Murray River turtle habitats freshened by floodwater but nests could drown
Murray River floodwater could lead to an increase in freshwater turtle numbers, as temporary wetlands and creeks are filled to provide new habitats and food sources for the threatened species.
Key points:
- Floodwater is creating new temporary habitats for freshwater turtles
- There are concerns already established turtle nests might be drowned by floods
- Turtle monitoring is underway to protect the native creatures from predators
Researchers say it could even lead to a double clutch nesting event, with the possibility of some turtles laying a second nest later this season after gaining extra energy from increased food availability.
But it's not all good news for the slow-moving native creature, with the potential for existing nests to be drowned by rising water levels.
La Trobe University biomedical sciences senior lecturer James Van Dyke, who has studied turtles in Australia and the United States for 15 years, has focused on Murray River turtles for the past seven years.
"The reality is a lot of those nests are usually destroyed by foxes anyway, we always have very high levels of egg mortality in turtles," he said.
James van Dyke says some turtle species have declined in numbers by up to 90 per cent. (ABC Riverland: Catherine Heuzenroeder)
"The floods might impact those [mortality] levels ... but the extra flooded habitats means adult turtles will be having a really good year with all the extra bugs, plants and carrion they can eat."
He said while blackwater was starting to be seen in some parts of the river system, turtles would not be impacted as they breathed oxygen and were like the "vacuum cleaners of the river".
"Alongside other animals, they'll be eating the carrion, anything that dies in the blackwater, they'll be very happy to be eating it and helping to clean up," he said.
Citizen scientists nurture turtle nests
Dr Van Dyke said his turtle surveying in the South Australian leg of the Murray River had revealed a decline in numbers due to fox predation, changing river flows and high road mortality rates.
Wire or plastic mesh can be used in some states to protect turtle nests from foxes. (Supplied: Steve Rodley)
"Riverglades in Murray Bridge, around Berri and Lake Bonney in Barmera are all really good turtle spots, but in between those areas there's pockets where there aren't any turtles anymore,"he said.
Citizen science monitoring is ramping up to keep a track of nest numbers in South Australia.
Mid Murray Landcare project manager Aimee Linkee said she was working with landholders around Devon Downs to locate, monitor and protect turtle nest sites from foxes.
Wild turtle sightings can be recorded on TurtleSAT, a data mapping collection website. (Supplied: Angela Simms)
"They like to nest in sandy areas without any tree cover above the usual flood level, which can be within five metres of the water or hundreds of metres to find a spot they like, so they're hard to find," she said.
Ms Linkee said she hoped to install cameras at the nesting sites to keep a closer eye and help protect the native creatures.
"We want to stop them being predated on all the time, or set up enclosures or some kind of protection to actually try and get some recruitment of turtles back into the river system,"she said.