It has killed millions of fish and hundreds of dolphins and manatees. It has ruined countless Florida beach vacations. And it has left people with respiratory problems gasping for air.
Yet until now, how Red Tide's poisons worked remained something of a mystery.
On Thursday, though, 22 investigators from eight agencies meeting at Mote Marine Laboratory in Sarasota unveiled the results of the biggest study ever of Florida's notoriously toxic algae.
The $15-million, decade-long study looked primarily at the human health effects rather than what causes Red Tide blooms. It found that the algae, known as Karenia brevis, contains at least 12 different toxins that can be harmful to humans.
On windy days during a Red Tide bloom, the toxins can be blown up to a mile inland. People with asthma and other respiratory ailments who inhale the toxins suffer more, and longer, than people who don't suffer from breathing problems. One hour of exposure can cause up to five hours of asthma attacks, the study found.
Remarkably, the research found that Red Tide also contains three antitoxins that could provide beneficial effects to humans.
One of these antitoxins is now being used to develop a new drug called Brevenal that can be used to treat cystic fibrosis and that appears to be considerably more effective than current cystic fibrosis treatments. It can be used to treat other ailments too, such as chronic obstructive pulmonary disease. The researchers are now seeking a pharmaceutical company to manufacture the drug.
"It's cool, isn't it?" asked Barbara Kirkpatrick, a Mote Marine senior scientist who led the fieldwork for the study. "That's the beauty of research. You never know where it's going to take you."
Red Tide has plagued Florida's beaches for centuries. Spanish explorers recorded blooms in the 1500s. Karenia brevis — named for retired biologist Karen Steidinger, who spent decades studying its properties at the state's marine science laboratory in St. Petersburg — lives in the Gulf of Mexico all year long, usually without causing anyone any problems.
But every now and then the algae population just offshore explodes into something called a bloom, staining the water a rust color and releasing large amounts of toxins. No one knows what spurs those blooms or how to stop them, but they can wreak havoc with the state's fishing and tourism industries.
In 1971, for instance, a Red Tide bloom stretched from the Sunshine Skyway bridge up into Old Tampa Bay, leaving thousands of dead fish in St. Petersburg's canals and bayous. A 1996 bloom along the Southwest Florida coast killed 158 manatees that had inhaled the toxins.
The National Institute of Environmental and Health Sciences agreed to put up the money for the study after years of questions and complaints about what effect Red Tide might be having on Floridians and tourists who get caught at the beach during a Red Tide bloom.
Investigators from all over the country helped, including from the Centers for Disease Control and Prevention and the Cincinnati Children's Hospital Medical Center.
As a result, "we learned more during this study than scientists had been able to uncover in the past 150 years," said Daniel Baden, director of the Center for Marine Science at the University of North Carolina Wilmington, who led the Red Tide study.
More than 500 residents volunteered to help out the studies. Some were people with chronic lung conditions. Some residents let researchers place air sampling devices in their driveways.
However, toward the end the study was hampered by an unusual problem, Kirkpatrick said. Since 2009, there have been no major Red Tide blooms off the Florida coast. But by then the investigators had gathered enough material to keep working on lab tests, she said.
A bigger hurdle might hamper any efforts at further Red Tide research, Baden said.
"We would not be able to do this study in the current climate in Congress," he said, noting measures that cut the funding for research paid for by the NIEHS.
Craig Pittman can be reached at firstname.lastname@example.org.