University scientists have received the final round of grants to study the effects of the Deepwater Horizon oil spill on Louisiana’s marshes. Researchers were awarded $4.8 million over the next two years under the umbrella of Coastal Waters Consortium.
The Deepwater Horizon oil spill of April 20, 2010 was the largest in history, with about 5 million barrels of oil spilled into the Gulf of Mexico according to Pew Research Center.
The principal investigator of this award is Department of Oceanography & Coastal Sciences professor Nancy Rabalais.
“Louisiana has always had oil and gas development, and has always had the potential of contamination,” Rabalais said. “One of the things is that the oil contaminant levels have not gotten back to pre-oil spill levels. They’ve declined, but it looks like we have a new baseline which I expect we’ll be at for a long time.”
A large contingent of University scientists will participate in the consortium’s work, including LSU College of the Coast & Environment faculty R. Eugene Turner, Edward B. Overton, Michael Polito, Giulio Mariotti, Dubravko Justic and Haosheng Huang. LSU AgCenter faculty Sabrina Taylor and Philip Stouffer and scientists from several other U.S. universities will also participate. The group was successful in being one of eight funded consortia among a field of 23 submissions, according to a news release.
“We’re studying the movement of oil, salinity, currents and water movement because we want to know how the oil moves within it,” Turner said. “We’re also looking at the chemistry of the oil, how it’s changed over time and its effects on the biology, which includes migratory birds, seaside sparrows, algae, larger plants in marsh, and the chemistry of soil and how it’s recovering.”
The success of seaside sparrow nests declined after the oil spill, but appear to be back to normal according to Rabalais. Researchers have found evidence that the sparrows were trying to metabolize oil.
“We’ve measured maybe a hundred times, a thousand times more oil in some places in the marsh than was in that background of already oiled marsh, and so were watching that decline over time,” Turner said. “Part of that decline is because it’s getting buried and because it’s being decomposed. Right now, the oil concentration might be 95 or 96 percent gone, but on the other hand, it’s still ten times higher than what it was.”
One of the effects of the toxicity of oil exposure was that there was about three times faster erosion in the first year or two. However, it seems to have slowed down, Turner said.
“You can see some obvious effects of the spill on marsh vegetation that was killed immediately,” Rabalais said. “There are longer term effects in erosion and other areas that look like they might be fine, but the root systems are not.”
Studies have shown that fish can sense where there is oil and will migrate away from it, making it difficult to study the population. Researchers also are studying the interactions between the food web.
Rabalais has researched the effects of the oil spill on oxygen conditions. She has found there is no evidence the oil spill made the dead zone worse.
“Just looking at a marsh doesn’t tell you if it’s healthy,” Rabalais said. “We’re doing multiple measures to determine marsh health. It’s recovered enough that animals are using it, populations are coming back in, but it hasn’t returned to pre-2010.”
