Two native turtle species are in a delicate struggle for survival in a coastal river in Australia, with one of them being an invasive species. The Manning River helmeted turtle (Myuchelys purvisi), which is found only in the Manning River region of New South Wales, is under threat from the Macquarie River turtle (Emydura macquarii), which has been introduced into the area. The Macquarie River turtle is originally from several river systems across Australia and is classified as critically endangered in Victoria and vulnerable in South Australia. These turtles were first spotted in the Manning River catchment in 2007 and are thought to have been introduced through the release of pet turtles. They have now been found in nine different tributaries of the Manning River and are continuing to spread. The Macquarie River turtles are a concern for the critically endangered Bellinger River turtle (Myuchelys georgesi) and the endangered Manning River turtle. They compete with the native turtles for resources like food and can carry diseases such as the Bellinger River virus. Another major issue is hybridization — when two species interbreed — which can lead to the loss of distinct species. Evidence suggests that hybridization is already happening in the Bellinger and Kalang rivers, where the Macquarie River turtle was introduced in the 1990s. To monitor the spread of the Macquarie River turtle, researchers have developed environmental DNA (eDNA) tests. These tests detect DNA that turtles shed into river water, allowing scientists to identify the presence of specific species. In a recent study, scientists collected water samples from five locations in the Manning River catchment and used a portable eDNA backpack to filter water and capture DNA. The results from the eDNA tests and traditional snorkeling surveys were consistent, showing that Manning River turtles were present at all five locations, but no Macquarie River turtles were detected. However, more research is needed to confirm that Macquarie River turtles are not present at these sites. eDNA tests are a powerful tool for tracking the spread of species beyond their natural ranges and can help pinpoint where a target species is located. These tests can be used alongside traditional survey methods like trapping and snorkeling and can also serve as a citizen science tool, enabling the public to collect water samples and support local conservation efforts. This approach not only aids in research but also encourages community involvement in protecting native wildlife.