‘”I’ve never seen such a high prevalence of very sick animals …”
By Summit Voice
FRISCO — Dolphins exposed to heavy doses of oil from the Deepwater Horizon disaster are experiencing lung disease at five times the rate of dolphin populations in other areas, federal researchers reported in a new study published this week. The scientists also found that 25 percent of the Barataria Bay dolphins were significantly underweight and the population overall had very low levels of adrenal hormones, which are critical for responding to stress.
“I’ve never seen such a high prevalence of very sick animals — and with unusual conditions such as the adrenal hormone abnormalities,” said lead author Dr. Lori Schacke, who announced similar findings in March 2012.
These findings are in contrast to dolphins sampled in Sarasota Bay, Florida, an area not oiled by the Deepwater Horizon spill.
Oil leaking from the wrecked Deepwater Horizon drilling operation resulted in extensive pollution in Barataria Bay. newly published findings resulted from an August 2011 as part of the Natural Resource Damage Assessment by a team of government, academic and non-governmental researchers. In the NRDA process, federal and state trustee agencies working cooperatively with BP identify potential injuries to natural resources and lost public uses resulting from the spill, along with restoration projects to ensure that the public is fully compensated for its loss.
The publication details the first evidence that dolphins in heavily oiled areas are exhibiting injuries consistent with toxic effects observed in laboratory studies of mammals exposed to petroleum hydrocarbons. The dolphin health study concludes that the health effects seen in the Barataria Bay dolphins are significant and likely will lead to reduced survival and ability to reproduce.
Twenty-nine of the total 32 dolphins sampled in Barataria Bay received comprehensive physical examinations, including ultrasound examinations to assess lung condition. The researchers assigned almost half (48 percent) of the dolphins a guarded or worse prognosis. In fact, they classified 17 percent as being in poor or grave condition, meaning the dolphins were not expected to survive.
The researchers examined alternative hypotheses for the dolphins’ disease conditions, such as exposure to other man-made chemicals that have previously been measured in high concentrations in marine mammals and also associated with impacts on health. Blubber samples from the Barataria Bay dolphins, however, showed relatively low concentrations for the broad suite of chemicals measured, including PCBs and commonly detected persistent pesticides, as compared to other coastal dolphin populations.
Based on the findings from the 2011 dolphin health study, researchers performed three additional health assessments in 2013 as part of the Deepwater Horizon NRDA. The studies were repeated in Barataria Bay and Sarasota Bay, and also expanded to Mississippi Sound, including both Mississippi and Alabama waters. Results from these more recent health assessments are still pending.
The research was linked with investigations into unusual mortality events, required under the Marine Mammal Protection Act. The observed increase in the number of dolphin strandings now includes more than 1,050 animals that have stranded along the Gulf Coast from the Texas/Louisiana border through Franklin County, Florida. Ninety-four percent of these animals have stranded dead.
The UME investigation, spanning from February 2010 to present, is the longest UME response since 1992, and includes the greatest number of stranded dolphins in an UME in the Gulf of Mexico. Dr. Teresa Rowles, lead for the Marine Mammal Health and Stranding Response Program and a co-author on the dolphin health publication, said that “these dolphin health studies will contribute significant information for both the NRDA and the UME investigation as we compare disease findings in the wild, living dolphins to the pathologies and analyses from the dead animals across the northern Gulf.”
Funding for the study was provided by BP and NOAA has shared the data with BP, and they had observers present at the health assessments. They were not, however, involved in any way in the analysis and interpretation of the data nor in the drafting of the paper.