General Information

Event name: US-98-002
Nature of the harmful event:
Seafood toxins
Event directly affected:
Toxicity detected: Yes
Associated syndrome:
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: Yes
Event occurred before in this location: Yes (Spatial and temporal occurrence patterns repeated every year since 1990 in Mississippi River plume, since 1993 in Terrebonne Bay estuary.)
Individuals to contact: DORTCH, Quay

Location & Date

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Location: Latitude: , Longitude:
General location information: Plume of the Mississippi ., Lousiana.
HAB Area code(s): US-17
Additional location information: All shelf and estuarine waters examined to date. The highest numbers of Pseudo-nitzschia spp. (10,000,000 cells/L) and the highest frequency of occurrence are observed on the shelf in the plume of the Mississippi River. Forth the first time in 1997, we sampled approximately monthly many shallow Louisiana estuaries over oyster beds. Maximum abundances were 1,000,000 cells/L and, depending on the estuary, between 8 and 36% of samples contained Pseudo-nitzschia spp.
Bloom event dates (yyyy/mm/dd):
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information: They occur all year in all locations, although highest abundances seem to be fall through spring.


Causative organism known: Yes
Causative Species/Genus: Pseudo-nitzschia sp. ( cells/L)
Pseudo-nitzschia cf. Americana
Pseudo-nitzschia subfraudulenta ( cells/L)
Pseudo-nitzschia pungens ( cells/L)
Pseudo-nitzschia pseudodelicatissima ( cells/L)
Pseudo-nitzschia delicatissima ( cells/L)
Pseudo-nitzschia multiseries ( cells/L)
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information: Several unidentified species were also found. We have determined from field data (up to 5 pg domoic acid/cell; Parsosns et al. submitted) and clonal culture studies (Doucette, pers. communication) that P. pseudodelicatissima is more toxic than observed pr
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: 30 °C, Min: 9 °C
Salinity Range During Event: Max: 36, Min: 2
Bloom location in the water column:
In situ
Growth Comments
Additional Environmental information: Eutrophic, shallow estuaries and the highly eutrophic plume of the Mississippi River, often highly turbid, high nutrient inputs.

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
Additional harmful effect information: Domoic acid measurements for 1997 and part of 1998 indicate cellular contents of up to 25 pg/Pseudo-nitzschia cell in phytoplankton over oyster beds, especially in the spring. So far there have been no reported cases of human illness or other animal morta
Updated at 03:56 on 9 May 2018