RESEARCHERS at the University of Adelaide have found that risks to water quality from the carp virus would be "minimal" in some inland waterways and "manageable" in others.
"If the carp virus is released to control carp, the ecosystem will need to cope with a surge in the number of dead carp, an increased demand for dissolved oxygen and the presence of more nutrients," principal investigator Justin Brooks said.
"This work has shown the impacts on water quality would be minimal in many waterways where there is good flow and mixing and manageable where the flow is slower."
The study's models show that areas with good flow, depth and cooler waters would likely cope best, whereas shallower waters with low or no flow and warmer temperatures are more likely to experience water quality impacts, especially if the density of carp is high.
These water bodies might require some intervention to clean up dead carp to avoid significant impacts on water quality.
The main threats to water quality include a reduction in the concentration of oxygen in the water and the possibility of associated algal blooms.
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The first is due to the oxygen consumption of organisms working to decompose dead carp, whereas the second is a result of an increase of nutrients present in the water as dead carp break down.
The research showed that at the existing biomass of carp, it would be unlikely that oxygen concentrations would drop below levels that are dangerous for native fish in most waterways.
In many locations, the research showed that the existing biomass of carp would have to be increased by more than four times before water quality impacts would become noticeable.
The research means that management of carp carcasses can focus on the higher risk sites which have still water and higher temperatures.
This research project is an important part of the National Carp Control Plan - a $10.2-million program led by the Fisheries Research and Development Corporation, on behalf of the federal government.
The NCCP was formed to investigate the feasibility of releasing a virus to control carp in Australian waterways.
The final plan will be presented to the government in December, after which the government will decide on the next steps.
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