'Gumbo' of blue-green algae stinks up Manatee and Sarasota beaches

The cyanobacteria isn't toxic to sea life the way Red Tide is, but it smells bad and can cause rashes.
Published May 15
Updated May 15

Last year, when a persistent Red Tide algae bloom touched all three of Florida's coasts, Southwest Florida had to put up with it the longest. The toxic algae stuck around Lee, Charlotte, Sarasota and Manatee county beaches for months on end, driving away tourists and depositing dead fish galore on the shore.

Now a new algae bloom is threatening some of those same beaches. It's not Red Tide. It's a type of blue-green algae known as "Lyngbya," which has long caused problems in the state's springs.

It might give swimmers a rash, but it doesn't kill anything but your appetite.

"It makes you want to go inside and close your windows and turn on your air conditioning, because it stinks," Holmes Beach Mayor Judy Titsworth, granddaughter of the city’s namesake, John “Jack” Holmes Sr., said this week.

While scientists at the state Department of Environmental Protection call it "filamentous cyanobacteria," Titsworth said longtime island residents just refer to it as "gumbo." She said the algae is a recurring problem along the island's beaches.

"This is something we get every few years," she said Tuesday. "Usually it's very little, but every once in a while we get a pretty big bloom. This year we've got a pretty big bloom." Nothing can get rid of it other than a change in the winds or the tide, she said.

The stench it produces is part of a natural process, state agency spokeswoman Mara Gambineri said.

"Blooms of filamentous cyanobacteria can form brownish floating blobs or mats that begin to decay and emit a foul, rotten egg odor caused by the production of hydrogen sulfide gas and other organic breakdown byproducts," she said.

State scientists collected multiple water samples last week from Sarasota and Osprey in Sarasota County, as well as near Anna Maria Island and other locations in Manatee County, she said. Because the mats of algae do not pose the same toxic threat as Red Tide, she downplayed the importance of the findings: "The growth of filamentous cyanobacteria typically increases in the spring and summer months when water temperatures and daylight hours increase."

In the early 2000s, outbreaks of Lyngbya began to plague such Florida tourist attractions as Ichetucknee Springs and Wakulla Springs in North Florida, causing rashes among swimmers. That was a freshwater strain of the algae known as Lyngbya wollei, which grows in dense mats at the bottoms of some lakes and spring-fed systems. These mats produce gases that can cause the mats to rise to the surface, where winds pile them against shorelines.

A 2000 state study of Kings Bay in Citrus County found that Lyngbya had already spread to the point that it "dominated areas of Kings Bay causing habitat destruction, navigation and recreational use impairment and odor problems." Residents frequently rake up the algae mats to dispose of them, but so far they have repeatedly come back, fueled by pollution in the water.

That algae's saltwater cousin, Lyngbya majuscula, grows on estuary or sea bottom. That's what Titsworth observed about her "gumbo" algae.

"When the water was really clear, you could see it clinging to the sea grass at the bottom," she said. "Then it releases from that and floats to the top. Eventually it sinks back down again and decays."

She said the blooms occurred after the spring tourism season ended, so it hasn't affected the local economy the way Red Tide did. But she said she was disappointed that it showed up at all: "It's too bad because the water was so clear and clean, and now it's all dirty and ugly."

Contact Craig Pittman at craig@tampabay.com. Follow @craigtimes.

 

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