National Geographic News
The dorsal fin of a dolphin is seen as clean-up workers collect tar balls of oil along a stretch of oil-contaminated beach June 14, 2010 in Grand Isle, Louisiana.

The dorsal fin of a dolphin appears behind workers collecting tar balls of oil on a Louisiana beach June 14, 2010. A new study links the Gulf oil spill to higher incidences of health problems for bottlenose dolphins in the area.


Ker Than

For National Geographic

Published December 20, 2013

Dolphins living in an area heavily impacted by the 2010 Deepwater Horizon oil spill show higher incidences of lung disease, hormonal abnormalities, and other health effects, a new study finds.

The research, led by U.S. government scientists and funded by BP, the oil company that operated the ill-fated Macondo well, provides the clearest evidence to date linking the oil disaster with potentially deadly health effects in bottlenose dolphins in the Gulf of Mexico. (See related quiz: "How Much Do You Know About the Gulf Oil Spill?")

The dolphin study was done as part of a process led by the U.S. National Oceanic and Atmospheric Administration (NOAA) called a Natural Resource Damage Assessment that investigates whether the spill was responsible for any damage to wildlife or natural resources.

"I've never seen such a high prevalence of very sick animals—and with unusual conditions such as the adrenal hormone abnormalities," study leader Lori Schwake, a NOAA scientist,  said in a statement. (See related, "Gulf Oil Spill Pictures: Ten New Studies Show Impact on Coast.")

Mobi Solangi, who directs the Institute for Marine Mammal Studies (IMMS) in Gulfport, Mississippi and was not involved in the study, called the study a "good first step [that] shows the possibility of a link," he said. (See related, "Dolphin Baby Die-Off in Gulf Puzzles Scientists.")

Toxic Oil Effects

For the study, the scientists compared the health of dolphins in Louisiana's Barataria Bay, which was heavily oiled during the April 2010 spill that spewed an estimated 5 billion of barrels of crude oil into the Gulf, with another dolphin population living farther away, in Sarasota Bay, Florida, one year after the spill, in 2011. (Related: "The Next Oil Spill: Five Needed Mandates to Head it Off" and "Gulf Spill Dispersants Surprisingly Long-lasting")

About 30 dolphins in Barataria Bay were caught, examined and released. The checkups included an ultrasound examination to assess the animals' lung conditions. The researchers concluded that many of the dolphins suffered from moderate to severe lung disease associated with oil contamination. Almost half had "a guarded or worse prognosis, and 17 percent were considered poor or grave, indicating they weren't expected to live," according to the study, which was published in the journal Environmental Science & Technology.

The researchers also found that the Barataria Bay population overall had very low levels of adrenal hormones, which are critical for responding to stress, and that 25 percent of the dolphins were significantly underweight.

The team also noticed other disturbing signs. "We had one animal that was actually pregnant, but the fetus was nonviable," Schwacke told National Geographic.

"There was no heartbeat or movement and it looked like it may have been dead a week or so ... The interesting thing was the stage of pregnancy was the second trimester. A lot of the things that you think of that causes abortions in dolphins hits in the third trimester. So seeing something like that in the second trimester is unusual, and it's certainly consistent with a toxic effect." (See related story: "BP Oil Spill's Sticky Remains Wash Up Sporadically on Gulf Beaches")

In contrast, the control group of 15 dolphins in Sarasota Bay which was not affected by the oil spill did not show elevated levels of lung disease or other health effects.

Apples and Oranges

BP spokesperson Jason Ryan disputed the study's findings, saying that the symptoms the scientists observed in their study has been seen in other dolphin mortality events that have been linked to contaminants and conditions found in the northern Gulf, including "PCBs, DDT and pesticides, unusual cold stun events, and toxins from harmful algal blooms."

"The symptoms are also consistent with natural diseases such as Morbillivirus and Brucellosis," Ryan said in an email.

Moreover, he added, dolphin mortality events occur with some regularity in the Gulf of Mexico and around the world and have for years.

But NOAA's Schwacke said her team did take steps to rule out the possibility of other factors being responsible for the dolphin's poor health.

"We looked at a broad suite of contaminants, including PCBs and DDT...and the levels in Barataria were actually lower than in Sarasota Bay," she said.

An online statement by BP also criticized the scientists' decision to compare dolphins in Barataria Bay with those living Sarasota Bay. "The two populations are genetically different and the environments are different," the statement reads.

"Barataria Bay is much more industrialized and has experienced numerous oil and fuel spills over the years, as well as the release of other contaminants. Sarasota Bay dolphins had been captured and sampled for health assessments and other measurements for many years. They were much more used to being around people and to being captured-released than were the Barataria Bay dolphins, and this may have resulted in more stress to the Barataria Bay animals."

'No Doubt'

Solangi of IMMS said that BP's criticisms of the study were valid, especially the point about the two dolphins group not living in comparable habitats.

"It would be like comparing a population [of people] living in the [United States] with a population in Africa or South America. You can't do that," Solangi said.

Nevertheless, Solangi said he has no doubt that the 2010 oil disaster played a role in the dolphins' health declines.

"There's no question in my mind that the oil is a contributing factor. It's the elephant in the room," he said.

Schwacke said her team is already seeking funding for a followup study in Barataria Bay next summer that will look at the same dolphin population, and perhaps even the same individuals if any of them are alive. (Related Photos: "Gulf Oil Spill: Oiled Beaches Timeline")

The new findings come in a week when BP announced its first significant oil discovery in the Gulf of Mexico since the Deepwater Horizon spill. The discovery, at its Gila prospect, which it co-owns with ConocoPhillips, is about 300 miles (482 kilometers) southwest of New Orleans, and in a lease block called Keathley Canyon, roughly 200 miles southwest of the Mississippi Canyon lease block that held the Macondo well. BP has previously announced two other discoveries in the same geological formation as Gila, the Paleogene trend, Kaskida in 2006 and Tiber in 2009. BP's plans for development in the Tiber in 2010 were derailed by the Macondo spill. (Related Photos: "Four New Offshore Drilling Frontiers")

BP said that the Gila discovery "is a further sign that momentum is returning to BP's drilling operations and well execution in the Gulf of Mexico," said Richard Morrison, regional president of BP's Gulf of Mexico business.

Follow Ker Than on Twitter.

This story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.

tayib colen
tayib colen

NOAA states in their 2010 to 2013 Cetacean report: that there has been Unusual Mortality event for dolphins and whales in the Northern Gulf of Mexico from Feb 2010 to present.

As of December 15 2013 1,062 whale strandings in the Northern Gulf of Mexico - 6% stranded alive and 94% DEAD.

Taeyoung Kim
Taeyoung Kim

Even though green energy sources have been discovered and invented continuously, natural resources for our livings at present account for the distinct percentages of the entire energy source. This means that we cannot help but to explore and develop the remaining resources such as oil, and therefore, this kind of disaster can take place at anytime on earth until the near future when only green every sources are used for every our living. To prevent catastrophic incidents like this disaster, governments should be much more strict about any mistake by companies concerning critical contamination on the environment. Of course companies should be aware of the consequences of their mistakes which are irremediable.

manfred humphries
manfred humphries

Gee, do you think it might have something to do with the toxic junk BP dumped on the oil to make it sink?  What a dumb strategy.

Victo A.
Victo A.

This is heartbreaking. And the bottlenose dolphin is a "protected species." Now Anadarko Petroleum Corp, which owned part of the blown out well at the center of the 2010 Gulf of Mexico oil spill, has come to drill for oil and gas in deepwater off New Zealand. They're almost finished drilling off Taranaki, have started drilling off Raglan (New Zealand's surfing mecca) and are about to start drilling in the turbulent waters off Otago and Southland (the Canterbury Basin, from Oamaru to Invercargill). They will start immediately off Dunedin, NZ's wildlife capital, where endangered Royal Northern Albatross, Yellow Eyed Penguins and Hooker's Sea Lions breed. Southern Right Whales migrate through these waters. Dolphins, including endangered Hector's Dolphins, are often seen along this coast. Fur Seals, Little Blue Penguins, Giant Petrels, Stewart Island Shags, Fairy Prions, Sooty Shearwaters, Black-backed Gulls, Buller's Albatrosses and many other species are also regularly spotted here.
Dunedin is located at 45.8667° latitude, in the "roaring forties," where gale force winds blow throughout the year. NZ is also vulnerable to earthquakes. It's a veritable recipe for disaster.
Protests have taken place throughout NZ, but the govt. isn't listening. In fact, it has passed a draconian law against protesting near oil platforms. Will what happened—and apparently is still happening­—in the Gulf of Mexico, occur in New Zealand? 

storm eden
storm eden

why do we continually destroy our environment when free clean energy can be had by  all

Louisette Lanteigne
Louisette Lanteigne

NOAA states in their 2010 to 2013 Cetacean report: that there has been Unusual Mortality event for dolphins and whales in the Northern Gulf of Mexico from Feb 2010 to present. As of December 15 2013 1,062 whale strandings in the Northern Gulf of Mexico - 6% stranded alive and 94% DEAD.

If it's big enough to kill a WHALE, think of impacts to people and fisheries. 

Louisette Lanteigne
Louisette Lanteigne

It's like a greenwash to simply state they are ill. Many are actually DEAD as a result. Let's get that data in here. And while we are on the topic, why not do coverage of the Lubicon Cree by the Tar Sands where miscarriage rates are 19 in every 21 births. They are suffering severe upper respiratory tract illnesses and cancers.  What about Sarnia Ontario next to Tar Sands refineries where the average life span is 47 years. Their cancers mirror the ones seen in Fort Chipewyan. 

People are dying and dolphins are dying. Let's go there. Tell the story as it is and not glaze it over to make it nice. Tell the truth based on actual facts and science. 

R Smoak
R Smoak

Gotta love the fact that the consumer probably footed the bill for this "research" because BP just raised the per gallon price by a couple cents hahaha only in America

R Smoak
R Smoak

It is amazing how self-centered we are.  If a single human had been killed or had their property irreversibly damaged this would be a different story.

Louisette Lanteigne
Louisette Lanteigne

@R Smoak PEOPLE DIED already. 11 died when the rig exploded. Many more are dealing with issues of toxicity. 


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