General Information

Event name: GB-94-005
Nature of the harmful event:
Seafood toxins
Event directly affected:
Toxicity detected: Yes (Approximate range: 5,040 mu.)
Associated syndrome: PSP
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: Yes (SOAFD Monitoring Programme.)
Event occurred before in this location: Yes (Regular occurrence since 1990.)
Individuals to contact: HOWARD, Godfrey , MACDONALD, Elspeth

Location & Date

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Location: Latitude: , Longitude:
General location information: , Orkney Islands.
HAB Area code(s): GB-20
Additional location information:
Bloom event dates (yyyy/mm/dd):
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information: Early May - September. Six closure orders were enforced beginning on 21st May and finally lifted on 17th September.


Causative organism known: Yes
Causative Species/Genus: Alexandrium sp. (< 1,000 cells/L)
Alexandrium cf. Tamarense. Waulkmill Bay
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information:
Event-related bibliography:

Environmental Conditions

Weather: Summer weather was generally cool and wet. 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:
In situ
Growth Comments There is a small population of Alexandrium cysts in parts of Scapa Flow, so in some cases, toxicity could be caused by in-situ populations.
Additional Environmental information: No detailed information.

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Kit used: No Type of kit used:
Additional information: PSP toxins detected in pectinids, mussels and razor fish from many sites in the area. Maximum toxicity (5,040 mu) was recorded in early June and although levels then declined, they did not drop below 400 mu until early September.
Economic losses:
Management decision: Six closure orders were enforced beginning on 21st May and finally lifted on 17th September.
Additional harmful effect information: PSP toxins were also detected in brown crab and lobsters but were found to be mainly < 400 mu. Velvel crabs had toxin levels up to 1924 mu. No action necessary, as fisherman imposed a voluntary closed season.
Updated at 10:50 on 14 Sep 2016