General Information

Event name: US-98-001
Nature of the harmful event:
Water Discoloration , Mass mortalities
Event directly affected:
Planktonic life
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: Yes (Several; first documented in August-September 1979 (Perry et al. 1979. First record of a bloom of Gonyaulax monilata in coastal waters of Mississippi, Gulf Research Reports 6 (3): 313-316; also reported during summer of 1986.)
Individuals to contact: MONCREIFF, Cynthia A.

Location & Date

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Location: Latitude: , Longitude:
General location information: Harrison and Jackson Counties., Mississippi.
HAB Area code(s): US-17
Additional location information:
Bloom event dates (yyyy/mm/dd): Start: 1998-08-28, End: 1998-09-25
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information:


Causative organism known: Yes
Causative Species/Genus: Alexandrium monilatum (>16,000,00 cells/L)
surface water, vicinity of the barrier islands
Alexandrium monilatum (48,000 - 3 cells/L)
Inshore waters
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information:
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: 31 °C, Min: 26 °C
Salinity Range During Event: Max: 32, Min: 15
Bloom location in the water column:
Growth: Advected
In situ
Growth Comments Advected population from northern Gulf of Mexico waters south of Horn Island, one Mississippi's barrier islands. Extensive in situ growth in the south half of the central and eastern segments of Mississippi Sound.
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:
Economic losses:
Management decision: None. Booms appeared to be dispersed by Hurricanes George.
Additional harmful effect information: Water discoloration; moderate plankton mortalities in Mississippi Sound within blooms; not uniformly distributed.
Updated at 06:23 on 17 Mar 2020