ST. PETERSBURG — Now that Red Tide has reached Pinellas County's popular beaches, chasing away tourists and depositing tons of dead marine life, the big question is when it will end.
The short, unsatisfying answer, 10 months after the current bloom cropped up off the Southwest Florida coast, is no one can predict when it will break apart and float away.
"It's certainly something we'd like to know about," said Vincent Lovko, a scientist at Mote Marine Laboratory in Sarasota.
Humans have little control over when Red Tide stops or starts. But, there are three ways that waterfront hotels, restaurants and property owners could finally get some relief from the noxious fumes, say scientists.
Problem is, none of them are happening now.
The way the current bloom reacted to Tropical Storm Gordon last month offers a clue about the first solution. The storm's winds pushed it away from land for a while, lessening the effects and making people feel like things were getting back to normal.
"Sustained winds can push a bloom offshore, and then that's when it can disappear," said Kate Hubbard, a research scientist with the Florida Fish and Wildlife Institute in St. Petersburg.
But once Gordon moved on, the bloom came back to shore again, Lovko said. So in this case, it didn't work.
The second thing to root for is for the algae bloom to end itself, said Edward J. Phlips, an aquatic sciences professor at the University of Florida.
To keep growing, a Red Tide algae bloom needs a steady flow of nutrients, not unlike a crop that requires repeated fertilization. That's why a Red Tide bloom, which starts up to 40 miles offshore, can be prolonged when it moves inshore and is fueled by leaky septic tanks and sewage systems, as well as fertilizer in stormwater runoff.
But if the bloom reaches a certain density, Phlips said, it could pass the point where there are enough nutrients to keep it going "and then it collapses."
Scientists are doing research now on a similar phenomenon known as "programmed cell death," Hubbard said.
Something happens within the cells of the algae themselves that trips a sequence of events that kills the whole bloom. So far scientists have been unable to pinpoint just what sets off the sequence, but if found, that could be the key to ending blooms like the one going on now.
Finally, algae blooms do have predators.
"Sometimes you have organisms that will graze on and eat algae," said Phlips.
The predators include shellfish, which filter the water as it flows through; zooplankton, the tiny animals at the base of the ocean's food chain; and even, in some cases, a fungus. However, Hubbard said, no one has confirmed that fungi feed on the type of algae in Red Tide.
The current outbreak has been particularly unusual, making a forecast on when it will end even harder.
Normally, a Red Tide bloom begins in the late summer or early fall and lasts through the winter until February or March, when it dissipates on its own, Lovko said.
But the current Red Tide, first detected last November, has persisted far beyond when a normal one would sputter out, he said.
Scientists have labeled it the worst in a decade as it's stretched across 125 miles of coastline and, this past week, even showed up off the Panhandle. It's grown more intense over the summer. Its toxins are suspected of killing hundreds of sea turtles, as well as scores of manatees and dolphins.
Because Red Tide routinely lasts through the winter, the traditional Florida lore that says cold water can make Red Tide go away is clearly untrue.
A drop in the temperature of the Gulf of Mexico would have no effect on the continued growth of the algae, according to Hubbard, the Fish and Wildlife Institute scientist.
"They can occur across a whole range of temperatures," Hubbard said.
Rather than wait on an uncertain natural process to kill the Red Tide bloom, Mote has been working on a mechanical device that could strain Red Tide out of the water.
The Sarasota-based lab has been running a test on the device in Boca Grande, according to Mote spokeswoman Hayley Rutger.
"It works like a water purifier," Rutger said. So far, she said, it appears to work — but only in a small waterway such as a canal.
In the meantime, other scientists continue studying the long, long Red Tide bloom and trying to figure out how it will end. At this point, though, Hubbard said, "there's no way to predict when that will be."
Contact Craig Pittman at email@example.com. Follow @craigtimes