Red Tide, the toxic algae that has plagued Florida's coasts since the days of the Spanish conquistadors, is making a big mess on Pinellas County's beaches this week.
The sewage that was dumped into Tampa Bay could make it even worse.
The first report came in Saturday: dead fish washing up on the beach at the Tradewinds Resort on St. Pete Beach. Since then, thousands of dead fish have created a smelly mess at John's Pass, Redington Beach, Treasure Island and Sunset Beach too, said Kelly Redmond of the state's Fish and Wildlife Research Institute in St. Petersburg, which monitors toxic algae blooms.
The fishkill marks one more environmental woe to plague Florida in 2016.
A thick coating of toxic green algae and its powerful stench ruined the Fourth of July weekend for Stuart businesses and lingered for months afterward. Earlier this month, Hurricane Hermine smashed Tallahassee and knocked out its power while drenching the bay area.
Hermine, along with earlier summer storms, also overwhelmed the sewage treatment plants in St. Petersburg, Gulfport and other Pinellas cities, leading them to dump millions of gallons of sewage into Tampa Bay and Boca Ciega Bay.
The Red Tide algae blooms aren't caused by the release of waste into the coastal waters. But sewage can fuel the bloom so that it sticks around longer.
"Red Tide occurs offshore, but can it use man-made nutrients once it's on shore? Yes, it's capable of that," Redmond said Wednesday. "To what extent, we don't know."
The algae bloom is killing off a lot of different kinds of fish.
"We've got everything," Redmond said. "We've got pinfish, bait fish, sardines, threadfin catfish and eels."
A sea turtle washed ashore on St. Pete Beach earlier this week, but it's unknown at this point if the Red Tide is responsible for killing it.
Pinellas' tourism-based beach businesses have learned to cope with these nearly annual Red Tide outbreaks. This one hasn't been bad, so far.
Some tourists who talked about cutting their stay short changed their minds once they learned city work crews were picking up all the dead fish, said Clyde Smith, the general manager of Bilmar Beach Resort on Treasure Island.
"We saved several (bookings) who were considering moving on," he said.
The toxins produced by Red Tide can cause skin irritations and respiratory trouble, especially for people with asthma. That can really drive the tourists away, Smith said.
"When you walk out of your hotel room and feel like you've been pepper sprayed, then you've got a problem," Smith said. But so far, he said, no one has reported any breathing problems.
As for the dead fish, "for the moment it's just, 'Clean up and keep going,'" said David Downing, executive director of Visit St. Pete/Clearwater, the county's tourism marketing agency. It helps that the fall is a shoulder season. If this lasts through January, though, and into winter tourism season, then it could cause problems.
"We get concerned if it's sustained and severe," Downing said.
Red Tide has stunk up Florida's beaches for centuries. Spanish explorers recorded blooms when they visited in the 1500s.
Small, scattered colonies of the microscopic algae Karenia brevis — named for retired biologist Karen Steidinger, who spent decades studying its properties at the state's marine science lab in St. Petersburg — live in the Gulf of Mexico all year long. Usually they cause no problems.
But every now and then, the algae population offshore explodes into something called a bloom in which the algae multiplies rapidly and spreads. The expanding bloom stains the water a rusty color that gives the creature its name.
No one knows what causes the bloom to begin offshore, and no one knows what causes it to end.
The big blooms release toxins that are deadly to marine creatures. A bloom along the Southwest Florida coast in 2013 killed 200 manatees.
Those blooms can last for months, fueled sometimes by nitrate pollution flowing from overfertilized yards, leaky septic tanks and other sources, including the sewage dumped by cities.
The last such major bloom to hit Pinellas began in September 2015 and lasted through April, Redmond said.
Red Tide and its fish kills began showing up last week on the beaches of Sarasota and Manatee counties, then spread northward, as often happens in late September and early October.
The bloom appears to be patchy at this point, Redmond said, with areas of high concentration of the algae interspersed with areas where there is only a low concentration, stretching along the coast down to the Englewood area south of Sarasota.
Contact Craig Pittman at [email protected] Follow @craigtimes.