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FWC: ‘Medium’ levels of red tide algae found at St. George Island

As the FWC confirms medium concentrations of the organism that causes red tide, a NOAA scientist says there is uncertainty on how long the algae bloom will last
Published: Oct. 6, 2021 at 7:02 PM EDT
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TALLAHASSEE, Fla. (WCTV) - The foul smell and dead fish found over the weekend in St. George Island appeared to be red tide as water tests confirmed a medium concentration of the algae in the water.

Data from FWC showed two samples taken Oct. 4 and Oct. 5 on the beach and just offshore that had levels of Karenia Brevis between 100,000 to 1 million cells per liter of sampled water.

Satellite imagery indicated the likelihood of higher concentrations of red tide with an eight-day composite from NOAA that showed the bloom right along the St. George Island coast, and also just off the coast of Steinhatchee. The Mote Lab also had reports of “many” dead fish, and “moderate” respiratory irritation as the algae create the toxin.

“Unfortunately, it always produces a toxin, so if it’s present, there will be toxin, and the more there is, the more toxin there is,” said Rick Stumpf, Ph.D., an oceanographer with NOAA.

The specific algae of concern is the Karenia Brevis organism, and is what produces red tide.

The algae normally hides near the sea floor, Stumpf said, since the water is clearer and can also take in nutrients close to the sea floor. But he said they can still swim up and down in the water to take in sunlight and nutrients to survive. The algae can be also forced upward to the surface by the weather.

“The upwelling is wind patterns that cause wind blowing onshore, drag surface water offshore, and it brings the bottom water up with the organism,” Stumpf said. “And they collect at the shore and concentrate.”

The nutrients that these algae need to populate come from the rivers, the land, and even the air.

“African dust [...] actually sets off some other blooms that fix nitrogen out of the atmosphere,” he said.

Those nutrients come from natural sources, but the release of nitrogen from un-natural sources could be exacerbating the blooms. To tame it, human behaviors have to change.

“We need to reduce the amount of nutrients we have going into coastal waters,” Stumpf said.

He says these blooms tend to develop in the fall, but passing cold fronts help move them south in the Gulf of Mexico and into the Gulf Stream.

But Stumpf said that didn’t happen this past winter and the last bloom in 2018, and he and his team have been looking into whether a changing climate is playing a role in that.

“You normally think of climate change as rain and temperature, but wind patterns may shift also,” he said. “This just could be a random thing that we’ve had these events three years apart but we need to understand whether the wind patterns might be changing to effect the bloom in the summer time.”

A warming of the ocean water, Stumpf said, can cause the stratification of the warmer temperatures at the water surface and cooler water remains below. The lack of mixing of the water would keep Karenia Brevis deeper in the water and produce the toxin that kills aquatic life, which would also deplete oxygen levels to keep the feedback going.

“Heating [of the sea water] can cause an indirect problem,” Stumpf said. “A lot of heating in the Gulf leads to this stratification.”

As for when this current bloom would end, the NOAA oceanographer didn’t have a clear answer.

“[For the Big Bend and Florida Panhandle] blooms, we don’t have a good understanding of their time and duration,” he said. “The best thing I can say is they usually don’t last long.”

“If you get a [cold] front in, it will push it out and it will go out to the middle of the Gulf of Mexico.”

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