aerial view of red tide bloom

HAB Researchers Continue to Track Red Tides in FL

by Alina Corcoran


fish kill

aerial view of red tide bloom
Fish kill in St. Joe Bay during September (top, image courtesy of A. Reich) and aerial image of K. brevis bloom off Venice during December (bottom, image courtesy of T. Reinhart).

In September, a Florida resident reported that she and her family experienced respiratory irritation in Northwest Florida at Bid-A-Wee Beach in Panama City. At the same time, FWC’s Harmful Algal Bloom (HAB) group confirmed that bloom concentrations of Karenia brevis were present in water samples collected by the Florida Department of Agriculture and Consumer Services (FDACS) and volunteers for the HAB program from Gulf and Franklin counties. Sampling efforts, along with reports of respiratory irritation and fish mortalities throughout October, demonstrated the persistence of K. brevis blooms in this area, with expansion of the bloom west towards Okaloosa and Walton counties by the end of October. In early November, the FWC Fish Kill Hotline received reports of fish and crab mortalities in Manatee and Charlotte counties in
Southwest Florida, which were quickly linked to red tide — confirming the presence of co-occurring blooms in both Northwest and Southwest Florida.

Since late September, the HAB group has been tracking these blooms through sample analysis as well as imagery supplied by USF’s Optical Oceanography Laboratory.  Multiple FWC partners, including staff in the Fisheries Independent Monitoring, Fisheries Dependent Monitoring, Mollusc, and Fish and Wildlife Health groups, have contributed to sampling efforts. Sample analysis has also ramped up, thanks to teamwork by multiple HAB staff! FWC HAB staff have continued to work with USF researchers to generate short term forecasts of bloom movement via the Collaboration for Prediction of Red Tides.

Sampling this year — markedly skewed towards inshore waters — has revealed persistent blooms in bays and estuaries including Pensacola Bay, St. Andrews Bay, St. Joe’s Bay, Tampa Bay, Sarasota Bay, and Charlotte Harbor. Tidal cycles have pushed K. brevis into Tampa Bay past the Skyway Bridge, where staff recently confirmed concentrations greater than 3 million cells L-1. The blooms in both regions have resulted in numerous fish kills, extensive respiratory irritation, and multiple closures of shellfish harvesting areas.
The FWC HAB group publishes a midweek red tide update each Wednesday and a full report each Friday by 5pm on the FWC website at:

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