General Information

Event name: US-11-025
Nature of the harmful event:
Water Discoloration , High Phyto concentration , Seafood toxins , Mass mortalities
Event directly affected:
Natural Fish , Birds , Shellfish , Aquatic Mammals
Toxicity detected: Yes (Approximate range: 33.3 g/100 g shellfish)
Associated syndrome: NSP , Aerosolized toxins effects
Unexplained toxicity: No
Species implicated in toxin transmission (transvector): Shellfish
Report the outcome of a monitoring programme: Yes (Fish and Wildlife Research Institute HAB Monitoring Program: Event Response)
Event occurred before in this location: Yes (Historically Karenia brevis blooms occur in SW Florida Shelf (Gulf of Mexico) almost annually; usually beginning in the summer or fall)
Individuals to contact: SCOTT, Paula

Location & Date

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Location: Latitude: , Longitude:
General location information: SW Florida (Sarasota, Charlotte, Lee, Collier & Monroe counties), West Florida
HAB Area code(s): US-16
Additional location information: Gulf of Mexico: 201 miles N to S; 35 miles W to E (patchy movement alongshore throughout the fall, mostly lingering around Lee and Collier counties)
Bloom event dates (yyyy/mm/dd): Event Date:2011-09-26
Start: 2011-09-26,
Quarantine levels dates (yyyy/mm/dd): First detection: 2011-09-26,
Additional date-related information: event ongoing through 2011.


Causative organism known: Yes
Causative Species/Genus: Karenia brevis (30,448,000 cells/L)
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: 35 µg/l
Additional bloom information: coccolithophorid co-occuring - 1,616,000 cells / L
Event-related bibliography: Foley, A., Stacy, B. A., Schueller, P., Flewelling, L. J., Schroeder, B., Minch, K., Fauquier, D. A., Foote, J. J., Manire, C., Atwood, K. E., Granholm, A. A., Landsberg, J. H., 2019. Assessing Karenia brevis red tide as a mortality factor of sea turtles in Florida. Dis. Aquat. Org. 132, 109124.

Environmental Conditions

Weather: Turbidity (NTU): Wind direction:
Stratified water: No Oxygen content (nL/L): 8.8 (mg/L) Wind velocity:
Temperature (°C): 24.6 Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: 34.66 Current Velocity:
Nutrient information:
Temperature Range During Event: Max: 30.6 °C, Min: 16 °C
Salinity Range During Event: Max: 38, Min: 17.2
Bloom location in the water column: Whole column
Growth: Advected
In situ
Growth Comments
Additional Environmental information:

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
clams and oysters Brevetoxins 33.31 MU/100 g Bioassay-Mouse
Kit used: No Type of kit used:
Additional information:
Economic losses: unknown
Management decision: Shellfish harvesting area closures until Karenia brevis cell counts fell below 5,000 cells/L and shellfish NSP fell below 20 MU/100 grams
Additional harmful effect information:
Updated at 08:10 on 29 Jul 2020
Checked at 04:20 on 15 Apr 2015