The National Oceanic and Atmospheric Administration and its partners are working together on the Natural Resource Damage Assessment (NRDA). Part of NRDA’s charge is to evaluate the long term impacts of the Deepwater Horizon oil spill on dolphins in the Gulf.
One of the studies, conducted in August 2011, focused on dolphins in Barataria Bay off Louisiana. The Bay was chosen because it was heavily oiled for a prolonged time during the Deepwater Horizon spill. They also sampled dolphins in Sarasota Bay, Florida, an area not oiled by the spill.
Health assessments were conducted on 32 dolphins from Barataria Bay who were examined and released. Twenty nine of them received comprehensive examinations, including ultrasound examinations to assess lung condition. Moderate to severe lung diseases associated with oil contamination were prevalent among many of the dolphins. Almost half of the dolphins were given a guarded or worse prognosis and 17 percent were not expected to survive. They were found to be underweight, have low hormone levels, low blood sugar and some showed signs of liver damage. The control group in Sarasota Bay was not found to have elevated lung diseases.
On December 18, 2013 the peer reviewed study, which was disputed by BP, was published in the journal Environmental Science & Technology. It details the 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 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.
Lori Schwacke, the study’s lead author and a wildlife epidemiologist at NOAA said “it is related to oil, the weight of the evidence is there.”