Passing oil pollution from dolphin to calf

The 2010 Deepwater Horizon spill and subsequent oil pollution have had long-term health effects for dolphins, according to new research.

The study, published in the Environmental Journal of Toxicology and Chemistry, found that bottlenose dolphins still had alterations in their immune systems eight years after the spill, with higher levels of some immune cells, and cells that reacted differently in lab studies.

Moreover, the immune alterations were present in dolphins that had been born after the spill.

Exposure to crude oil has been shown to affect the immune systems of many animals, including various types of fish – and even humans. This research suggests that the effects in dolphins have lasted nearly a decade and don’t seem to be diminishing.

“The long-term effects and potential for multigenerational effects raise significant concerns for the recovery of dolphin populations following the spill,” said Sylvain De Guise, lead author on the study.

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Between 2011 and 2018, researchers regularly captured, assessed and released bottlenose dolphins from two bays on the Gulf of Mexico: one (Barataria Bay) had recorded heavy oiling, and the other (Sarasota Bay) had been unaffected by oil.

They found that dolphins from oily areas had higher proliferation of T cells compared to unaffected dolphins. They also found that mice had similar reactions when they – or their parents – were exposed to crude oil in the lab.

De Guise said the research was useful for understanding the effects of oil pollution in mammals, and that in combination with the mice studies “really helped build the weight of evidence between oil exposure and specific effects on the immune system.”

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