The 2010 Deepwater Horizon oil spill in Florida is most likely the reason for skin lesions and other abnormalities in fish that Florida fisherman discovered almost immediately following the catastrophe.

Scientists from the University of South Florida (USF), the Florida Institute of Oceanography (FIO) and the Florida Fish and Wildlife Research Institute (FWRI) discovered the chemicals that were found in the fish sampled from the Gulf of Mexico closely resemble those found in the waters after the oil spill in 2010.

Steven Murawski, a professor of population dynamics and marine ecosystem analysis at USF’s College of Marine Science, and colleagues were able to rule out the possibility that such skin lesions were the result of pathogens in the water.

“The higher rates of skin lesions in 2011 vs. 2012 were not due to an outbreak of pathogens or abnormally low salinity, and thus the hypothesis that DWH was responsible for the higher rates of skin lesions remains viable,” said Murawski in a statement.

By 2012, the incidence of skin lesions in fish declined by 53 percent, as the oils have dissipated.

The scientists looked at a class of chemicals called polycyclic aromatic hydrocarbons (PAHs), which are typically the most toxic parts of crude oil. Red snapper fish that were found near the explosion had elevated levels of PAHs in their livers and muscles that strongly resembled those released from the oil rig. As the chemicals appeared to decline by 2011 and 2012, the scientists were able to determine that the lesions and abnormalities in fish off Florida’s coast were related to an exposure to pollution.

According to BP, hydrocarbons leaked into the Gulf of Mexico after a gas release and explosion occurred on the Deepwater Horizon oil rig, which also killed 11 people and injured many others.

The findings of the study are published in Transactions of the American Fisheries Society.