20 May 2015 (PBS) – JUDY WOODRUFF: Now: the lasting impact of America’s biggest offshore oil spill.
It comes as officials are grappling with a new spill along the coast of Southern California near Santa Barbara. It began yesterday when an onshore pipeline ruptured. Slicks are now spanning a total of nine miles and the line was operating at full capacity when it broke.
Today, a new study by researchers at the National Oceanic and Atmospheric Administration looked at why dolphins died in such large numbers after the Deepwater Horizon spill of 2010. It was the strongest link yet to the spill and to the deaths of bottlenose dolphins. More than 1,000 dolphins have died in the Gulf since 2010.
The spill lasted nearly three months, spewing millions of gallons of oil and chemicals into the Gulf of Mexico.
We get the latest from William Brangham, who weekend viewers will recognize, and he is now here with us as our newest NewsHour correspondent.
And we welcome you to the team, William.
WILLIAM BRANGHAM: Thanks, Judy. Great to be here.
JUDY WOODRUFF: So, let’s talk about this, what researchers are saying. What do they say these new studies show?
WILLIAM BRANGHAM: What they’re saying is that this has been the first definitive link where they can directly connect the death, this massive die-off of dolphins — as you mentioned, over 1,300 — I think it’s 1,200, 1,300 dolphins — linking those deaths directly with the oil spill.
I mean, scientists have been studying these dolphins for several years, ever since the spill occurred. This is the first time they have said, we now know why they died and in such large numbers, and it’s because of the Deepwater Horizon disaster.
JUDY WOODRUFF: Now, BP is pushing back, of course. They are saying there’s no proof that there’s a connection to the oil that came out of the Deepwater Horizon rig. What do scientists say about that?
WILLIAM BRANGHAM: That’s true.
This has been BP’s argument all along, and in fact they have also pointed out that there were die-offs of dolphins that happened all the time on the Gulf, and that actually some of these dolphins had died off before the spill even occurred.
But scientists went to great lengths today to say that they looked at all the other factors that have caused die-offs in the past, and that this particular spill, the impact the oil has had on marine mammals, they can directly connect it to the dolphins that they have seen. And, in fact, the research that they did showed in the areas where there was more oil in the water, more dolphins died, areas where there was less oil, less dolphins died.
JUDY WOODRUFF: Now, are the bottlenose dolphins still dying off, or was this a one-time phenomenon?
WILLIAM BRANGHAM: The deaths have occurred ever since the spill began all the way to the present day. The current study only looked at a couple of years after the spill.
And what they did is, they examined 46 particular dolphins that died, and they were quickly able to catch them on the beaches of the Gulf. And they analyzed their tissues and found lung and adrenal gland problems. So this is — they think this may be an ongoing problem, but this study just looked at this particular period.
JUDY WOODRUFF: And do they offer an explanation for why they’re seeing this with the bottlenose dolphins, but not with other animal species, crab, fish, shrimp, and so forth?
WILLIAM BRANGHAM: The impact on those other species may occur. They just haven’t found the data on them yet.
The reason that dolphins, the scientist says, are the — are particularly acute sort of ways to understand this is that, if you think about how a dolphin lives, they’re mammals. They breathe air. So during the spill, they come to the surface to breathe the — to breathe. They enter the area of the water where the oil is sitting, and so they take a huge, deep breath with their blowhole, suck oil and chemicals into that.
Then they take a deep dive and hold that breath for a very long period of time. So, they’re particularly able to, in essence, suck in the oil and cause great deals of problems. Also, the scientists were able, to all throughout the spill, find these dolphins. They were able to go out and find them. They’re very large mammals swimming around in the water. [more]
20 May 2015 (NOAA) – As part of an unusual mortality event investigation, a team of scientists has discovered that dead bottlenose dolphins stranded in the northern Gulf of Mexico since the start of the Deepwater Horizon oil spill have lung and adrenal lesions consistent with petroleum product exposure according to a paper published today in the peer-reviewed online journal PLOS ONE.
These findings support those of a 2011 health assessment of live dolphins in Barataria Bay, Louisiana, a heavily oiled area during the spill which showed those resident dolphins had poor health, adrenal disease, and lung disease.
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. Increased dolphin deaths following the oil spill are part of the northern Gulf of Mexico unusual mortality event investigation.
“This is the latest in a series of peer-reviewed scientific studies, conducted over the five years since the spill, looking at possible reasons for the historically high number of dolphin deaths that have occurred within the footprint of the Deepwater Horizon spill,” said Dr. Teri Rowles, veterinarian and one of 22 contributing authors on the paper, and head of NOAA’s Marine Mammal Health and Stranding Response Program, which is charged with determining the causes of unusual mortality events, also known as UMEs. “These studies have increasingly pointed to the presence of petroleum hydrocarbons as being the most significant cause of the illnesses and deaths plaguing the Gulf’s dolphin population. This study carries those findings significantly forward.”
Direct causes of death, during this period, likely included:
Chronic adrenal insufficiency resulting from adrenal gland effects;
Increased susceptibility to life-threatening outcomes due to adrenal insufficiency, especially when challenged with pregnancy, cold temperatures, and infections; and
Increased susceptibility to primary bacterial pneumonia, possibly due to lung injury, or alterations in immune function.
Animals with untreated adrenal insufficiency are at risk of life-threatening adrenal crises. The adrenal gland produces hormones – such as cortisol and aldosterone – that regulate metabolism, blood pressure and other bodily functions.
“Animals with adrenal insufficiency are less able to cope with additional stressors in their everyday lives,” said Dr. Stephanie Venn-Watson, the study’s lead author and veterinary epidemiologist at the National Marine Mammal Foundation, “and when those stressors occur, they are more likely to die.”
Since early 2010, there has been an ongoing cetacean unusual mortality event involving primarily bottlenose dolphins in the northern Gulf of Mexico. Three out of four groupings of elevated dolphin strandings identified within this event followed the Deepwater Horizon oil spill.
This ongoing die-off, with the highest number of dead bottlenose dolphin strandings on record in the northern Gulf of Mexico, coincided with the largest marine-based oil spill in the United States.
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.
“These dolphins had some of the most severe lung lesions I have seen in the over 13 years that I have been examining dead dolphin tissues from throughout the United States,” said Dr. Kathleen Colegrove, the study’s lead veterinary pathologist based at the University of Illinois. In comparison, only 2 percent of reference dolphins had these lesions.
In other mammals, exposure to petroleum-based polycyclic aromatic hydrocarbons, known as PAHs, through inhalation or aspiration of oil products can lead to injured lungs and altered immune function, both of which can increase an animal’s susceptibility to primary bacterial pneumonia. Dolphins are particularly susceptible to inhalation effects due to their large lungs, deep breaths and extended breath hold times.
The prevalence of Brucella and morbillivirus infections, which were investigated as potential alternative causes for increased dolphin deaths, was low in UME dolphins after the oil spill and was no different compared to the reference dolphins. Additionally, biotoxin levels were either low or below the detection limit in the UME dolphins.
Ongoing studies assessing changes in these lung and adrenal gland lesions over time will help to address questions regarding how long these chronic conditions may last.
The study team included representatives from NOAA’s National Marine Fisheries Service, NOAA’s National Ocean Service, the National Marine Mammal Foundation, the University of Illinois, the University of Georgia, the Dauphin Island Sea Lab and University of South Alabama, the Institute for Marine Mammal Studies, Gulfport, Mississippi; the Louisiana Department of Wildlife and Fisheries, the Audubon Aquarium of the Americas, New Orleans; the Mote Marine Laboratory, Sarasota, Florida; the Texas Marine Mammal Stranding Network, Galveston; and the Marine Mammal Pathology Services, Olney, Maryland.
This work 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.