The Sarasota Dolphin Research Program played a major role in ground-breaking dolphin health and oil spill research published on 18 December 2013 in the peer-reviewed scientific journal Environmental Science and Technology.
The health of dolphins in Barataria Bay, Louisiana, an area that received heavy and prolonged oiling from the Deepwater Horizon spill, is compared to the health of long-term resident dolphins in Sarasota Bay, Florida, another shallow-water Gulf site, where oil was not observed, to evaluate potential health effects from the oil spill.
Disease conditions in Barataria Bay dolphins were found to be significantly greater in prevalence and severity than those in Sarasota Bay dolphins, as well as those previously reported in other wild dolphin populations. Many disease conditions observed in Barataria Bay dolphins are uncommon, but consistent with oil and oil byproduct exposure and toxicity.
The unique long-term research of the SDRP was crucial for the 2011 project. The SDRP provided data and samples from the Sarasota dolphins as key reference values for the comparison, and SDRP staff assisted NOAA with health assessments in Barataria Bay.
A team of more than 50 government, academic, and non-governmental researchers conducted health assessments as part of the Natural Resource Damage Assessment for the oil spill. Dolphins were temporarily captured, received a veterinary examination, and were then released.
The health exam included measuring each dolphin’s length and weight; doing a physical exam; sampling skin, blood, and blubber; and performing an ultrasound exam to evaluate their internal organs, particularly their lung condition and pregnancy status.
Many of the Barataria Bay dolphins were underweight and their blood tests showed a number of abnormal conditions such as anemia, elevated markers of inflammation, and increased liver enzymes. Dolphins sampled in Barataria Bay showed evidence of very low levels of some hormones (specifically, cortisol) that are produced by the adrenal gland and are important for a normal stress response, consistent with adrenal toxicity as previously reported for laboratory mammals exposed to oil.
Barataria Bay dolphins were 5 times more likely to have moderate to severe lung disease. Of 29 dolphins evaluated from Barataria Bay, 48% were given a guarded or worse prognosis, and 17% were considered poor or grave, indicating that they were not expected to survive, as compared to only one dolphin considered to be in guarded condition in Sarasota Bay. Follow-up research was conducted in Barataria and Sarasota Bays in 2013, and in Mississippi Sound; results are pending.
The research was led by Dr. Lori Schwacke of NOAA’s National Centers for Coastal Ocean Science, and Dr. Teri Rowles, of NOAA’s Marine Mammal Health and Stranding Response Program. SDRP Director Randy Wells and SDRP Staff Scientist Brian Balmer were co-authors on the research article. A PDF of the paper is available from Environmental Science & Technology.
For more information, check out NOAA’s Response and Restoration Blog.