General Information

Event name: ZAF-94-001
Nature of the harmful event:
High Phyto concentration , Mass mortalities
Event directly affected:
Natural Fish , Shellfish
Toxicity detected: No
Associated syndrome: OTHER
Unexplained toxicity: No
Species implicated in toxin transmission (transvector):
Report the outcome of a monitoring programme: No
Event occurred before in this location: Yes (But first recorded incidence of hydrogen sulphide poisoning causing black discolouration of the sea)
Individuals to contact: MANSFIELD, Lisa

Location & Date

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Location: Latitude: -32.758056, Longitude: 18.066389
General location information: St Helena Bay to Cape Town, West Coast
HAB Area code(s): ZAF-01
Additional location information:
Bloom event dates (yyyy/mm/dd): Event Date:1994-03-01
Start: 1994-02-11, End: 1994-03-21
Quarantine levels dates (yyyy/mm/dd): First detection: 1994-03-14, End: 1994-03-21
Additional date-related information:


Causative organism known: Yes
Causative Species/Genus: Prorocentrum micans (7 x 10e6 cells/L)
Ceratium furca (7 x 10e6 cells/L)
Co-Ocurring Species/Genus: Dinophysis acuminata ( cells/L)
lower cell concentrations
Alexandrium catenella ( cells/L)
lower cell concentrations
Chlorophyll concentration, if known: µg/l
Additional bloom information: black water and hydrogen sulphide poisoning
Event-related bibliography: MATTHEWS, S.G. and G.C. PITCHER 1996 - Worst recorded marine mortality on the South African coast. In Harmful and Toxic Algal Blooms. Yasumoto, T., Y. Oshima and Y. Fukuyo (Eds). Intergovernmental Oceanographic Commission of UNESCO

Environmental Conditions

Weather: Turbidity (NTU): Wind direction: SE
Stratified water: Oxygen content (nL/L): <0.5 Wind velocity:
Temperature (°C): Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: Current Velocity:
Nutrient information:
Temperature Range During Event: Max: °C, Min: °C
Salinity Range During Event:
Bloom location in the water column:
Growth: Advected
Growth Comments The bloom was initially observed around Dwarskersbos on 11 February and Elands Bay on 16 February. By 21 March it had been transported south to Cape Town.
Additional Environmental information:

Toxin Assay Information

Species containing the toxin Toxin type Toxin details Max. concentration Assay type
Kit used: Type of kit used:
Additional information:
Economic losses: Approximately 60 tons of rock lobster and 1500 tons of fish (comprised mainly of the mullet, Liza richardsoni) washed ashore during this bloom.
Management decision: Due to the fishing companies and canning factories temporarily laying off seasonal workers, a fund was set up to relieve their financial difficulties and rock lobster fishermen were allowed access to alternate catching areas.
Additional harmful effect information: Some sharks and bottom-dwelling fish also died. Surveys of the rocky shore revealed that most mussels, limpets, sea urchins and other intertidal life had died.
Created at 11:05 on 27 Sep 2017
Updated at 06:45 on 13 Nov 2018