At levels of medium and above, the algae is considered to be at bloom strength, and it is more likely to cause harmful impacts to human health and the environment. Wildlife officials determine the severity of the algae by measuring the number of cells of Karenia brevis-the microscopic organism that causes red tide-found in a liter of water. Water samples collected by Florida Fish and Wildlife Conservation Commission and partners last week confirmed red tide's presence. In Manatee County, fish kills and respiratory irritation were reported in Anna Maria, Holmes Beach and Bradenton Beach this week. It is also wrapping around the south end of Pinellas County, where impacts have already begun to hit some beaches. The bloom's presence is also stronger around Anna Maria Island and Tampa Bay, water samples and local reports show. However, historical patterns have confirmed a typical pattern for the blooms, according to Cynthia Heil, director of Mote Marine Laboratory's Red Tide Institute in Sarasota: A red tide usually starts in late summer or fall, lasts five to seven months and ends by spring.Īs the densest part of the current bloom has drifted north in recent days, algae levels have lessened somewhat around Sarasota County, but reports of dead fish and breathing irritation continue to come in from the county's public beaches, including Siesta Key. 'Once it does that, it's off and running, and it's very hard to stop it.'Īs for what causes a bloom to dissipate, scientists still don't have a solid answer. 'By virtue of killing fish, it generates its own nutrient supply,' University of South Florida emeritus oceanography professor Robert Weisberg said in October, when the bloom was just beginning to appear on the radar. Red tide has persisted since October, when elevated levels of algae reached the coast shortly after Hurricane Ian stirred up the Gulf of Mexico.

Red tide florida cause