General Information

Event name: CA-00-009
Country: CANADA
Nature of the harmful event:
Seafood toxins
Event directly affected:
Aquaculture Fish , Shellfish
Toxicity detected: Yes (Approximate range: max.=155 g STXeq /g wet wight of plankton (> 20 um))
Associated syndrome: PSP
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: No
Event occurred before in this location: Yes (Although Alexandrium tamarense has been observed in this area in other years this was the first time a significant bloom occurred. No previous fish kills associated with Alexandrium.)
Individuals to contact: CEMBELLA, Allan , LEWIS, Nancy

Location & Date

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Location: Latitude: 43.750000, Longitude: -65.319167
General location information: Southwestern Shore of Nova Scotia, Scotia Fundy Region
HAB Area code(s): CA-18
Additional location information: The bloom occurred at a salmon aquaculture site located in a small enclosed harbour close to the town of Shelburne. There is a small boatyard near the site where dumping of ballast water has occurred. For many years scallop fisherman have fished offshore from this harbour possibly introducing cells from offshore scallop grounds.
Bloom event dates (yyyy/mm/dd): Start: 2000-06-02, End: 2000-06-14
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information: The bloom was detected when mass mortalities of fish were observed at the aquaculture site. The growers observed fish near surface, lethargic and swimming opposite to the school. Dead fish showed irritation around the gill.

Microalgae

Causative organism known: Yes
Causative Species/Genus: Alexandrium tamarense (825,000 cells/L)
Co-Ocurring Species/Genus: Scrippsiella trochoidea (<1,000 cells/L)
Chlorophyll concentration, if known: Chlorophyll concentration was not measured at µg/l
Additional bloom information: Although the bloom was almost monospecific a few other large dinoflagellates were observed in concentraions <1000 cells/l including Ceratium longipes. Dinophysis norvegica, and Gyrodinium spirale.
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: 17 °C, Min: 8 °C
Salinity Range During Event: Max: 30, Min: 19
Bloom location in the water column:
Subsurface
Growth:
Growth Comments The origin of the bloom is not certain, although it could have been advected into the harbour, the species has occurred at this location in other years and there may be cysts present in the sediment.
Additional Environmental information: Temperature and salinity data from CTD cast 0-8 metres, 09 June 2001. There had been a significant rainfall previous to the death of the fish. The water was brackish, and brown in colour indicating runoff. CTD casts showed a pronounced halocline.

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Mytilus sp. Saxitoxins STX eq 43,767 g/kg LC
Kit used: Type of kit used:
Additional information: HPLC-FD: GTX, STX analised. C's not analysed.
Economic losses: 15,000 $US direct loss of product
Management decision: None taken fish kill event see related CA-00-009
Additional harmful effect information: Positive AOAC mouse bioassay
Updated at 03:47 on 27 Sep 2018
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