US dolphins’ sickness caused by oil

Dolphins in Barataria Bay, an estuary in Southeast Louisiana that suffered heavy, long-term exposure to oil from the 2010 BP oil spill, are sick.

Researchers with the National Oceanic and Atmospheric Administration on Friday discussed the preliminary results of a study of 32 Barataria Bay dolphins. The study is part of continuing investigations into the Gulf of Mexico Dolphin Unusual Mortality Event and the Deepwater Horizon Oil Spill Natural Resource Damage Assessment.

“We found the dolphins overall are not in good health,” said Lori Schwacke, lead investigator, NOAA Ocean Services Oceans and Human Health branch chief. “Some are very sick.”

The dolphins studied in early August 2011 suffered various health problems, including being underweight, being anemic, having low blood sugar and displaying signs of liver or lung disease, Schwacke said.

About half had low adrenal hormone levels, including the stress hormone, which can cause low blood sugar, weight loss and can lead to death, she said.

The low hormone levels suggest adrenal insufficiency, which has not been seen in other dolphins, including those in a control group from Sarasota Bay, Fla., or along the Atlantic coast, Schwacke said.

Many are in such poor health they’ll probably die, she added.

“We don’t know definitely that the health concerns are connected with oil exposure,” Schwacke said.

But similar problems with adrenal glands have been found in studies of mink doused in oil, she said.

The NOAA findings are preliminary and further study will be done to help scientists better understand oil exposure, Schwacke said. But the findings thus far are consistent with the findings of other studies of the effect of oil exposure on mammals.

Scientists also are studying dolphin strandings along the Gulf of Mexico coast, said Teri Rowles, NOAA Fisheries National Marine Mammal Health and Stranding Response program coordinator.

Dolphin stranding levels in Louisiana, Mississippi and Alabama remain high nearly two years after the BP spill, but strandings along the Florida panhandle have returned to pre-spill levels, Rowles said.

More than 1,000 dolphins have been recorded in Barataria Bay. Between February 2010 and March 18, more than 180 dolphins were found stranded along the shoreline of three parishes edging the bay, including Jefferson, Lafourche and Plaquemines parishes, she said.

Normally, the annual average of strandings in Louisiana as a whole from 2002 to 2009 was 20.

The results are preliminary and researchers are uncertain if they are connected with exposure to oil from the BP spill, Schwacke said.

Ben Sherman, public information officer with NOAA, urged caution in extrapolating that these test results apply to dolphins elsewhere in the Gulf of Mexico.

“The results presented today only reflect what we know about the health of dolphins in Barataria Bay area of Louisiana,” he wrote. “They may provide possible clues to other dolphins exposed to oil in the northern Gulf of Mexico. However, it is too soon to tell how the Barataria Bay findings apply to the overall UME or to the health implications for other dolphins exposed to oil in the Gulf of Mexico.”


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