The massive oil leak in the spring of 2010 devastated coastlines along the Gulf of Mexico and its effects will likely continue. A new study published in PLoS One has suggested another possible outcome from the spill.
Between June 2010 and June 2013, there were mass strandings of dead or dying dolphins in the region of the spill. From Texas along the shoreline to Florida over 1,000 dolphins died. Scientists compared these deaths to the number of deaths in earlier years and found that not only were there more deaths, but the causes were not the same.
Examinations of the dolphins showed adrenal glands that had atrophied and shrunk as well as tumors in the lungs. These findings were different from the causes of death in other dolphin strandings before the BP accident.
"The dolphins have adrenal disease and lung disease consistent with exposure to petroleum products," explains Stephanie Venn-Watson, lead author of the study. Dr Venn-Watson is also a veterinarian at the National Marine Mammal Foundation in San Diego and has extensive experience with dolphins.
In order to make sure their research was considering all possibilities, the team looked at other factors in addition to the oil spill. A marine virus known as morbillivirus can often cause dolphin deaths, as can toxic algae or colder than normal temperatures.
The team was able to compare tissue analysis from 46 dolphins who died in the region of the spill with the tissues from dead dolphins in other parts of the country not impacted by the spill. 106 dolphins from North and South Carolina as well as parts of Texas and Florida that were not affected by the Deep Water blowout were also examined and the dolphins from the Gulf area had significantly abnormal adrenal glands and lungs that were weakened.
The data collected also matched similar studies of living dolphins in Louisiana who had been exposed to the oil from the underwater well. Those dolphins had reduced lung capacity, and adrenal gland dysfunction.
The study found that the dolphins in the Gulf coast area had a higher likelihood of dying from infections than dolphins in other parts of the country. Without a properly functioning adrenal system, the dolphins had low amounts of cortisol and could not fight off stress and bacteria.
Because dolphins take very deep breaths right at the surface of the water where oil floats, they inhale hydrocarbons from the petroleum which then cause severe lung lesions. BP denies the link between the spill of 2010 and the mass deaths for the following three years according to a statement from their spokesman Geoff Morrell.
A complication of the research findings is that bottlenose dolphins in the Gulf are routinely exposed to petroleum because of the number of wells in the area and there isn't a lot of data on their health before the accident. Still, Dr. Venn-Watson said in a statement about the findings, "The extensive evidence leaves no feasible alternative causes to explain the timing, location and nature of these unusual and deadly conditions."
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