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´Tis the Red Tide season; high levels in the Panhandle coast

It is not a bad start to the Red Tide season across western Florida, especially since no microorganisms have been detected in the southwest, where toxic algae blooms often occur during early fall. But there are high concentrations along the Panhandle's coast, especially in Bay and Gulf counties, affecting St. Andrews Bay and Mexico Beach. Here, Authorities have warned beachgoers to stay off the water to avoid skin, eye, and respiratory problems. They also advise against eating shellfish, as they may have become contaminated and be lethal; there have been fish kills in some areas.

Statewide Red Tide Status Map (October 31, 2025) by Fish and Wildlife Conservation Commission

The red tide is a harmful algal bloom caused by the naturally occurring alga Karenia brevis (K. brevis). When K. brevis appears in large quantities – typically in the Gulf of Mexico – it can turn ocean water red, brown, or green.

FWC
Karenia brevis (light micrograph) Karenia brevis is a single-cell organism belonging to a group of algae called dinoflagellates. Karenia brevis is known as the Florida Red Tide organism. In large numbers, it causes red tide along Florida’s coastline. Karenia brevis can be found in Gulf waters any time of the year, but most commonly in the fall.

When this bacteria is present in the water, its contaminants deplete the oxygen, making it a fatal environment for in-water and waterfront residents and visitors. Red tides can have debilitating effects on marine life. If the microorganisms are concentrated at over a 10,000-cell-per-liter rate, fish of all kinds can start dying.

The toxic algae start building at microscopic scales well offshore. Warm waters and nutrients feed these microorganisms, and they often grow to high concentrations in the spring and summer months. The winds and currents drive the micro-organisms to the coast, and when they form large blooms, the winds and currents can carry them for miles along the coast. While Red Tide occurs almost every year, its severity varies.

Red Tide is also not limited to ocean waters. The toxic bloom has sometimes grown in canals, the Intracoastal, and other waterways. If the conditions allow the microorganism to survive and thrive, it will grow and affect the water and the surroundings.


Red Tide is not new to Florida. A prolonged Red Tide event in 2018 lasted over 10 months. During this period, the Red Tide was severe, killing thousands of fish, stingrays, manatees, dolphins, and turtles. Once these toxins occur, there is not much we can do about them, at least in the short term.

It impacts humans and nearby businesses, too.

Although not recommended, most people can safely swim in Red Tide. However, it can cause skin irritation and burning eyes. Inhaling the toxins can lead to coughing, sneezing, and teary eyes, though those symptoms are typically temporary. People with chronic respiratory conditions, such as asthma, are advised to avoid Red Tide. While the medical effects on humans generally aren't serious, Red Tide is affecting the local economy in Florida: some small businesses have temporarily closed in recent years. In seasons when algal blooms have been extensive in both distance and duration, many tourists have either changed destinations or canceled plans to visit the west coast of Florida.

Warmer, drier-than-usual conditions prevail across Florida during La Niña winters.

La Niña and Red Tide

La Niña is present, bringing warmer-than-normal temperatures to Florida and its surroundings. Limiting the use of harmful fertilizers across the state, even in inland areas, could also help curb the growth of toxic algae. More nutrients and runoff can make these harmful algae blooms grow faster and more prominent.

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