Recent research shows that oil is negatively affecting fish genetics and raising concerns about future fish populations in Louisiana waters.
In a paper published in proceedings of the National Academy of Sciences, Fernando Galvez and Andrew Whitehead, who are researchers and assistant professors of biological sciences at LSU, show how oil is affecting fish on a cellular level.
One of the changes caused by this cellular effect is that estrogen signals in fish — needed for healthy reproduction — are being turned way down, Whitehead said.
Another negative development involves fish gills, which are important for fish survival in the highly changeable conditions of Gulf Coast marshes.
“Those gills are very deformed,” Galvez said of recent scientific findings.
Other studies from LSU researchers show that oil contact can cause hundreds of genes to turn “up” or turn “down” — which shows if they’re active or less active.
Some of these changes are a response to oil toxicity and are a survival mechanism, while others are damaging to the fish itself.
Ongoing research continues to look into what long-term effects from last year’s oil spill might have on fish, wildlife and the overall ecosystem.
BP’s Deepwater Horizon rig offshore Louisiana in the Gulf of Mexico blew up on April 20, 2010, and sank two days later, killing 11 workers and touching off the largest offshore oil spill in the nation’s history. The wild well in the Gulf floor a mile below the surface gushed an estimated 200 million gallons of oil before it was brought under control.
In their most recent paper, Whitehead and Galvez first looked at genetic changes in fish by comparing fish samples from areas hit by oil pollution to those untouched by oil pollution.
The collected fish samples didn’t show any components of oil in their tissue or in the water, but fish genes showed telltale signs that the fish had been exposed to oil.
Researchers look at which genes in the fish get “turned on” or “turned off” and this response can tell them what caused that change; in this case, exposure to oil.
Current research is looking at doing this same type of laboratory testing with sediment. Although it’s not been published yet, initial results are showing very large developmental effects, Galvez said.
“Fewer are going on to hatch and hatching is delayed,” Galvez said of fish research findings. “These effects are going to persist.”
After oil gets trapped in sediment, especially if it’s no longer exposed to oxygen, the oil gets stirred up into the water column by storms or weather events, he said.
“It’s going to be continuously exposing these animals to nonlethal effects of hydrocarbons,” Galvez said.
Randy Pausina, assistant secretary of the state Department of Wildlife and Fisheries, said department personnel continue to perform extra monitoring. A $13 million BP grant pays for this, he said.
Since there hasn’t been a full year’s worth of data collected yet, it’s too early to say if any marine populations are seeing problems from oil exposure, he said.
The first species likely to benefit from a full year’s worth of such data-collection efforts probably will be brown shrimp, since the harvesting season has just finished, Pausina said.
Although this type of monitoring doesn’t get as detailed as genetic studies, Pausina said, the department is looking for things such as fisheries deformities or population declines.
Getting a statewide perspective is important because fisheries can fluctuate from year to year and from place to place, he said.
“That doesn’t mean the population of that species is below normal,” Pausina said. “There are other things that move fisheries around.”
However, possible fisheries problems are a concern, in part, because what of what happened to Alaskan fisheries after the Exxon Valdez spill, he said.
Ed Overton, professor emeritus at the department of environmental sciences at LSU, agreed that the real question is not so much what happens in individual areas, but the overall oil spill impact on the ecosystem.
“People didn’t expect the herring population to crash in Prince William Sound (after the Exxon Valdez),” Overton said. “But it did, and there’s still a lot of questions about why that happened.”
Louisiana is seeing a number of research projects and monitoring efforts under way to help try to answer that question.
In addition to the work on the genetic implications of contact with oil, other research is aimed at studying marine fisheries population levels and potential changes to the overall ecosystem.
Kevin Kleinow, a toxicologist at LSU who specializes in environmental health issues related to fish, has been doing research on the possible long-term indirect toxicities of oil on fish in the Gulf of Mexico.
Kleinow’s work looks at the potential impact of the dispersants used during the oil spill emergency, the oil itself and the potential effects on the environment of a combination of oil and dispersant.
Fish didn’t show any abnormalities when exposed to the dispersants, he said.
“Corexit, at least in our system, has minimal effects on development, on abnormalities or mortality,” Kleinow said.
However, the oil did create abnormalities in the fish, he said.
Kleinow said he found a lot of genetic irregularities in fish with direct oil contact — 300 genes either being “turned on” or “turned off” due to oil exposure, although not all the changes are negative.
“Some are genes that would help them (the fish) survive toxic insults. They are survival mechanisms,” Kleinow said.
“If we have fish in one area that’s severely impacted, they may die,” he said.
But in other areas, there may not be any impact, and fish in those locations will thrive, he said.
As a result, there could be an overall balance reached despite effects of oil in certain areas, Kleinow said.