General Information

Event name: US-96-007
Nature of the harmful event:
Seafood toxins , Mass mortalities
Event directly affected:
Birds , Aquatic Mammals
Toxicity detected: Yes
Associated syndrome: OTHER
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: Yes
Event occurred before in this location: No
Individuals to contact: DORTCH, Quay

Location & Date

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Location: Latitude: , Longitude:
General location information: , Louisiana.
HAB Area code(s): US-17
Additional location information: Lousiana coastal waters from the Lousina/Mississippi border to 90 40' W.
Bloom event dates (yyyy/mm/dd): Start: 1996-11-12, End: 1996-12-17
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information: But toxicity on-going (as of Mar. 13, 1997).


Causative organism known: Yes
Causative Species/Genus: Gymnodinium breve (5,000 cells/L)
Co-Ocurring Species/Genus: Dinophysis caudata ( cells/L)
Prorocentrum spp. ( cells/L)
Chlorophyll concentration, if known: µg/l
Additional bloom information: Inshore waters east of Mississippi River: Exceeded 5,000 cells/L from Nov. 12, 1996 (start of sampling) to Dec. 4, 1996 with maximum abundance of 620,000 cells/L on 20/11/96. Inshore and shelf waters west of Mississippi River and east of 9040'W. Ovserved
Event-related bibliography:

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:
Growth Comments There is no direct data at present to assess this question, but reported dates when Gymnodinium breve was present in Florida, Alabama, and Mississippi waters suggest advection from east was a factor. Growth must also have occurred to maintain such high nu
Additional Environmental information: Occurred in nearshore and shelf waters between 5 and 34.5 ppt and 14.5 and 21C. Abundances above regulatory limits (>5,000 cells/L) occurred in Lousiana waters betwee 18 and 28 ppt, but data from Mississippi suggests a lower salinity (15 ppt).

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Brevetoxins Bioassay-Mouse
Kit used: No Type of kit used:
Additional information:
Economic losses:
Management decision: Shellfish harvest bans due to Gymnodinium breve from Nov. 13, 1996 to Feb. 28, 1997, Mississippi River Gulf Outlet to the Lousiana/Mississppi River border. Some areas opened Feb. 28, 1997 after 2 consecutive negative toxin tests (mouse bioassay); some are
Additional harmful effect information: