Your questions answered on red tide


PALM BEACH COUNTY, Fla. – With its arrival this week in Palm Beach County, the foul smelling, fish killing red tide has now rolled into every coast of Florida this year.

The naturally occurring algae blooms have wreaked havoc on the state's tourism industry and have become a major issue in both Florida's race for governor and U.S. Senate.

But what exactly is red tide? Well, the experts at the Florida Fish and Wildlife Conversation Commission have some answers.

What is a Florida red tide?

A red tide, or harmful algal bloom, is a higher-than-normal concentration of a microscopic alga (plantlike organism). In Florida, the species that caused most red tides is Karenia brevis, or K. brevis. 

Are red tides red?

At high enough concentrations, Florida red tide can discolor water a red or brown hue.

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 Florida 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. 

Where is Florida red tide found?

The Florida red tide can be found in bays and estuaries but not in freshwater systems such as lakes and rivers. K. brevis cannot tolerate low-salinity waters for very long, so blooms usually remain in salty coastal waters.  This summer, Florida’s Gulf Coast was plagued by red tide. Monday, state health officials confirmed the presence of red tide in the waters off Palm Beach county. 

Why are red tides harmful?

Many red tides produce toxic chemicals that can affect both marine organisms and humans. The Florida red tide organism, K. brevis, produces toxins that can affect the central nervous system of fish and other vertebrates, causing these animals to die. 

Source: Florida Fish and Wildlife Conservation Commission