Written By: Emma Websdale
Bottlenose dolphins living in an area deeply affected by 2010’s Gulf of Mexico oil spill are suffering from lung disease and adrenal hormone abnormalities, according to U.S. government scientists.
This government study, led by scientists from the National Oceanic and Atmospheric Administration (NOAA) and the National Centers for Coastal Ocean Science (NCCOS), makes the strongest link to date between dolphin death or disease and toxic exposure to oil.
To evaluate the potential sublethal effects of oil toxins on the health of dolphins, health assessments were carried out on 32 dolphins in Barataria Bay, Louisiana, an area heavily inundated with oil after an explosion at the Deepwater Horizon drilling platform in the Gulf. Dolphins were also sampled in a reference site, Sarasota Bay, Florida, where no oil was present, in order to compare health levels.
The two groups undertook this study as follow-up to the worst offshore oil spill in U.S. history, when the equivalent of approximately 4.2 million barrels was released into the Gulf of Mexico. The April 2010 oil spill spread across open water and contaminated more than 1,000 miles of coastline.
Results, published in the journal Environmental Science & Technology, showed that disease conditions found in the dolphins at Barataria Bay (using methods including ultrasound to assess lung condition) were significantly greater in prevalence and severity than those found in dolphins in Sarasota Bay.
Moderate to severe lung disease was five times more likely in the Barataria Bay dolphins, with symptoms including lung masses and consolidation. Seventeen percent of the Barataria Bay dolphins were classified as being in poor or grave condition, meaning that the dolphins were not likely to survive. Meanwhile, twenty-five percent of the dolphins were found to be significantly underweight and to have very low levels of adrenal hormones, meaning they are less able to cope with and respond effectively to stress.
“I’ve never seen such a high prevalence of very sick animals – and with unusual conditions such as the adrenal hormone abnormalities”, says Lori Schwacke, the study’s lead author.
According to EcoWatch, the number of animal strandings since the 2010 disaster along the Gulf Coast from the Texas/Louisiana border has totaled over 1,050, with 94% of the stranded animals dead.