It’s been just over three years since the BP Deepwater Horizon drilling rig in the Gulf of Mexico exploded, killing 11 people and spilling millions of barrels of oil into the Gulf.

An untold number of pelicans and other animals succumbed to the oil slick that polluted large swaths of coast from Louisiana to Florida.

And now researchers are releasing information about impacts that were not immediately lethal, but could affect the coastal ecosystem over time.

Some of this research centers on an oil component called polycyclic aromatic hydrocarbonfound in the soil where the oil came ashore.

This oil component continued to impact Gulf killifish, a type of bait fish, even when oil was no longer visible in the water or the soil, according to a peer-reviewed article in the science journal “Environmental Science and Technology.”

LSU scientists Benjamin Dubansky and Fernando Galvez, with researchers from the University of California, Davis and Clemson University, found that embryos exposed to the previously oiled soil taken from the marsh in August 2011 had problems with deformities.

And, they found that specific genes associated with oil exposure were activated in bait fish Gulf killifish from oil-spattered coastal areas, indicating the fish had been exposed to oil, although the oil component was never found in the fish tissue.

“Other animals show similar effects when they’re exposed to crude oil,” Galvez said.

Research is continuing to see how well embryos that are hatched after contact with the oil-contaminated soil survive and reproduce.

It’s also unknown, researchers said, how well the Gulf killifish located in areas of the coast that were not impacted can make up for possible population declines in the areas that were polluted by the BP oil.

Preliminary research has uncovered similar impacts on insects. Researchers say they can tell if an area has been polluted by oilby the silence when they drive up in a boat.

“What happened after the Deepwater Horizon is when we came to marsh impacted by the oil, they were relatively silent,” said Linda Hooper-Bui, associate professor in the Department of Entomology at LSU.

She and other researchers found there was something in the air killing the insects, possibly the oil components naphthalene and methylnaphthalene, both of which are insecticides.

Eugene Turner, Boyd Professor at the LSU School of the Coast and Environment, found that, for some reason, the two compounds were increasing in the soil even though they should be venting to the atmosphere. Research into why and how that is happening continues.

Another team with the Coastal Water Consortium is examining the disaster’s ongoing effects on birds, specifically the seaside sparrow.

The researchers are looking at how birds in oiled areas compared to birds in unaffected areas in terms of health, genetic stressors, feeding, the success in birds hatching and caring for young, and other issues.

It will take time before those results will be available.

Although the immediate threat to wildlife dying — especially those animals that were covered in oil — has largely passed, researchers are finding that lingering effects are emerging.

Amy Wold covers environmental issues for The Advocate. Follow her on Twitter at @awold10 or email her at