More than 675 dolphins have been stranded in the northern Gulf of Mexico since February 2010, and a recent study by the National Oceanic and Atmospheric Administration (NOAA) suggests that oil is to blame. The NOAA conducted extensive physicals on 32 live dolphins in Louisiana’s Barataria Bay who received prolonged exposure to oil from the Deepwater Horizon disaster, and found them to be “incredibly ill” and showing symptoms “consistent with those seen in other mammals exposed to oil.” The NOAA partnered with several organizations to conduct the study and found that almost all the dolphins were underweight and anemic, with low blood sugar. Many had symptoms of liver or lung disease and nearly half have abnormally low levels of the hormones that help with their stress response, metabolism and immune function.
The NOAA study is part of the ongoing Natural Resource Damage Assessment following Deepwater Horizon, and while the agency has not yet confirmed that the dramatic increase in dolphin mortality and illness is a direct result of the Deepwater Horizon Disaster, the implications of the study are pretty clear. Barataria Basin, which encompasses Barataria Bay and sits to the north of the blown out well, “received heavy and prolonged exposure to oil during the Deepwater Horizon oil spill,” according to the NOAA. The area has remained closed to commercial fishing as evidence of the spill remains present on shorelines in the area.
The Barataria dolphins were compared against a control study of dolphins in Sarasota Bay, Florida with the NOAA finding that the symptoms of illness are not showing up “in dolphins from the unoiled area and have not been seen in previous studies of dolphins from other sites.” Furthermore “there is no evidence that two of the most common causes of previous dolphin die-offs in the Gulf, morbillivirus and marine biotoxins, are the cause of this Unexplained Mortality Event.” The NOAA lists that dolphins can be exposed to oil through inhalation of vapors, ingestion of oil from sediment or water, from eating whole fish and via absorbtion through skin, leaving the animals vulnerable on a huge number of counts, and providing a devestating reminder of just how polluted the Gulf now is. The NOAA expects the study of this Unexplained Mortality Event in the Gulf’s bottlenose dolphin population to be complete in six months.
Images courtesy NOAA