General Information

Event name: US-91-001
Nature of the harmful event:
Seafood toxins
Event directly affected:
Toxicity detected: Yes (Approximate range: 120 g STXeq / 100 g)
Associated syndrome: PSP
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: Yes
Event occurred before in this location: Yes (Annual event since 1972, usually in May/June.)
Individuals to contact: WHITE, Alan

Location & Date

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Location: Latitude: , Longitude:
General location information: Massachusetts and Georges Bank., Massachusetts.
HAB Area code(s): US-04 US-06
Additional location information: Northern coast of Massachusetts (area 4), Georges Bank (offshore, area 6).
Bloom event dates (yyyy/mm/dd):
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information: June - July.


Causative organism known: Yes
Causative Species/Genus: Alexandrium tamarense ( cells/L)
Alexandrium fundyense ( cells/L)
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information: Alexandrium fundyense and/or A. tamarense (variety not determined).
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: Advected
Growth Comments Advection from the North is the most likely cause of toxicity. The cause of the offshore toxicity and its linkage with inshore toxicity remains to be clarified.
Additional Environmental information:

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Spisula solidissima Saxitoxins STX eq Bioassay-Mouse
Mya arenaria Saxitoxins STX eq 120 Bioassay-Mouse
Kit used: Type of kit used:
Additional information: Low toxicity levels; reached only 120 g/100 g in coastal soft-shell clams (Mya arenaria) in June and started to decline in July.
Economic losses:
Management decision: Shellfish closure along northern coast of Massachussetts. Continuation of the closure of Georges Bank to shellfishing.
Additional harmful effect information: Toxins that accumulated in 1990 persisted in Georges Bank surf clams (Spisula solidissima) at several hundred g/100 g, with possible slight increase in toxin levels occurring in July 1991.
Updated at 11:07 on 22 Apr 2020