Explainer: What is red tide and its impacts?

With reports of possible red tide impacting parts of the Big Bend coast since the weekend, Meteorologist Charles Roop goes over what red tide is.
Published: Oct. 4, 2021 at 7:23 PM EDT|Updated: Oct. 4, 2021 at 8:39 PM EDT
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TALLAHASSEE, Fla. (WCTV) - David Zierden recognized an odor during a weekend trip to St. George Island that wasn’t pleasant.

“We all noticed the tell-tale irritation of the throat, nose and eyes,” he said. “Even the dog started sneezing uncontrollably.”

A native of Panama City, Zierden knew that red tide likely made a trip to the Franklin County coastline. The next morning, he saw dead fish on the beach “as far as you can see.”

Red tide is an algal bloom - with the Karenia Brevis organism being the common one in the Sunshine State - that gets out of control. Red tide gets the name because of the color it displays, though these blooms can also appear green or brown. These blooms are fairly common in Florida, especially in South Florida.

Red tide was likely first reported as early as the 1500s by Spanish explorers, but the blooms have become more frequent in recent years. Runoff from farming, factories, sewage treatment and other nutrient-rich sources can cause the algae to grow faster.

The blooms can cause environmental hardship on local ecosystems. The harmful algal blooms can kill fish, sea turtles and manatees. The decomposition of marine life can deplete oxygen levels in the water, and lead to additional marine death.

For humans and other animals, inhaling the toxins can cause respiratory problems such as stinging eyes and coughing. For those with existing respiratory problems, they can prompt asthma attacks.

Wind patterns and currents can shift the blooms in the Gulf of Mexico to other locations, and is likely what happened leading up to the previous weekend’s bloom arrival. High pressure at the surface to the north of the Big Bend helped to bring an easterly flow at the surface and likely helped to drive in the bloom into the coast. But, according to research, an entire bloom can last as long as 18 months.

“[O]ne of the chlorophyll patches suspected to be red tide, that was visible offshore of that area in satellite imagery, unfortunately moved onshore along much of Franklin County,” according to a statement from Carly Jones of the FWC’s Fish and Wildlife Research Institute emailed to WCTV Monday morning.

Jones said that they have received reports of blooms along parts of the Big Bend coast with offshore reports as early as Thursday. Testing was requested to volunteers over the weekend, she said, and state partners slated to test the water Monday.

The FWC is asking residents to report red tide and fish kill sightings to the agency either on their reporting page on the web, their mobile app or by calling them at 1-800-636-0511.

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