ST. PETERSBURG — A Red Tide algae bloom that has plagued Charlotte and Sarasota counties for months recently moved north into Manatee and Pinellas counties.
Now fish kills have begun littering the waters and beaches around Pass-a-Grille, Boca Ciega Bay, the Sunshine Skyway and Terra Ceia Bay, said Kelly Richmond, a spokeswoman for the Florida Fish and Wildlife Research Institute in St. Petersburg.
On Monday, residents of those areas began reporting respiratory problems such as coughing and scratchy throats, she said.
No one knows how long this Red Tide bloom might last, but experts say that once it gets into the bays and estuaries "it does hang on for a while," she said.
Gulfport residents have noticed the dead fish recently and wondered what was happening, said resident Judy Portnoy.
"People were curious because there were quite a few," she said. "We wondered if it was a Red Tide."
Richmond said the reports of fish kills began filtering in to the marine science lab from Pinellas beaches on Nov. 12. So far the bloom has killed mullet, grunt, sheepshead, catfish and spadefish.
The last Pinellas Red Tide bloom to cause fish kills was last year, when a bloom offshore deposited dead fish on Honeymoon Island, Madeira Beach and Clearwater Beach, she 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 it causes 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.
The big blooms release toxins 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.
A bloom off the Panhandle beaches has been going on since September, and so far county officials have hauled off 6 tons of dead fish, Richmond said. Meanwhile the bloom off the Charlotte and Sarasota coasts that began in October has lingered, until wind and currents pushed it northward.
Contact Craig Pittman at firstname.lastname@example.org. Follow @craigtimes.