General Information

Event name: GB-92-004
Nature of the harmful event:
Seafood toxins
Event directly affected:
Toxicity detected: Yes (Approximate range: 1540 mu.)
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 (PSP detected in Orkneys during 1990 and 1991)
Individuals to contact: HOWARD, Godfrey , MACDONALD, Elspeth

Location & Date

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Location: Latitude: , Longitude:
General location information: Orkney and Shetland Islands., Scotland.
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:


Causative organism known: Yes
Causative Species/Genus: Alexandrium spp. (2,140 cells/L)
Maximum cel density.
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information: Alexandrium spp. found in samples from Shapinsay, Scapa Flow and Carness.
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 Comments Not known.
Additional Environmental information: No detailed information available.

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Queen Scallops Saxitoxins 400 - 600 mu Bioassay-Mouse
Velvet crabs Saxitoxins Bioassay-Mouse
Crustaceans Saxitoxins Bioassay-Mouse
Mussels Saxitoxins 215 ug/100g Bioassay-Mouse
Kit used: Type of kit used:
Additional information: 1991 PSP outbreak in Orkney extended into 1992. By end January, levels in scallops had fallen below 400 mu. Sampling resumed in April and by end April, 600 mu detected in mussels from Scapa Flow. Peak levels (1540 mu) detected at end of May and remained over 400 mu until mid-July, when they dropped rapidly. North of mainland Orkney, scallop gonads exceeded 400 mu on 22 June. Mussels and queen scallops found with levels exceeding 1000 mu during July, but had fallen below 400 mu by end July. PSP toxins detected in queen scallops until September. One scallop gonad sample from Shetland tested positive for PSP toxins (348 mu). Velvet crabs remained toxic in January with levels of 680 mu detected before falling below 400 mu by the end of January. Toxicity was found in crustaceans at lower levels from May to October.
Economic losses:
Management decision: Closures applied as necessary.
Additional harmful effect information:
Updated at 09:41 on 9 Oct 2020