Star marine ecologist committed misconduct, university says

A major controversy in marine biology took a new twist last week when the University of Delaware (UD) found one of its star scientists guilty of research misconduct. The university has confirmed to Science that it has accepted an investigative panel’s conclusion that marine ecologist Danielle Dixson committed fabrication and falsification in work on fish behavior and coral reefs. The university is seeking the retraction of three of Dixson’s papers and “has notified the appropriate federal agencies,” a spokesperson says.

Among the papers is a study about coral reef recovery that Dixson published in Science in 2014, and for which the journal issued an Editorial Expression of Concern in February. Science—whose News and Editorial teams operate independently of each other—retracted that paper today.

The investigative panel’s draft report, which Science’s News team has seen in heavily redacted form, paints a damning picture of Dixson’s scientific work, which included many studies that appeared to show Earth’s rising carbon dioxide (CO₂) levels can have dramatic effects on fish behavior and ecology. “The Committee was repeatedly struck by a serial pattern of sloppiness, poor recordkeeping, copying and pasting within spreadsheets, errors within many papers under investigation, and deviation from established animal ethics protocols,” wrote the panel, made up of three UD researchers.

Dixson did not respond to requests for comment. She “adamantly denies any and all allegations of wrongdoing, and will vigorously appeal any finding of research misconduct,” Dixson’s lawyer, Kristina Larsen, wrote in an email to Science. Larsen describes Dixson as a “brilliant, hardworking female scientist” who was “targeted” by a group of scientists who “chose to ‘convict’ Dr. Dixson in the court of public opinion” by sharing their accusations with a Science reporter last year. “Their vigilante approach all but assured Dr. Dixson would never be able to receive a fair and impartial review elsewhere,” Larsen writes. UD says it will not comment on Dixson’s future there.

The accusations against Dixson have sharply divided marine ecologists, with some scientists suggesting the whistleblowers acted out of professional envy or to advance their own careers. The accusations were “stalking and harassment” and “one of the most disgusting and shameful things I‘ve ever seen in science,” John Bruno, a marine ecologist at the University of North Carolina, Chapel Hill, tweeted in March. (Bruno—who wrote a commentary accompanying Dixson’s 2014 Science paper—did not respond to an email informing him of UD’s findings.)

UD “did a decent investigation. I think it’s one of the first universities that we’ve seen actually do that,” says ecophysiologist Fredrik Jutfelt of the Norwegian University of Science and Technology, one of the whistleblowers. “So that’s really encouraging.” But he and others in the group are disappointed that the committee appears to have looked at only seven of the 20 Dixson papers they had flagged as suspicious. They also had hoped UD would release the committee’s final report and detail any sanctions against Dixson. “That is a shame,” Jutfelt says.

Pioneering research

Dixson is known as a highly successful scientist and fundraiser. She obtained her Ph.D. at James Cook University (JCU),  Townsville in Australia, in 2012; worked as a postdoc and assistant professor at the Georgia Institute of Technology for 4 years; and in 2015 started her own group at UD’s marine biology lab in Lewes, a small town on the Atlantic Coast. She received a $1.05 million grant from the Gordon and Betty Moore Foundation in 2016 and currently has a $750,000 career grant from the National Science Foundation (NSF). She presented her research at a 2015 White House meeting and has often been featured in the media, including in a 2019 story in Science.

Together with one of her Ph.D. supervisors, JCU marine biologist Philip Munday, Dixson pioneered research into the effects on fish of rising CO₂ levels in the atmosphere, which cause the oceans to acidify. In a series of studies published since 2009 they showed that acidification can disorient fish, lead them to swim toward chemical cues emitted by their predators, and affect their hearing and vision. Dixson’s later work focused on coral reef ecology, the subject of her Science paper.

The whistleblowers, an international team of academic researchers in marine biology, had long questioned the very big effect sizes and unusually small variances in data reported by the pair. In a 2020 Nature paper, the whistleblowers reported they could not reproduce several of the claims in their own studies. Later that year, four of them decided to ask for a misconduct investigation into the work, as Science reported. They directed the request at three funding agencies that had backed studies by Munday and Dixson, including the U.S. National Institutes of Health and NSF, but those agencies apparently asked UD and Georgia Tech to investigate.

In its undated draft report, UD’s 3-person investigative committee concludes Dixson simply did not have enough time to collect the vast amount of data described in the 2014 Science paper, co-authored with Georgia Tech marine ecologist Mark Hay. It purported to show that overfished, seaweed-covered reefs in Fiji fail to attract juvenile individuals of 15 fish and three coral species.

Like most of Dixson’s experimental work, the study relied partly on a so-called choice flume, an apparatus in which a fish can choose whether to swim toward a chemical signal. The committee calculated that to produce the paper’s data, which Dixson said she had collected herself, she would have had to carry out 12,920 fluming trials, generating some 860,000 data points and taking 1194 hours of observation time. The ecologist would have needed 11,628 liters of sea water to flow through the flume, which the draft report says she had to collect 2 kilometers from the shore. “It is highly unlikely that she had the time available to do all the experiments and trials as detailed in the paper,” the panel wrote.

The draft report also confirms claims by the whistleblowers and independent statistical experts consulted by Science’s News team that a large Excel file containing the study’s raw data was riddled with inexplicably duplicated columns. “Numerous errors are also present within the data files such that the results presented in the publication could not be generated from these files,” it says.

Hay, Dixson’s supervisor at the time, says he wasn’t in Fiji during the study because of other obligations. But Dixson “was among the most hard-working and persistent colleagues I’ve worked with,” and the amount of data reported in the paper “did not seem unreasonable given Dr. Dixson’s time in Fiji and strong work ethic,” he says. Hay says he has not seen the panel’s report, but “if UD found fault with her studies, I’m surprised.” Dixson “had good intuition, good field skills, and seemed honest and genuine,” he says.

Hay says he was interviewed by a separate investigation committee at Georgia Tech but does not know the status or the outcome of that investigation. A Georgia Tech spokesperson did not respond to requests for comment.

Science Editor-in-Chief Holden Thorp says Dixson, Hay, and the third author, David Abrego of Zayed University in Abu Dhabi, United Arab Emirates, all declined to sign the retraction notice for the Fiji study, after which Science’s editors decided to retract the paper themselves. Dixson and Hay published another paper in Science in 2012 showing corals can “recruit” plant-eating fish to trim toxic seaweeds. “We have been discussing the 2012 paper but were not given any information about it by the university,” Thorp says, “so we will begin our usual process to determine whether retraction or correction is warranted.”

A corrected paper

The draft report also found misconduct in a 2016 paper on whether anemone fishes can sniff out the condition of potential host anemones, published in Proceedings of the Royal Society B by Dixson and marine ecologist Anna Scott of Southern Cross University in Australia. Again, the timeline was implausible, the committee concluded. Collecting the data would have taken 22 working days of 12 hours, it wrote, “working continuously without any breaks or doing any preparation work, recalibration, cleaning, bucket switchouts,” and so on. Yet the paper said the study was done in 13 days, between 12 November and 24 November 2014.

Scott and Dixson posted a correction to the Proceedings B paper in early July, stating that the studies actually took place between 5 October and 7 November 2014, adding 20 days to the timeline. The correction also says two flumes were used simultaneously, effectively doubling the observation time. (Dixson reported using two flumes simultaneously in other studies as well, according to the investigative committee, which wrote it was “at a loss to understand” how she could keep an eye on two animals and record positions for both every 5 seconds.)

Along with the correction to the Proceedings B paper, Dixson and Scott uploaded an Excel file containing the raw data for the study, which had been missing. (The paper said it was available on Southern Cross University’s institutional repository). But the whistleblowers say that file also has many duplications and other problems.

Scott, a former president of the Australian Coral Reef Society, tells Science she signed off on the correction. She did not respond to questions about UD’s misconduct findings or the alleged problems in the data set. Spencer Barrett, editor-in-chief of Proceedings B, says an investigative panel made up of three editors approved last month’s correction. But since then, UD has been “in touch” about the paper, he says, and the panel will discuss the issue again. He says Proceedings B is also investigating another paper by Dixson.

The committee noted that a 2014 paper in Nature Climate Change co-authored by Dixson and Munday also “had serious issues regarding the datasheet files, with patterns of copying and pasting of datasheets,” which it called “signatures of fabrication and falsification of data.” But it’s unclear from the redacted draft report whether it thinks that paper should be retracted. On another paper co-authored by Munday, in Animal Behaviour in 2012, the panel notes its results show “extreme effect sizes and low to zero variance” but says, because no notebooks or files exist from the study, “there is insufficient evidence to support a finding of research misconduct.” For similar reasons the panel did not conclude there was misconduct in a paper Ecology Letters in 2009 on which Munday was also a co-author. Munday, who has retired from JCU, says he is “shocked to hear the outcome of the investigation” but declined to elaborate.

Josefin Sundin of the Swedish University of Agricultural Sciences, a member of the group of whistleblowers, says the research culture at JCU, a tropical marine biology mecca, deserves more scrutiny. Sundin and others earlier blew the whistle on a 2016 Science study, which was also retracted; that paper’s first author, Oona Lönnstedt, also obtained her Ph.D. at JCU under Munday’s co-supervision. “We have heard many stories about an unhealthy focus on eye-catching publications at JCU. The competition level is extremely high,” Sundin says.

Great bravery

Several former members of Dixson’s lab supported the whistleblowers’ request for an investigation. One of them, former postdoc Zara Cowan, was the first to identify the many duplications in the data file for the now-retracted Science paper. Another, former Ph.D. student Paul Leingang, first brought accusations against Dixson to university officials in January 2020. He left the lab soon after and joined the broader group of whistleblowers.

Leingang, who had been at Dixson’s lab since 2016, says he had become increasingly suspicious of her findings, in part because she usually collected her fluming data alone. In November 2019 he decided to secretly track some of Dixson’s activities. He supplied the investigation with detailed notes, chat conversations, and tweets by Dixson to show that she did not spend enough time on her fluming studies to collect the data she was jotting down in her lab notebooks.

The investigative panel found Leingang’s account convincing and singled him out for praise. “It is very difficult for a young scholar seeking a Ph.D. to challenge their advisor on ethical grounds,” the draft report says. “The Committee believes it took great bravery for him to come forward so explicitly. The same is true of the other members of the laboratory who backed the Complainant’s action.”

This story was supported by the Science Fund for Investigative Reporting.