Dolphins living off the coast of Louisiana during and after the massive Deepwater Horizon oil spill in 2010 have genetic changes that could serve as a “canary in the coal mine” for future disease, according to researchers who analysed the animals’ blood samples.

“[Gene expression] is a very, very sensitive indicator that can let us know something’s going wrong long before we see illness or deaths in the population,” says at GEL Laboratories in South Carolina, who worked at the National Marine Mammal Foundation at the time of the study.

The largest marine petroleum spill, the Deepwater Horizon disaster churned around 800 million litres of crude oil into the Gulf of Mexico after an oil rig sank in April 2010. The impacts on wildlife were staggering, with fish, birds and marine animals dying in huge numbers. But the long-term consequences of the spill on wildlife are less understood, which led Morey to investigate how common bottlenose dolphins (Tursiops truncatus) were faring.

She and her team analysed the health records and blood samples of 71 wild dolphins captured and released between 2013 and 2018. During hands-on exams, biologists assessed each animal’s physical health, including their heart and lung function, and performed ultrasounds on pregnant females.

The researchers lacked data on dolphins before the spill, so they compared more than 11,000 genes of individuals living in oil-impacted Barataria Bay, Louisiana, with those from dolphins living in Sarasota Bay, Florida, which was spared from the spill. Some of the Louisiana dolphins lived through the disaster, while others were born after.

The analysis revealed thousands of differences in gene expression in animals in the disaster region compared with those outside the affected area. The gene PRG3, which is linked to declining lung health in humans, was expressed 8.2 times higher in dolphins that lived through the disaster than in those born after. Morey notes that dolphins in the contamination zone that had lung issues documented in their physical exams were more likely to have disruptions in the genes that regulate the growth of new lung tissue. The researchers also found elevated expression of a collection of genes associated with immune responses in dolphins from the contaminated zone.

The greatest differences in gene expression were seen in animals studied in 2013, the date closest to the disaster.

While the researchers were able to draw preliminary links between changes in gene expression and physical health symptoms, they caution that their sample size is small. They also note the difficulty of isolating the damage caused by the spill from damage that may be due to other pollutants in the ocean.

Dolphin deaths

It wasn’t just the coastline and the ocean surface that was drenched in oil after the Deepwater Horizon spill in 2010. Life in the deep sea took a hit, too, and many species in the region are still drastically reduced in number.

“The health of our overall oceans also requires a healthy deep sea, as the deep oceans serve vital roles in carbon cycling, marine food webs, and overall ocean function,” says Craig McClain at the Louisiana Universities Marine Consortium. He and his colleagues used remotely operated underwater vehicles to survey the Gulf of Mexico around the site of the disaster. They did the survey in June 2017 and compared their findings with surveys done in the two months directly after the oil spill.

While the number of animals increased in that time, the diversity was lower. McClain says he and his team noticed an absence of sea cucumbers, fly-trap anemones, Venus flower basket sponges, and giant isopods – crustaceans that look like large woodlice.

There has also been a change in which animals inhabit the area. The communities seen in 2010 and 2017 were less than 20 per cent similar in composition.

Surprisingly, they found an abundance of arthropods, including the red shrimp Nematocarcinus, a white caridean Glyphocrangon shrimp, and the Atlantic deep sea red crab. McClain says they may be attracted to the site because the hydrocarbons that break down in the wake of an oil spill can mimic the chemicals in sex hormones that they use to find mates.

“This seems to be common in some other oil spills. A historic oil spill in Buzzards Bay in New England attracted the American lobster in droves,” he says. “We believe the hydrocarbons are serving as an attractant and creating a La Brea Tar Pit scenario, where healthy individuals are attracted but are trapped, and may eventually die, at the site.”

They may die there because the chemical signals may also deter other animals they prey on from entering the area.

The sampling McClain and his team did were at deeper sites than the Deepwater Horizon well, but he says that at these depths in the Gulf of Mexico, we wouldn’t expect to see much difference in diversity. “We are confident that the differences of the Deepwater Horizon site specifically reflect environmental damage related to the oil spill,” he says.

The number of nests of Kemp’s ridley turtles dropped massively in 2010, when the Deepwater Horizon oil spill happened (Image: Erich Schlegel/Corbis)

There’s something amiss with iconic marine animals in the Gulf of Mexico: sea-turtle populations are in retreat, dolphins are in poor shape and whales are avoiding their usual hunting grounds.

Such long-term effects seem to linger five years on from the largest oil spill in US history, which followed the explosion of the Deepwater Horizon rig on 20 April 2010, killing 11 workers and wreaking havoc on the region’s wildlife.

Following the spill in the north of the Gulf of Mexico, there was a reverse in a sustained two-decade recovery of the world’s most endangered sea turtle – the Kemp’s ridley, which neared .

To what extent the oil disaster is to blame is still under debate, but the matter is shrouded in mystery partly because ongoing litigation over compensation means that few scientists are prepared to discuss their data publicly.

The answer is important because, like other iconic and long-lived marine animals such as sperm whales and dolphins (see box, below), sea turtles are at or near the top of the food chain. What happens to them is therefore a bellwether for potential impacts of the spill on the rest of the marine ecosystem.

Changing fortunes

Most Kemp’s ridleys lay their eggs on beaches in the Tamaulipas region of north-eastern Mexico. A joint Mexican and US conservation programme launched in 1978 had put the turtles on the route to recovery: the number of nests rose by 15 per cent per year on average, from a record low of 702 in 1985 to 21,000 in 2009, with growth accelerating to 19 per cent in the late 2000s.

Then, in 2010, it all started to unravel (see graphic, above). “Suddenly, the number of nests counted at the primary nesting beaches plummeted by nearly 40 per cent,” says of Oregon State University in Corvallis. Although nest numbers rose back up to 2009 levels in 2011 and 2012, they did not resume the increasing trajectory. “Now, the number of nests is declining, with 2014 showing the lowest number since 2006,” says Heppell.

Was the 2010 collapse and slowdown in recovery caused by the spill, or was it a coincidence driven by other factors?

and her colleagues at Texas A&M University in Galveston presented data at a February meeting in Houston, Texas, showing that the turtles stopped foraging on the seabed in areas contaminated by oil. But there’s no proof that this affected survival and precipitated the collapse of nesting numbers.

, president of LGL Ecological Research Associates in Bryan, Texas, and a consultant who has previously helped compile stock reports on Kemp’s ridley turtles, speculates that the collapse was driven by an exceptionally cold year in the northern Gulf. In this area, the turtles forage and gain strength to prepare for their long migration in spring to the breeding beaches in Mexico.

Another possibility is that the turtle population has outgrown the capacity of the gulf to support it.

But Heppell says that such a sudden collapse in 2010 is not consistent with this explanation. “Nest counts alone are not enough to point the finger at BP, as there are a number of things that could affect nest numbers,” she says. However, we’ve never seen such a dramatic drop in one year as in 2010, she adds. Also, the recovery came to an abrupt halt, and didn’t slow gradually as we might expect to happen if it was coming to some sort of environmental carrying capacity.

Status reviewed

Some answers may be forthcoming with the publication later this year of an updated five-year by the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service, and a Red List Assessment report by the marine-turtle specialist group of the International Union for Conservation of Nature.

BP This claimed that the clean-up operation has been a success and that the impacts on wildlife have not been as damaging as some may have anticipated, with the Gulf of Mexico “rebounding”.

The report glossed over the effect on the turtles, claiming that changing trends in nesting “could be due to many factors including natural variability and cold temperatures”.

Conservation groups such as the that paint the opposite picture.

And the Natural Resource Damage Assessment Trustees, including those from NOAA for BP to reach conclusions about impacts from the spill before the completion of the official evaluations .

“There are a number of plausible explanations for the turtle decline, and long-term research is critical to finding out the real answer,” says Gallaway. But from for turtle research and secrecy amid ongoing legal cases against BP, this may prove hard to do. “No one can be forthcoming [with regard to data] because they need permission from whichever side is funding them,” says Gallaway. “A lot of information is therefore not available because of confidentiality agreements.”

Guilty as charged. Yesterday a federal US court found BP grossly negligent in the Deepwater Horizon oil spill, one of the worst environmental disasters in US history. The ruling leaves the oil company liable for up to $18 billion in fines. But four years on, the drilling industry may not have learned any lessons.

After the Deepwater Horizon drilling rig exploded in April 2010, 11 people were killed and millions of barrels of oil leaked into the Gulf of Mexico. The event has had lasting effects for local wildlife like coral and shrimps. BP, , has already spent more than four years and $14 billion on cleaning up the coast.

Yesterday’s court decision lays the lion’s share of the blame at BP’s feet. US district judge found BP 67 per cent responsible for the spill, with contractors and sharing the remainder of the blame. “BP’s conduct was reckless,” wrote Barbier.

Nailed to the wall

The ruling is the company’s “worst case scenario”, says , author of . “Barbier really threw the book at BP.”

The charge of gross negligence means the company may be asked to pay about four times more – $4300 per barrel of oil spilled rather than $1300 – than if it had just been classed as negligence.

In a released later the same day, BP said that they strongly disagreed with the decision and intend to appeal to the US Court of Appeals for the Fifth Circuit.

There are still some uncertainties about the case. A second phase of the trial will determine the exact size of the spill, in order to calculate the size of BP’s fine. The company didn’t closely track the amount of oil at the time, but scientists can estimate it using records of the changing pressure in the oil reservoir and information about the make-up of the surrounding rocks. The US government estimates it was between 4 and 5 million barrels.

No change

Whatever the size of the fine, industry experts say that the judgment is unlikely to lead to large changes in how the oil industry operates.

There have been a few changes in the way the government oversees the industry, says , a petroleum engineer in Dallas, Texas, and an expert witness for the case. For a while, it was more difficult to obtain drilling permits, and there seemed to be an increase in routine inspections of wells.

But overall, Hughett says, the case will probably not lead to major changes. “I don’t think that the ruling changes the mindset of the people that are already involved in that type of work. It may heighten their awareness,” says Hughett. “I don’t see anything in there that would change the way we really fundamentally operate.”

Cavnar agrees. Since the spill, the US Congress has been slow to enact stricter rules for drillers, he says. “We had a moment in time, when this disaster came to the consciousness of the public, that we had a chance of actually getting something done, but it was tamped down so quickly,” says Cavnar. “I’m afraid we’re going to have to get another before we’re going to get through the noise from all the industry money that keeps the government from applying all the industry regulations and safer practices.”

Fancy being an infrared detective? A team of hardware hackers has to dramatically slash the cost of infrared cameras.

The idea behind this Infragram project is to allow anyone to check on the health of plant life. The team says it expects to sell the cameras for around $35, but the price could potentially even be as a low as $10.

At that price any citizen environmentalist could get busy spotting oil or sewage spills in wetlands, for example. And buyers will be able to share their images – and learn infrared tricks – with likeminded users online.

It took Infragram just a week to exceed its stated target of $30,000.

The project involves bulk buying cheap point-and-shoot 2-megapixel digital cameras and fitting them with a “superblue” filter. This forces the red channel of the camera’s image sensor to produce an IR image that will be saved to the camera’s SD memory card.

The founders hatched the idea for Infragram after shooting images of the damage caused to Texan wetlands and coastlines by BP’s Deepwater Horizon oil spill in July 2010. The principle relies on the fact that red light is absorbed by plants during photosynthesis but infrared is not – so healthy plant life should reflect a lot of near infrared light. But if pollution has caused a die back, that won’t be the case.

Until now, professionals doing work like this have used expensive “vegetation stress cameras” created by – costing between . But Infragram hopes to allow gardeners, farmers, activists and students to study such plant stress on the cheap.

The Deepwater Horizon spill has just provided a $400-million windfall for Louisiana’s environment. Transocean, which worked with BP on the stricken Macondo well, pleaded guilty last week to a violation of the US Clean Water Act, and admitted that it was negligent in the 2010 spill. The resulting will be used to pay for around the Gulf of Mexico.

It is the second largest fine for environmental damage in history, after the $4.5-billion fine BP had to pay out for the same spill. Transocean has two years to pay up in full.

The National Academy of Sciences (NAS) will get $150 million, and another $150 million will go to the (NFWF), a non-profit based in Washington DC. The NAS will use its portion to research oil-spill prevention and better ways to respond to spills. The NFWF’s says it will distribute its award between the affected Gulf Coast states, for ongoing remediation efforts such as marsh and wetland clean-up.

The remainder of the money will go directly to Louisiana’s $50-billion , which aims to restore the state’s degraded coastline. The money will fund a host of projects, including restoring barrier islands and creating diversions on the Mississippi to repair eroded coasts.

“The way Louisiana looks at it, their coastal problems are so pervasive that the degradation from the spill was a final indignity,” says DiCintio. The modifications should not only allow the state to rebuild after the lingering effects of the spill and hurricane Katrina, but also help the coast cope with future disasters.

BP HAS been stung for $4.5 billion – the largest criminal fine in US history – and the company could be liable for a further $21 billion in civil damages. The fine handed down by the US Department of Justice last week relate to the 2010 Deepwater Horizon oil rig disaster in the Gulf of Mexico.

Some $2.4 billion of the fine will go to the National Fish and Wildlife Foundation, which will spend the money on conservation projects in the Gulf region.

The crux of the civil damages case lies in whether BP is shown to have displayed “gross negligence”. Under the Clean Water Act, the company would be liable for a $1100 fine for every barrel of oil leaked into the environment, going up to $4300 per barrel in the case of gross negligence. BP leaked 4.9 million barrels into the Gulf over three months, so could be facing a $21 billion fine.

The company said it would “vigorously defend itself” against the civil claims. The civil trial is due to begin early next year.

Public Employees for Environmental Responsibility () alleges that Bill Lehr of NOAA edited his report to stress estimates from a technique called particle image velocimetry, even though three scientists on the team had already concluded that the technique was seriously underestimating the flow.

Their much higher estimates were later confirmed to be roughly correct.

Lehr denies the allegation. “Absolutely nothing was done in any way to change these numbers or fudge any data,” he told Âéśš´ŤĂ˝.