eDNA Unlocking Secrets of the Cudgegong River

Published 14th January 2025. Written by Maddison O’Brien

In November 2024, Watershed Landcare once again joined the Great Australian Wildlife Search (GAWS), a groundbreaking initiative that engages citizen scientists to explore and map the hidden biodiversity in our waterways. This year marks the second time Watershed Landcare has participated in the program, with the group returning to several sites along the Cudgegong River and Lawson Creek for follow-up testing. Such long-term monitoring is critical for understanding the health of our local ecosystems and guiding conservation efforts.

The project uses cutting-edge environmental DNA (eDNA) technology, which allows scientists to detect traces of DNA left behind by animals in water samples. Local Landcare Coordinator Maddi O’Brien, joined by volunteers Emily Stone and John McCrae, collected water samples at key locations of interest. Equipped with sampling kits provided by the program, the team worked diligently at the water’s edge, pulling water samples into large syringes before filtering the water to capture sediments containing DNA. The filters, carefully preserved, were sent to EnviroDNA labs in Victoria for analysis.

Maddi O’Brien with Landcare legends John McCrea and Emily Stone, collecting eDNA samples from the Cudgegong River to uncover hidden biodiversity.

“The process is fascinating,” said Maddi O’Brien. “The filters capture DNA traces from any animals that have been in or around the water, giving us an incredibly accurate snapshot of the ecosystem. Last year, our testing revealed the presence of platypus, native fish like galaxias and river blackfish, and even the rakali, a native water rat. The results help us track changes in biodiversity and guide our efforts to improve habitat conditions.”

Emily Stone collects water samples from the Cudgegong River, getting hands-on with eDNA to uncover the river’s hidden wildlife.

This year, Watershed Landcare’s participation builds on the success of their 2023 efforts. Results from last year’s sampling led to on-ground actions such as tree planting and weed control along the Upper Lawson Creek and Cudgegong River. These initiatives aim to support vital native species like the Murray cod and galaxias by enhancing and preserving their habitat.

“This kind of follow-up testing is so important,” Maddi added. “It helps us see the impact of our conservation work over time and highlights areas that need more attention.”

GAWS, led by the Odonata Foundation and supported by Illumina Inc. and the Murray-Darling Basin Authority, represents a powerful collaboration between science and community. Across eastern Australia, citizen scientists are collecting water samples at 190 sites, contributing data that is reshaping how ecosystems are monitored. In 2023, the project detected six threatened fish species, four threatened mammals, and 40 native bird species. The technology’s ability to pinpoint the presence of species with precision has already made a tangible difference.

Watershed Landcare is proud to play a role in this pioneering project and looks forward to continuing its partnership with GAWS. “It’s an amazing opportunity to connect with our local environment and make a real difference for our rivers,” Maddi said. “We’re excited to see what this year’s results reveal.”