SARASOTA, Fla. — Red tide is an unusually persistent harmful algal bloom in our water caused by Karenia brevis, a type of algae that produces potent neurotoxins.
It can be deadly to sea life. The toxins can also be suspended in the air near beaches and cause human respiratory illness.
The Florida Fish and Wildlife Conservation Commission (FWC) reported Wednesday that low levels of red tide have now been measured as far north as Sarasota County (Turtle Beach).
FWC has measured high levels at times around Ft. Myers to Naples since December 2020, which has included fish kills and odor along some of the beaches. High levels of red tide were reported today by FWC, just west of North Captiva Island in Lee County.


No one who lived around Tampa Bay in 2017-18 will forget the historic red tide event that killed fish, sea turtles, manatees, birds and dolphins. It kept people from the beaches and hurt local businesses as well.
The worst part of that red tide event lasted 15 months from November 2017 until January 2019.
FWC tells 10 Tampa Bay that they have no way of predicting red tide very far into the future, or how far or if it will move from current locations, as it depends on weather and currents.
NOAA says that red tides in Florida can last as little as a few weeks or longer than a year. In 2005, for example, a bloom started off the coast of St. Petersburg in January and then spread from there to Pensacola and Naples by October, persisting for the majority of the year.
The duration of a bloom 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.
So far, FWC says that samples from Pinellas and Manatee counties have not contained red tide.
You can check daily red tide numbers across the state here.
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