General Information

Event name: US-00-004
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: Do not know upper limit but <20 MU to >34.99 MU. Brevetoxins were also detected at low levels in dea)
Associated syndrome: NSP
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: Yes (Florida Fish & Wildlife Conservation Commission's Florida Marine Research Institute, Mote Marine Lab)
Event occurred before in this location: Yes (Florida red tides caused by Karenia brevis (=Gymnodinium breve) have occurred off Florida for hundreds of years. During the last several years they have occurred off the central west coast as well as the northwest coast and to a lesser degree off the northeast coast and the Florida Keys. The highest frequency of occurrence has been between Tarpon Springs and Charlotte Harbor, with the second highest between Tarpon Springs and Pensacola.)
Individuals to contact: STEIDINGER, Karen A.

Location & Date

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Location: Latitude: 27.392778, Longitude: -82.325000
General location information: Gulf of Mexico., SW Florida.
HAB Area code(s): US-16
Additional location information: 1)SW Florida. 27.3930 smf -82.3250 to 24.5276 and -82.0174, winter-spring. 2)SW Florida, 27.7717 and 83.3250 to 24.6917 and -81.7917, summer-winter. 3)NW Florida, ca. 30.3865 and -86.5121, winter. 4)NW Florida, 29.7982 and -85.3050 to 30.3824 and -86.8813, summer-winter.
Bloom event dates (yyyy/mm/dd):
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information: DETECTION DATE: 1)from 1999 to 4/26/00. 2) 9/24/00 to 12/12/00 and then picked up in 2001 in the same area off the Florida Keys. 3) from 1999 to 1/12/00. 4)8/31/00 to 11/29/00. FINAL DATE: See column to left. In the winter of 2000/2001 there were extended open water blooms offshore of the Florida Keys in the Gulf. Blooms offshore are not always detected because of the expanse of area.


Causative organism known: Yes
Causative Species/Genus: Karenia brevis (19.9 milli cells/L)
New genus created by Drs. G. Hansen and Moestrup in Daugbjerg, N., G. Hansen, J. Larsen and O. Moestrup. 2000. Phycologia 39(4): 302-317. G. breve and G. mikimotoi were both transferred to the new genus.
Co-Ocurring Species/Genus: Karenia mikimotoi (13.6 milli cells/L)
Chlorophyll concentration, if known: Chlorophyll data are available for cruises an µg/l
Additional bloom information: K. mikimotoi and other gymnodinioids closely related to K. brevis and K. mikimotoi, one of which produces brevetoxins. Morphologically different from K. brevis but similar to new New Zealand species being described.
Event-related bibliography: Daily status of all K. brevis events during active blooms are posted at . In addition, an electronic database is being developed for 1957 to 1998 and will be updated periodically and placed on the web. 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): Wind velocity:
Temperature (°C): Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: Current Velocity: 0
Nutrient information:
Temperature Range During Event: Max: °C, Min: °C
Salinity Range During Event:
Bloom location in the water column: Whole column
Growth: Advected
In situ
Growth Comments Blooms start offshore the coast and can be transported in with winds, currents; they can move alongshore and cross-shelf and inoculate other areas. They may die out inshore and remain offshore. Once advected populations are inshore there is in situ growt
Additional Environmental information: Too many data points; recent cruise and transect data will start to be available at NODC after July 1, 2001 from a NOAA/EPA funded program called ECOHAB: Florida. Some summary data will be available at web sites. Historical data from 1957 to 1998 will als

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Crassostrea virginica Brevetoxins 34.99 MU Bioassay-Mouse
Crassostrea virginica Brevetoxins < 20 MU Bioassay-Mouse
Kit used: Type of kit used:
Additional information: 12/21/00 Crassostrea virginica. 34.99 MU/100 g. 1/31/00 Crassostrea virginica. <20 MU/100g. Mouse bioassays are conducted after the bloom has dissipated, so after 3 to 6 weeks results should be <20 MU/100 g of shellfish meats because most of the shellfish can purge toxins in that time. In addition to the Mouse Bioassay for shellfish meats, receptor binding assays were run on some water samples . PbTx 3 eq. in ug/L ranged from
Economic losses: Not Determined
Management decision: Shellfish growing areas are closed when K. brevis cell concentrations exceed 5,000 cells/Liter. They are opened when shellfish in a red tide closed area test <20 MU/100 g.
Additional harmful effect information: No NSP cases in humans reported during this event.
Updated at 06:56 on 28 Jul 2020