Date posted: 15 January 2015
The Environment Protection Authority (EPA) has advised that the introduced pest European carp found dead in Adelaide Botanic Garden died as a result of recent weather events.
The rainfall on 10 and 11 January is suspected to be a contributing factor, flushing anaerobic water and sediments down Botanic Creek and into the Adelaide Botanic Garden lake system.
Following testing it is believed that low dissolved oxygen levels in the water caused the deaths.
Similar events caused by low oxygen levels occur frequently throughout South Australia and other states when heavy rains wash organic material from catchments into waterways.
Dead European carp were first noticed in the Main Lake on Saturday, 10 January.
It appears only large fish were killed in the incident as a smaller pest fish species, Mosquitofish, and several tortoises were not affected and remain widely distributed among the lakes in Adelaide Botanic Garden.
All dead fish have been removed by Botanic Gardens staff who will continue to monitor the area.
Biosecurity SA was advised immediately following the discovery and collected water and fish samples for possible further testing.
It is possible that additional dead European carp will surface from the bottom of the lakes over the coming week, plans are in place for their removal.