December 19, 2013
BP Spill Affects Dolphin Health Three Years Later
[ Watch the Video: Louisiana Dolphins Still Suffer From BP Oil Spill ]
Brett Smith for redOrbit.com - Your Universe OnlineA team led by scientists from the National Oceanic and Atmospheric Administration (NOAA) has linked the 2010 BP oil spill in the Gulf of Mexico to lung damage and adrenal hormone abnormalities in bottlenose dolphins inhabiting Louisiana’s Barataria Bay.
Study researchers based their findings on health assessments conducted more than one year after the spill. Both dolphins in the bay, as well as a comparison group near Sarasota, Florida were examined for the study. While the Louisiana bay was one of the most heavily-oiled areas after the spill, the Florida locale did not receive any observable oil.
"Many disease conditions observed in Barataria Bay dolphins are uncommon but consistent with petroleum hydrocarbon exposure and toxicity," the study team wrote in their report, which was published Wednesday in the journal Environmental Science & Technology.
The researchers gave 48 percent of 29 bay dolphins that were examined a guarded prognosis or worse, and 17 percent were considered in poor or grave condition. These dolphins were expected to die as a result of their illness.
“I’ve never seen such a high prevalence of very sick animals — and with unusual conditions such as the adrenal hormone abnormalities,” study author Lori Schwacke, a researcher with NOAA and the Medical University of South Carolina.
The researchers said some of the dolphins’ symptoms were consistent with those seen in previous oil-related studies involving other animals.
"The decreased cortisol (hormone) response is something fairly unusual but has been reported from experimental studies of mink exposed to fuel oil," the report said. "The respiratory issues are also consistent with experimental studies in animals and clinical reports of people exposed to petroleum hydrocarbons.”
The dolphins were examined in August 2011 – 16 months after the April 20, 2010 explosion at the Deepwater Horizon oil rig that killed 11 workers. After the explosion, an underwater oil gusher sent an estimated 4.9 million barrels of oil into the surrounding waters until it was capped on July 15.
"The severe disease documented by this study and the continued elevation of mortalities raise significant concerns regarding both short-term and long-term impacts on the Barataria Bay dolphin population," the study said.
BP has yet to formally admit that the oil spill has played any role in premature dolphin deaths.
"The symptoms that NOAA has observed in this 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," a representative told The Huffington Post.
However, the researchers did test blubber samples from the Louisiana dolphins and found fairly low amounts of common pesticides, PCBs and other chemicals. The study authors did concede in their report that the symptoms found in their dolphin subjects could be explained by natural causes.
One "cannot dismiss the possibility that other pre-existing environmental stressors made this population particularly vulnerable to effects from the oil spill," the authors wrote.