By Cameron McWhirter
Most of the dolphins in the northern Gulf of Mexico that have
died since the 2010 Deepwater Horizon oil spill suffered severe
health problems consistent with petroleum exposure, according to a
study backed by the federal government and published in a
scientific journal Wednesday.
BP PLC, the main operator of the well that spilled, disputed the
paper's findings, saying the scientists had found no link between
the oil spill and the dolphin deaths.
The paper, published in the peer-reviewed online scientific
journal PLOS One, focused on 46 bottlenose dolphins found dead from
2010 to 2012 in waters off the coasts of Louisiana, Mississippi and
Alabama, which had been hit by the oil spill. The scientists found
most of the animals had lesions in their lungs and adrenal glands
that caused many to die by disturbing their ability to regulate
metabolism and blood pressure, and weakening their ability to fight
infection.
The animals all had "significant life-threatening abnormalities"
that were "consistent with the effects of petroleum products," said
Kathleen Colegrove, a veterinary pathologist from the University of
Illinois who participated in the research.
Ms. Colegrove said some of the dolphins died of bacterial
pneumonia. The severity of the disease in the bodies was the worst
she had ever seen in 13 years of studying dead dolphins, she
said.
Dolphins are highly susceptible to chemical exposure, and
infections are more likely because they have large lungs, she
said.
Stephanie Venn-Watson, a veterinary epidemiologist with the
National Marine Mammal Foundation in San Diego who participated in
the research, said the scientists could find "no remaining feasible
alternative causes" for the lesions except petroleum exposure from
the Deepwater Horizon spill.
BP issued a statement saying the study proved no connection
between the disaster and the dolphin die-off, which actually began
several months before the oil spill. The National Oceanic and
Atmospheric Administration lists the die-off as having started in
February 2010, while the spill was in April.
"Correlation is not evidence of causation," wrote BP spokesman
Geoff Morrell.
The paper published Wednesday follows previous studies
suggesting a connection between the oil spill and a dolphin die-off
in the gulf. In 2013, scientists with NOAA published a paper
showing that living dolphins in Barataria Bay, La., showed severe
lung diseases associated with oil contamination.
In April 2010, an explosion occurred on the Deepwater Horizon
drilling rig about 40 miles off the Louisiana coast, after a
blowout of a well 5,000 feet below the ocean surface. BP was a
majority owner of the well. Over 87 days, oil slicks spread across
open water and fouled more than 1,000 miles of coastline. It was
the worst offshore oil spill in U.S. history.
The study is part of a process led by NOAA called Deepwater
Horizon Natural Resource Damage Assessment. If studies find a link
between the spill and any damage, BP will be expected to pay
compensation, though the company can appeal findings in court.
Ms. Colegrove said research on dolphins in the area where the
oil spill occurred will continue.
"It really could be many years before we receive the full
effects of the oil spill on the dolphin populations," she said.
Write to Cameron McWhirter at cameron.mcwhirter@wsj.com
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