General Information

Event name: ZAF-77-001
Nature of the harmful event:
Water Discoloration , High Phyto concentration
Event directly affected:
Toxicity detected: No
Associated syndrome: OTHER
Unexplained toxicity:
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

[View larger map]
Location: Latitude: -32.759444, Longitude: 18.101667
General location information: St Helena Bay, West Coast
HAB Area code(s): ZAF-01
Additional location information:
Bloom event dates (yyyy/mm/dd): Event Date:1977-11-22
Start: 1977-11-22, End: 1977-11-23
Quarantine levels dates (yyyy/mm/dd):
Additional date-related information:


Causative organism known: Yes
Causative Species/Genus: Mesodinium rubrum (666670 cells/L)
recorded at station 2, 300 m off shore
Co-Ocurring Species/Genus: Skeletonema costatum (22749090 cells/L)
recorded at station 2, 300 m off shore
Chlorophyll concentration, if known: 3,47 - 123,40 µg/l
Additional bloom information: Mesodinium rubrum comprised only 5% of the total phytoplankton population at station 1, but was sufficient to dicolour the water a deep maroon.
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: calm hot Turbidity (NTU): Wind direction: S
Stratified water: Yes Oxygen content (nL/L): 3,30 - 9,97 Wind velocity: 0 - 6 m/second
Temperature (°C): 14 - 15 Oxygen saturation %: Current Direction:
Sechhi disk (m): Salinity: 34,67 - 34,69 Current Velocity:
Nutrient information: NITRATE: 0,4 - 14,9g-at/L
PHOSPHATE: 0,8 - 3,4g-at/L
SILICATE: 2,8 - 38,9g-at/L
Temperature Range During Event: Max: 15 °C, Min: 14 °C
Salinity Range During Event: Max: 34,69, Min: 34,67
Bloom location in the water column:
Growth Comments
Additional Environmental information: Strong, shallow thermocline at 5-8 m.

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:
Management decision:
Additional harmful effect information:
Created at 02:52 on 3 Oct 2017
Updated at 07:00 on 13 Nov 2018