with some regularity in the Gulf of Mexico and around the world, and have for years,” Ryan said.

In October 2011, pathology experts contracted by NOAA confirmed that five dolphins found dead in Louisiana waters or stranded on beaches during the mortality event were infected with brucellosis, a bacterial infection better known in the United States for killing cattle, bison and elk.

At that time, the researchers said they didn’t know whether the spilled oil played a role in those deaths, which included three fetuses and two dolphins, or in the deaths or strandings of other dolphins.

But Dr. Stephanie Venn-Watson, a veterinary epidemiologist and chairwoman of a working group studying the mortality event, said at the time that the oil could be working in tandem with the bacteria in increasing the illness of the dolphins.

“The dolphins may be more susceptible to severe infection because their immune system is not working well, or the pathogen, Brucella, becomes stronger and thus are able to do more damage,” she said then.

During the Wednesday news conference, Rowles said the investigation of the Northern Gulf unusual mortality event is ongoing, but researchers have already ruled out morbillivirus and evidence doesn’t indicate that biotoxies, such as from algae blooms, are the cause.

“We have no evidence at this time that brucellosis is the overarching cause of the unusual mortality event in the northern Gulf, but at this point, we don’t have a factor that we can pinpoint as the causitive agent,” she said. “But we cannot rule out the role of BP oil in this unusual mortality event.”


The research team for the study included scientists from Louisiana State University, Cornell University and the universities of South Carolina and Tennessee; National Marine Mammal Foundation of San Diego, Calif.; Chicago Zoological Society; Howard Hughes Medical Institute, Bayside Hospital for Animals in Fort Walton Beach, Fla.; and several researchers from NOAA’s National Ocean Servie and National Marine Fisheries Service.

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