Determining the geographic spread, presence, and absence of a species is integral to making informed biodiversity management decisions. Traditional methods of species detection can be time consuming, expensive, logistically difficult, and invasive – limiting opportunities for wide-scale, frequent biodiversity surveys, and consequently reducing information available to environmental managers. Environmental DNA sampling and subsequent metabarcoding analysis is a sensitive, cost-effective, and efficient method which can cover large spatial and temporal scales to gather biodiversity data. The Great Australian Wildlife Search (GAWS) is a large citizen science program, led by Odonata Foundation in partnership with EnviroDNA, that aims to map and monitor aquatic vertebrate biodiversity across Australia utilising the power of eDNA methods. The first phase of the program mapped aquatic vertebrate biodiversity in Victoria across over 1800 sites in Spring 2021.
In Spring 2023 and 2024, in partnership with the Murray-Darling Basin Authority, GAWS moved to the Murray-Darling Basin where ~500 waterway sites were sampled across the multiple states. Our presentation will summarise how each sample underwent eDNA metabarcoding analyses targeting fish and vertebrate taxa using a suite of metabarcoding assays. Of the ~1000 water samples collected, our data detected native and invasive fish species, including EPBC listed threatened species, across the Murray Darling Basin. The multiple metabarcoding assays deployed improved detection of fish taxa, highlighting the value of multi-amplicon approaches. GAWS is a case study that highlights the effectiveness of eDNA in biodiversity baselining and surveillance across a large geospatial spread. The techniques used could also be applied in areas such as fisheries management and monitoring the impact of extreme events on aquatic ecosystems and their populations.