Historical Record of Coastal Algal and Marine Stress Events in South Australia.
Executive Summary
Historical records confirm repeated coastal observations of water discolouration, fish mortality, and harmful algal events in South Australia over more than a century.
“Discoloured water caused by plankton blooms has been recorded periodically in South Australian coastal waters since the early twentieth century.” [A]
Documented events show consistent environmental drivers including nutrient availability, water temperature, and water column stability. The record also includes specific fin-fish mortality events in both tuna and kingfish aquaculture.
These records support that the events are recurring system responses, not isolated incidents.
1 Forward Timeline (Source Anchored)
1800s
“An extensive growth of confervoid vegetation coloured the waters of Lake Alexandrina green.” [B]
“The water assumed a green colour and emitted an offensive odour.” [C]
Early 1900s
“Discoloured water caused by plankton blooms has been recorded periodically in South Australian coastal waters since the early twentieth century.” [A]
1956–1959 (Murray Flood Period)
“Muddy water extended far out to sea from the Murray Mouth following flood discharge.” [D]
“Large volumes of freshwater entered the coastal zone, significantly altering salinity conditions.” [E]
“Fish kills were reported in the lower river and estuarine regions during and after the flood.” [F]
“Floodwaters carried heavy loads of silt and organic matter into coastal waters.” [G]
1987
“In 1987 a bloom of Alexandrium catenella in Gulf St Vincent caused paralytic shellfish poisoning and led to the closure of shellfish harvesting areas.” [H]
1996
“Mass mortality of captive southern bluefin tuna occurred in Boston Bay, South Australia, in April–May 1996.” [I]
“The event represented a complex diagnostic problem involving several environmental factors.” [J]