What Is Red Tide – And Is It Safe to Swim in It?

The infamous Florida red tide is actually an algal bloom, which is a higher-than-normal concentration of a certain type of microscopic alga (a plant-like organism). In the Gulf of Mexico, the species responsible for most red tides is Karenia brevis, also known as K. brevis. Because K. brevis cannot tolerate low-salinity waters for very long, blooms usually remain confined to salty coastal waters. If the concentration becomes high enough, a red tide can actually cause the water to take on a telltale reddish hue.

Red tides can last anywhere from a few weeks to more than a year. The duration of a bloom will depend on many factors that can influence its growth and persistence, such as sunlight, water salinity, and nutrients, as well as the speed and direction of water and wind currents. Scientists have not established a link between pollution and red tide, which usually develops miles offshore, far from manmade nutrient sources that could potentially fuel its growth.

Florida red tides can be harmful because they produce toxic chemicals known as brevetoxins, which can affect the central nervous system of fish, causing the fish to die. Additionally, wave action can break open K. brevis cells, allowing the toxins to be released into the air. In response to exposure, some individuals may experience respiratory irritation that produces coughing, sneezing, tearing, and an itchy throat. This can lead to serious illnesses in people who have chronic or severe respiratory conditions, such as asthma and emphysema, so those individuals are advised to avoid red tide areas.

For most people, swimming in a Florida red tide is safe – as long as there are no dead fish present (dead fish can harbor harmful bacteria). However, red tide toxins can sometimes cause skin irritation and burning eyes, so if any inflammation develops, it’s best to get out of the water and rinse off with fresh water immediately. People who are especially prone to irritation from plant products should avoid swimming in an area affected by a red tide bloom.

If you have questions about the Florida red tide, or you are experiencing lung or skin irritation, you can see a doctor at South Tampa Immediate Care without an appointment. Just stop by our walk-in clinic located on South Howard Avenue in Tampa, FL.