What is red tide?
Red tide is a higher-than-normal concentration of a microscopic alga (plant-like organism). In Florida and the Gulf of Mexico, the species that causes most red tide is Karenia brevis, often abbreviated as K. brevis. You may hear it referred to as red tide, red tides, or a red tide bloom.
When is red tide present at Florida beaches?
Red tide is more common in the warmer summer and fall months, but it can occur at other times of year.
It's important to know that red tide is sporadic, not ever-present. In other words, there's a very good chance you won't have to worry about red tide during your beach vacation in St. Pete/Clearwater, Florida.
If there is red tide at one beach in St. Pete/Clearwater, does that mean all area beaches will be affected?
Not necessarily. Due to variations in wind and currents, red tide may be present at some area beaches and not at others, or the intensity may vary.
How can I find out if specific beaches are affected by red tide in St. Pete/Clearwater?
You can check our Beach Updates & Conditions page. If red tide is present in any significant way, details on area beaches will be posted there.
Mote Marine Laboratory & Aquarium also monitors red tide along the Gulf Coast of Florida. You can find Mote's Beach Conditions Report here.
Florida Fish & Wildlife Conservation Commission has a red tide status page. You can also call 866-300-9399 (from within Florida) or 727-502-4956 (from outside Florida) to hear a recording about red tide conditions throughout Florida.
What happens when red tide is present?
If red tide is present, there may be fish kill on area beaches. There may be an odor that is unpleasant, and some people may experience respiratory irritation.
Will I experience respiratory irritation when there is red tide in Florida?
Some people experience respiratory irritation (coughing, sneezing, tearing and an itchy throat) when the red tide organism, Karenia brevis, is present and winds blow onshore. Offshore winds usually keep respiratory effects experienced by those on the shore to a minimum. The Florida Department of Health advises people with severe or chronic respiratory conditions, such as emphysema or asthma, to avoid red tide areas.
Find more information forecasting respiratory irritation here. This experimental tool tries to predict where the air may cause irritation based on wind and ocean current forecasts.
Is it safe to swim when there is red tide in Florida?
Swimming is safe for most people. However, red tide can cause some people to suffer skin or eye irritation. People with respiratory illness may also experience respiratory irritation in the water. Use common sense. If you are particularly susceptible to irritation from plant products, avoid an area with a red tide bloom. If you experience irritation, get out of the water and thoroughly wash off.
Is it OK to eat shellfish at a restaurant or purchase shellfish from a seafood market when there is red tide?
Store-bought and restaurant-served shellfish are safe to eat during a bloom because the shellfish are monitored by the government for safety. Commercially available shellfish are often not locally harvested and, if harvested locally, are tested for red tide toxins before they are sold.
Is red tide a new phenomenon?
No, red tides were documented in the southern Gulf of Mexico as far back as the 1700s and along Florida's Gulf coast in the 1840s.
How long does red tide last?
Red tides can last as little as a few weeks or longer than a year. They can even subside and then reoccur. The duration of a bloom in nearshore Florida waters depends on physical and biological conditions that influence its growth and persistence, including sunlight, nutrients and salinity, as well as the speed and direction of wind and water currents.
Does red tide occur anywhere else?
Yes, many algae species cause red tides all over the world. However, the organism that causes Florida's red tide, Karenia brevis, is found almost exclusively in the Gulf of Mexico and occurs from Mexico to Florida. K. brevis can be transported around the Gulf of Mexico as coastal waters move with winds and currents. Some red tides have even been carried by the Gulf Stream current into the Atlantic Ocean as far north as Delaware.
Where can I get more information about red tide?
For complete information and advisories, please refer to the Florida Fish and Wildlife Conservation Commission's red tide page.