A study published earlier this year suggested that the oil that lingers in the Gulf of Mexico continues to pose a threat to local ecosystems. The study by Florida researchers indicates that About 3,243 sq miles (8,400 square km) of the sea floor is still covered with oil from the disaster.
"This is going to affect the Gulf for years to come," Jeff Chanton, the study's lead researcher and a professor of chemical oceanography at Florida State University, said in a statement.
This study corroborates an October study which found that as much as 30 percent of the spilled oil remains on the ocean floor.
"Fish will likely ingest contaminants because worms ingest the sediment, and fish eat the worms. It's a conduit for contamination into the food web."
CBS news quoted the study’s lead researcher, Jeff Chanton, as saying: ‘This is going to affect the Gulf for years to come.
‘Fish will likely ingest contaminants because worms ingest the sediment, and fish eat the worms. It's a conduit for contamination into the food web.’
Dolphins and turtles in the Gulf are dying in record numbers. Bottlenose dolphins have been dying at more than twice the normal rate over the past five years and the nesting habits of the endangered Kemp's Ridley sea turtle changed dramatically around the time of the spill. Commercial fisheries have also seen a reduced yield.
The BP oil spill was an unprecedented disaster and after five years 2 percent of samples of water and seafloor sediment continue to exceed federal toxicity levels. According to research from the Associated Press the overall health of the Gulf of Mexico has declined 11 percent since April 2010.
The research suggests that lingering impacts of the BP oil spill in the Gulf are being felt by tuna and other species that spawned in oiled offshore habitats in the northern Gulf of Mexico. A Stanford NOAA study revealed that the spill is causing severe defects in the developing hearts of Atlantic bluefin, yellowfin tunas and an amberjack species. The study shows that crude oil exposures is slowing the heartbeat or causing an uncoordinated rhythm in these fish, which can ultimately lead to heart failure.
"We know from the 1989 Exxon Valdez spill in Prince William Sound that recently spawned fish are especially vulnerable to crude oil toxicity," said Nat Scholz, Ph.D., leader of the ecotoxicology program at NOAA’s Northwest Fisheries Science Center in Seattle. “"That spill taught us to pay close attention to the formation and function of the heart."
"This fits the pattern," said Dr. John Incardona, NOAA research toxicologist and the study’s lead author. "The tunas and the amberjack exposed to Deepwater Horizon crude oil were impacted in much the same way that herring were deformed by the Alaska North Slope crude oil spilled in Prince William Sound during the Exxon Valdez accident."
"The timing and location of the spill raised immediate concerns for bluefin tuna," said Barbara Block, Ph.D., a study coauthor and professor of biology at Stanford University. "This spill occurred in prime bluefin spawning habitats, and the new evidence indicates a compromising effect of oil on the physiology and morphology of bluefin embryos and larvae."
The culprit in the heart defect appears to be oil-derived polycyclic aromatic hydrocarbons (PAHs). PAHs can persist for many years in marine habitats and cause a variety of adverse environmental effects. Other observed morphological abnormalities on oil-exposed larva were also revealed in the study. This includes poor growth of fins and eyes.
"We now have a better understanding why crude oil is toxic, and it doesn’t bode well for bluefin or yellowfin embryos floating in oiled habitats.” said Block. “At the level of a single heart muscle cell, we’ve found that petroleum acts like a pharmacological drug by blocking key processes that are critical for cardiac cell excitability."
The authors further suggest that other species like cardiac-related impacts on swordfish, marlin, mackerel and other Gulf species may also be impacted cardiac abnormalities if they spawned in proximity to oil.
Experts say it could take "decades" for the ecosystem to recover.
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