General Information

Event name: ZAF-89-001
Nature of the harmful event:
Water Discoloration , High Phyto concentration , Mass mortalities
Event directly affected:
Natural Fish , Shellfish , Humans
Toxicity detected: Yes (Approximate range: Range not specified)
Associated syndrome: OTHER , Aerosolized toxins effects
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: No
Event occurred before in this location: Yes (A similar event was seen in 1988)
Individuals to contact: MANSFIELD, Lisa

Location & Date

[View larger map]
Location: Latitude: -34.229167, Longitude: 18.695556
General location information: False Bay, South Coast
HAB Area code(s): ZAF-02
Additional location information: The mortalities from this bloom spread from Fish Hoek to as far as Pearly Beach.
Bloom event dates (yyyy/mm/dd): Event Date:1989-03-10
Start: 1989-03-10, End: 1989-03-25
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information:


Causative organism known: Yes
Causative Species/Genus: Gymnodinium sp Horstman et al. 1991 (24707828 cells/L)
on 1989-03-13 Gordons Bay
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: µg/l
Additional bloom information:
Event-related bibliography: HORSTMAN, D.A., S. MCGIBBON, G.C. PITCHER, D. CALDER, L. HUTCHINGS and P. WILLIAMS 1991 Red tides in False Bay, 1959-1989, with particular reference to recent blooms of Gymnodinium sp. Transactions of the Royal Society of South Africa 47: 611-628.

Environmental Conditions

Weather: calm Turbidity (NTU): Wind direction:
Stratified water: Oxygen content (nL/L): Wind velocity:
Temperature (°C): 12.5 - 20.0 Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: Current Velocity:
Nutrient information: NITRATE: 0.0 - 19.7 mmol.m-3
Temperature Range During Event: Max: 20.0 °C, Min: 12.5 °C
Salinity Range During Event:
Bloom location in the water column: Whole column
Growth: Advected
Growth Comments ... the initial mortalities at Fish Hoek spread as far as Pearly Beach...
Additional Environmental information: Bathers and fishermen suffered from eye, nose and lung irritations during the bloom.

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Gymnodinium sp Brevetoxins Bioassay-Other
Kit used: Type of kit used:
Additional information: A sea-urchin assay was performed
Economic losses: An estimated 40 tons of wild abalone were washed up on the shore during this bloom.
Management decision:
Additional harmful effect information: Bathers and fishermen suffered from eye, nose and lung irritations during the bloom.
Created at 09:27 on 19 Apr 2018
Updated at 09:56 on 25 Aug 2020