Red Tide Report (Update)

Red Tide Status Update for September 21, 2018

Weekly Change September 15 to 21

Current Conditions

A bloom of the Florida red tide organism, Karenia brevis, persists in Southwest Florida and extends along ~135 miles of coastline, from northern Pinellas to northern Collier counties, and extends offshore (10 miles or more). A patchy bloom of K. brevis also continues in Northwest Florida. Additional details are provided below.

Over the past week in Southwest Florida, K. brevis concentrations generally decreased in areas of Pinellas, Sarasota, and Charlotte counties and increased in northern Manatee County, parts of Lee County, and northern Collier County. Observations of >1,000,000 K. brevis cells per liter (“high” concentrations) occurred in Pinellas, Manatee, Sarasota, Charlotte, and Lee counties and >15 miles offshore of Sarasota, Lee and Collier counties. In Northwest Florida, K. brevis was observed in Okaloosa, Bay, Gulf, and Pasco counties, with up to “medium” concentrations observed in Gulf County only. Relative to last week, cell counts generally decreased in Bay County.

  • In Southwest Florida over the past week, K. brevis was observed at background to high concentrations in or offshore of Pinellas County, background to high concentrations in or offshore of Manatee County, background to high concentrations in or offshore of Sarasota County, very low to high concentrations in or offshore of Charlotte County, background to high concentrations in or offshore of Lee County, and very low to high concentrations in or offshore of Collier County. For additional information, view the southwest coast report Adobe PDF and map Adobe PDF

  • In Northwest Florida over the past week, K. brevis was observed at very low to low concentrations in or offshore of Okaloosa County, low concentrations in Bay County, background to medium concentrations in Gulf County, and background to very low concentrations in or offshore of Pasco County. For additional information, view the northwest coast report Adobe PDF and map Adobe PDF.

  • Samples collected along the east coast of Florida over the past week did not contain K. brevis. For additional information, view the East Coast report Adobe PDF and map Adobe PDF.

Fish Kills
In Southwest Florida, reports of fish kills were received for multiple locations in and/or offshore of Pinellas, Manatee, Sarasota, Charlotte, and Lee counties and one location offshore of Collier County. In Northwest Florida, reports of fish kills were received for Walton, Bay and Gulf counties. More detailed information is available at

Respiratory Irritation
Respiratory irritation was reported in Southwest Florida (in Pinellas, Manatee, Sarasota, and Lee counties) and in Northwest Florida (in Gulf County). For additional information, view the Southwest Coast report Adobe PDF and Northwest Coast report Adobe PDF.


Forecasts by the USF-FWC Collaboration for Prediction of Red TidesExternal Website for Pinellas to northern Monroe counties predict net southwestern movement of surface waters and net southeastern transport of subsurface waters for most areas over the next three days. Three-day forecasts for Northwest Florida predict net eastern transport of surface waters and northeastern movement of subsurface waters from Escambia to western Gulf counties.

Red Tide Status Map (September 21, 2018)
Statewide Red Tide Counts September 13 through 20, 2018
View a larger map Adobe PDF (September 21, 2018)

To see detailed information on this week's samples, view the current Statewide Google Earth map for September 21, 2018External Website

By using Google Earth, you can zoom in to specific locations and click on stations to see detailed information, including sample date and cell concentration. You must have Google Earth installed on your computer to view this map; the software can be downloaded from the Google Earth websiteExternal Website

Archived status maps can be found in our Flickr gallery.

Latest Red Tide Status Report Available by Phone
Call 866-300-9399 at any time from anywhere in Florida to hear a recording about red tide conditions throughout the state. Callers outside of Florida can dial 727-552-2448. Standard calling charges apply.

Reports are updated on Friday afternoon except during holidays, in which case the report will be released on the closest day. Additional information, if available, is provided on Wednesday afternoon. To receive an e-mail when the current status has been updated, visit our subscription area.

Additional Information
For additional information about red tide and the current red tide bloom, including information on how to report a fish kill or other wildlife effects, consult health authorities about human exposure, or locate other resources, visit our Red Tide-Related Hotlines and Information Sources article.

Blue-Green Algae Bloom Information

Additional information regarding the current status of algal blooms in South Florida is being consolidated and posted on the Florida Department of Environmental Protection’s website:


DescriptionKarenia breviscells/literPossible Effects (K. brevis only)
NOT PRESENT - BACKGROUND background levels of 1,000 cells or less None anticipated
VERY LOW >1,000 to 10,000 Possible respiratory irritation; shellfish harvesting closures > 5,000 cells/L
LOW >10,000 to 100,000 Respiratory irritation, possible fish kills and bloom chlorophyll probably detected by satellites at upper limits
MEDIUM >100,000 to 1,000,000 Respiratory irritation and probable fish kills
HIGH >1,000,000

As above plus discoloration


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