Earlier this spring, a city-funded study concluded that dozens of pelicans found dead in January had been exposed to botulism while feasting on tilapia carcasses.
But the Florida Fish and Wildlife Conservation Commission said recently that a toxin from Red Tide was found in some of the birds and may have contributed to their deaths.
Wildlife commission officials would not say if the pelican deaths are part of a criminal inquiry into St. Petersburg's sewage-dumping woes, but Red Tide can be caused by sewage spills.
"As the investigation is ongoing, we are unable to speak of any connection that may exist," spokeswoman Kelly Richmond said. The commission is investigating the city's dumping of 200 million gallons of sewage from an overburdened system since August 2015.
A few months ago, interim Water Resources director John Palenchar said the city-sponsored study proved the city's sewage crisis had nothing to do with the dead pelicans.
"This should alleviate all fears that this natural occurrence had anything to do with the discharge of partially treated wastewater over the past two summers," Palenchar said March 3 when the study's preliminary results were released.
But the city's consultants, who were paid $25,587, weren't the only ones investigating the 70 pelican deaths.
Last week, the wildlife commission confirmed some of the 15 pelicans tested had low to moderate levels of a neurotoxin associated with Red Tide.
The presence of the toxin suggested Red Tide "may also have contributed to some of their deaths," according to an agency update in early April.
The city-funded study did mention the Red Tide toxins found in the pelicans and noted that a Red Tide algae bloom was present in lower Tampa Bay when the birds died. Although Red Tide toxins were present in the gastrointestinal contents of some of the pelicans, tissue samples were negative, the report stated.
However, the possibility of a link between Red Tide, sewage and the pelican deaths was never broached in the consultant's report.
Palenchar, the city's sewer chief, has said he is skeptical that the nutrients in the human waste discharged into Tampa Bay in the fall could have contributed to January's Red Tide outbreak.
He concedes that those nutrients can contribute to the formation of Red Tide, and that the city's most recent discharge into Tampa Bay after Hurricane Hermine in September may have "exacerbated" nutrient levels in the bay.
But he doesn't see a strong correlation between the 93 million gallons of partially treated sewage the city dumped into the water about ¼ of a mile east of Albert Whitted Airport and the Red Tide present in the region four months later.
"I'm still pretty confident in what I said: that this wasn't related," Palenchar said Friday.
He said there is much stronger evidence that the botulism outbreak associated with the dead tilapia killed the pelicans. The city's consultant reported that the pelicans died after eating tilapia infected with a rare bacteria produced during a cold snap in a lake next to Riviera Bay.
The wildlife commission's update also noted the botulism, but the agency hasn't reached any final conclusion on the causes of death.
The birds started dying around the time Mayor Rick Kriseman stated two summers of sewage dumps had not damaged Tampa Bay. Kriseman made those comments after he and former Mayor Bill Foster traded barbs after Kriseman's State of the City speech in January. Foster charged that the sewage released under Kriseman's tenure had damaged the bay's environmental health.
When word of pelicans dying spread through social media, the city quickly contacted the wildlife commission and hired the consulting firm, Arcadis, to determine the cause.
Any attempt to tie the pelican deaths to sewage, said Public Works spokesman Bill Logan, is a stretch.
"It's a dotted line with a lot of dots to connect," he said. "It's a ridiculous exercise."
Contact Charlie Frago at email@example.com or (727)893-8459. Follow @CharlieFrago.