A species of turtle considered to be one of the most damaging pests in the world has been found in suburban Adelaide.
The two red-eared slider turtles were discovered by a landlord at their Plympton property in the city's south-western suburbs, abandoned by previous tenants.
The species — originally from the mid-western states of the USA and north-eastern Mexico — has the ability to quickly populate fresh water ecosystems and infect other turtle species with disease.
The importation, breeding and sale of the species is illegal in South Australia, and can attract a fine of up to $50,000 — or a one-year jail sentence — per animal.
Biosecurity SA officer Lindell Andrews said the "competitive and aggressive" and "highly invasive" pest had the potential to devastate South Australia's natural environment, particularly its waterways.
"The big deal and importance of this surrender is that these are two animals that could eventually go on to be like carp or cane toads," she said.
"They are ... classified in the top 100 most damaging pests in the world [and] they compete with native turtles for food and nesting sites."
Authorities are now searching for the turtles' previous owners.
"We're making efforts to track these people down," Ms Andrews said.
"Red-eared sliders have turned up in Australia for many years as they're part of the illegal pet trade.
"We don't see them too much in South Australia thankfully [but we have] to move quickly."
Natural Resources Adelaide Mount Lofty Ranges land marine and biodiversity manager Michaela Heinson said the turtles were the subject of eradication programs in Queensland and New South Wales.
"Escapees of deliberately released red-eared slider turtles can be extremely difficult and costly to recover," she said.
"We do rely on people to be alert for this animal and to immediately report them."
The two turtles will be euthanised.
