General Information

Event name: US-96-005
Nature of the harmful event:
Water Discoloration , Mass mortalities
Event directly affected:
Birds , Aquatic Mammals , Humans
Toxicity detected: Yes (Approximate range: 3,060 g/100 g (84 MU) Brevetoxin.)
Associated syndrome: NSP , Aerosolized toxins effects
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: MONCREIFF, Cynthia A.

Location & Date

[View larger map]
Location: Latitude: , Longitude:
General location information: Hancock, Harrison, and Jackson Counties., Mississippi.
HAB Area code(s): US-17
Additional location information:
Bloom event dates (yyyy/mm/dd): Start: 1996-10-26, End: 1996-12-11
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information:


Causative organism known: Yes
Causative Species/Genus: Gymnodinium breve (630,000 cells/L)
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information: Inshore waters in the immediate vicinity of routinely harvested oyster reefs had cell concentrations ranging from zero to greater than 630,000 cells/L; water samples from the vicinity of the barrier islands had cell counts ranging from negative to in exce
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: 27 °C, Min: 12 °C
Salinity Range During Event: Max: 30, Min: 5
Bloom location in the water column:
Growth: Advected
Growth Comments Advected population from Gulf of Mexico waters in vicinity of Mississippi's barrier islands and the Chandeleur Island chain in eastern Louisiana. Some in situ growth may have occurred in Middle Bay (east Jackson County) and in the vicinity of Cat Island (
Additional Environmental information: Occurred in vicinity of barrier islands and in nearshore waters.

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Kit used: Type of kit used:
Additional information: Presence of brevetoxin confirmed in 6 specimens of lesser scaup sent in for necropsy.
Economic losses:
Management decision: Shellfish harves bans due to Gymnodinium breve red tide in Middle Bay and Mississippi Sound (Area 8) of Jackson County from 2 November 1996 to 25 February 1997; western Mississippi Sound in Hancock County (Area 2) closed from 7 November 1996 to 26 Februar
Additional harmful effect information:
Updated at 03:08 on 14 May 2018