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At high concentrations (called blooms), the organisms may discolor the water - sometimes red, light or dark green brown or clear.
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In Florida, red tide is caused by microscopic algae (plant-like microorganism) called Karenia brevis or K. brevis. The organism produces a toxin that can affect the central nervous system of fish, birds, mammals and other animals.
Red tides or Harmful Algal Blooms occur worldwide. K. brevis is found almost exclusively in the Gulf of Mexico but has been found on the east coast of Florida and off the coast of North Carolina.
Red tide blooms can last days, weeks or months and can also change daily due to wind conditions. Onshore winds normally bring it near the shore and offshore winds drive it out to sea.
A red tide bloom needs biology (the organisms), chemistry (natural or man-made nutrients for growth), and physics (concentrating and transport mechanisms). No one factor causes it. Tests are being conducted to see if coastal nutrients enhance or prolong blooms.
Most people can swim in red tide but it can cause skin irritation and burning eyes. If your skin is easily irritated, avoid red tide water. If you experience irritation, get out and thoroughly wash off with fresh water. Swimming near dead fish is not recommended.
Symptoms from breathing red tide toxins are normally coughing, sneezing and teary eyes. These are usually temporary when red tide toxins are in the air. Wearing a particle filter mask may lessen the affects, and using over-the-counter antihistamines may decrease your symptoms. Check the marine forecast. Fewer toxins are in the air when the wind is blowing offshore
People with respiratory problems (like asthma or bronchitis) should avoid red tide areas, especially when winds are blowing toxins onto the shore. If you go to the beach, take your short acting inhaler with you. If you have symptoms, leave the beach and seek air conditioning.
You can call the Aquatic Toxins toll free hotline at 800-222-1222. It is staffed 24/7 by medical professionals. If symptoms are severe, call your local doctor.
Commercial seafood found in restaurants and grocery stores is safe because it comes from red tide free water and is monitored by the government for safety.
Recreational fisherman must be careful: Do not eat mollusks (clams or oysters taken from Florida red tide waters, as they contain toxins that cause a food poisoning called NSP (Neurotoxic Shellfish Poisoning). Finfish caught live and healthy can be eaten if filleted. Use common sense! Harvesting distressed or dead animals is not advised under any circumstances. Edible parts of other animals commonly called shellfish (crabs, shrimp and lobsters), are not affected by the red tide organisms and can be eaten. Do not eat the tamale (green stuff, hepatopancreas).
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