Red Tide FAQ
What is red tide?
Red tide is a higher-than-normal concentration of a microscopic alga (plantlike organism). In Florida and the Gulf of Mexico, the species that causes most red tides is Karenia brevis, often abbreviated as K. brevis.
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 do red tides 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.
Do red tides 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.
Will I experience respiratory irritation during a 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.
Is it safe to swim during a red tide in Florida?
Swimming is safe for most people. However, red tide can cause some people to suffer skin irritation and burning eyes. 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 during a 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.
Where can I get more information about red tide?
For complete information and advisories, please refer to the Florida Fish and Wildlife Conservatin Commission's red tide pages.