Bottlenose dolphins in the Gulf of Mexico will take 40 years to recover from the effects of the Deepwater Horizon oil disaster, researchers have found.
Numbers of dolphins in the Barataria region of the Gulf in 2020 will be half what they were in 2010 when the Deepwater Horizon rig exploded, killing 11 workers, and releasing 134 million gallons of oil into the sea.
Fresh calculations reveal it will take another 40 years before the dolphins recover, and that a quarter of the remaining population are underweight, with one in seven in a poor or grave condition.
Researchers were, in particular, surprised at how persistent the level of severe lung disease remains among the dolphins.
The spill saw oil contaminate more than 42,000 square miles of the ocean and 1250 miles of coastline. Marine animals were widely affected, either by swimming through oil or by eating other contaminated creatures.
Bottlenose dolphins were among the worse affected and the damage to their health is proving to be of longterm concern.
“Long-term monitoring of these impacted dolphin populations is critical for fully understanding the potential for and timeline of individual and population recovery from a large-scale oil spill event,” a scientific paper into the effects on bottlenose dolphins concluded.
Turtles were also devastated by the spill with scientists concluding that almost a third that were lightly or moderately contaminated died. Those that were heavily oiled suffered a much higher mortality rate.
Results of the international study, led by the US National Oceanic and Atmospheric Administration (NOAA), into the longterm impacts from the spill on marine life were published in a series of papers.
Dr Len Thomas, of the University of St Andrews, was one of the international team involved in the study. He said: “Despite all the uncertainties, it is clear that many populations of marine mammal were badly affected by the oil spill, and that these negative effects will persist for many years into the future.”