General Information

Event name: ZAF-78-001
Nature of the harmful event:
Water Discoloration , High Phyto concentration , Mass mortalities
Event directly affected:
Natural Fish
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: No
Individuals to contact: MANSFIELD, Lisa

Location & Date

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Location: Latitude: -32.759167, Longitude: 18.101667
General location information: St Helena Bay, West Coast
HAB Area code(s): ZAF-01
Additional location information: Red water from Elands Bay to Dassen Island
Bloom event dates (yyyy/mm/dd): Event Date:1978-04-01
Start: 1978-04-01, End: 1978-04-07
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information:


Causative organism known: Yes
Causative Species/Genus: Mesodinium rubrum ( cells/L)
Co-Ocurring Species/Genus:
Chlorophyll concentration, if known: 12.96 - 3.20 µg/l
Additional bloom information: Chlorophyll range recorded on 6th and 7th April. Data is misleading and probably sampled outside of bloom.
Event-related bibliography: HORSTMAN, D.A. 1981 Reported red-water outbreaks and their effects on fauna of the west and south coasts of South Africa, 1959-1980. Fish. Bull. S. Afr. 15: 71-88.

Environmental Conditions

Weather: hot and calm sea Turbidity (NTU): Wind direction: S
Stratified water: Oxygen content (nL/L): 1.09 - 7.36 Wind velocity: 15 m/second
Temperature (°C): 15.40 - 14.30 Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: 34.59 - 34.70 Current Velocity:
Nutrient information: NITRATE: 9.0 - 1.0g-at/L
PHOSPHATE: 18.2 - 2.8g-at/L
SILICATE: 53.2 - 24.6g-at/L
Temperature Range During Event: Max: °C, Min: °C
Salinity Range During Event:
Bloom location in the water column:
Growth Comments
Additional Environmental information: Effect of a southerly wind on 7 April caused a slight recovery of oxygen content of water at station 1 and displace low-oxygen water father off shore.

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: Damage to the west coast rock lobster, Jasus lalandii, industry as large numbers washed ashore.
Management decision:
Additional harmful effect information: Hypoxia, causing many rock lobsters, natural fish and sharks as well as thousands of sea urchins to wash ashore.
Created at 12:21 on 3 Oct 2017
Updated at 06:49 on 13 Nov 2018