By Eugenie Samuel Reich of Nature magazine

It was one of the most dramatic sightings ever made in an aerial survey of the Arctic: a dead polar bear, bloated like a gigantic beach ball, floating in open water north of the Beaufort Sea coastline in Alaska.

Researchers say that they spotted four dead polar bears during the survey, and surmised that the bears drowned in stormy waters as they searched for ever-receding sea ice. The idea that polar bears could drown like this became a rallying point for advocates of action on climate change, most notably appearing in former US vice-president Al Gore's film An Inconvenient Truth (2006).

Now, five years after the observations were reported, the bears have become the focus of charges ranging from scientific fraud to political interference in science. Last week, it emerged that the US Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) had suspended a researcher involved in the survey, wildlife biologist Charles Monnett. The reason, according to an 18 July memo from Monnett's supervisor, Jeffrey Loman, was an investigation into "integrity issues" by the Office of the Inspector General (OIG) at the US Department of the Interior, which oversees the BOEMRE. Climate-change skeptics were quick to jump on the news as evidence that the science of global warming had been distorted. The BOEMRE has also halted a different polar-bear survey overseen by Monnett, pending further investigation.

Monnett's suspension was brought to light on 28 July by Public Employees for Environmental Responsibility (PEER), a watchdog group in Washington DC that is giving Monnett legal advice in the matter.

PEER released a transcript of an interview between criminal investigators at the OIG and Monnett, in which Monnett was told that he had been accused of scientific misconduct. He was then asked a series of questions relating to the paper in which he had reported the four drowned polar bears (C. Monnett and J. S. Gleason Polar Biol. 29, 681-687; 2006), but was not told the specific allegations.

Jeff Ruch, executive director of PEER, says that this does not conform with the Department of the Interior's scientific-integrity policy, which states that those accused of misconduct should be properly informed of the allegations against them, and that the allegations should be referred to a scientific-integrity official, not to criminal investigators. On 29 July, PEER filed a scientific and scholarly misconduct complaint against Monnett's superiors and the OIG, accusing them of violating the policy.

Ruch claims that the suspension is a politically motivated attack on Monnett's research at a time when the BOEMRE is considering whether to allow an expansion of oil drilling off Alaska's northern coast. The bureau denies this, and any accusation of playing into the oil industry's hands is highly sensitive, because the bureau (then known as the Minerals Management Service) was accused of poor oversight of the industry leading up to the Deepwater Horizon oil spill in the Gulf of Mexico in 2010. Ruch adds that Monnett is declining interviews because he has not been granted permission to do them by the bureau.

"Any accusation of playing into the oil-industry's hands is highly sensitive."

After a day of negative publicity generated by PEER's announcement, the bureau hit back. Spokeswoman Melissa Schwartz says that, contrary to the impression given by the transcript, Monnett's suspension was unrelated to scientific-integrity issues, his polar-bear finding or oil-drilling permits. She declined to say what it was related to.

But a 13 July memo to Monnett, provided to Nature by PEER, says that the investigation had uncovered information that raised concerns about his ability to act "in an impartial and objective manner" while handling a US$1.1-million contract for a study of polar bears in the Canadian Arctic. A notice sent to Monnett by the OIG on 29 July further explained that although investigators may continue to query him on scientific integrity, they will now focus on how Monnett awarded the research contract. This includes questions over whether Monnett complied with the Federal Acquisition Regulation, which is intended to ensure fair competition for US government contracts. The OIG adds that the inquiry is not criminal in nature, as the Department of Justice has already considered the case and declined to prosecute. Ruch says that Monnett's handling of the contract was transparent to his supervisors, and that his technical role meant he was not responsible for compliance with the regulation.

The project, begun in 2005, involves putting radio collars on polar bears found on the Canadian side of the Beaufort Sea, and tracking their position by satellite over several seasons. The study is funded by various sources, including the BOEMRE and the Canadian government. But on 13 July, the BOEMRE told scientists on the project to stop their work. The project's principal investigator, Andrew Derocher, a biologist at the University of Alberta in Edmonton, Canada, says he had no idea why. "To begin with, I thought it was related to budgetary issues in the United States. I've never seen anything like this in my life," he says.

Derocher says that data should continue to come in from collars until 2013, but the 'stop work' order may mean that he is unable to document his findings in a final report to the agency. Among those findings is that 2-4-year old polar bears tend not to stray far from their home range--the first time this age group has been tracked. This would mean that in the event of a large oil spill, bears that died from oil exposure would not be replaced quickly by bears from surrounding areas, says Derocher.

Drowned polar bears have not been reported by other scientists, but the hypothesis that a long search for sea ice makes it more likely that bears will get caught in stormy weather and drown is regarded as plausible. In January, scientists led by George Durner at the US Geological Survey in Anchorage, Alaska, reported the fate of an adult female bear as she swam more than 600 kilo­meters before reaching ice (G. M. Durner et al. Polar Biol. 34, 975-984; 2011). When the researchers caught up with the animal, she had lost 22% of her body mass and her year-old cub.

This finding, corroborated by other studies, suggests that the major impact of receding sea ice on the bears is nutritional stress caused by a reduction of their hunting range, says Steven Amstrup, chief scientist at the campaigning organization Polar Bears International, headquartered in Bozeman, Montana, and a co-author of the study. But the observation that drowning can occur is important, he adds. "If this investigation is not about those observations then the BOEMRE owes it to him and to the public to say clearly what it is about."

Update: On 2 August, BOEMRE spokeswoman Melissa Schwartz told Nature that the order to stop work on Derocher's polar bear study was rescinded on 1 August, and that work is continuing again. Derocher confirms he has received a notice to proceed.

This article is reproduced with permission from the magazine Nature. The article was first published on August 2, 2011.