The Great Australian Platypus Search (GAPS) is using eDNA testing techniques to undertake the largest platypus survey ever attempted. Results from the latest round of fieldwork has just been received – and platypuses have been detected at around a third of sites sampled.
All species leave traces of DNA behind in their environment (we call this environmental DNA, or just eDNA). Using innovative new technology, we can detect these tiny traces in water samples to infer whether a species is present at a specific site.
The GAPS program is applying this eDNA detection technology to systematically investigate the occurrence of platypus over approximately 500,000 km2 of south-eastern Australia, with the team having so far visited nearly 500 sites across Victoria and NSW. Analysing the eDNA results collected we are able to then assess the impacts of major threats such as land use, altered flow regimes, and habitat degradation on platypus populations throughout the region.
A major challenge encountered by the team when undertaking this fieldwork was the impact of very dry conditions currently being experienced across south east of Australia. This resulted in approximately 40% of our selected sites having no water present, with the effect particularly apparent in western regions of Victoria and NSW.
Being unable to collect the eDNA water samples is frustrating for our field team, but more importantly these conditions render a site completely unsuitable for platypus habitation. The existence of these dry sites is particularly sad as a number were historically known to support platypus populations.
In addition to the work undertaken for the GAPS program, over 600 sites have been sampled as part of complementary projects with Melbourne Water, Wimmera CMA, Project Platypus, Upper Barwon Landcare Network, Upper Campaspe Landcare Network, North Central CMA, Glenelg-Hopkins CMA, and Blacktown City Council. This brings the total number of sites we have sampled for platypus to over 1000 and counting!
Overall, platypuses were detected at 38% of sites sampled in Victoria and 32% of those in NSW. Although it is still too early to draw many conclusions from this raw data, some trends are emerging. For instance, higher platypus occurrence is associated with native vegetation cover, high in-stream complexity (good habitat for macroinvertebrates) and suitable burrowing habitat.
The next batch of eDNA water samples from the spring 2019 field season (targeting the platypus breeding period) has already been collected and will be processed by our laboratory team shortly.
To stay up to date on the latest GAPS results, follow platypusSPOT on Facebook or Twitter. Don’t forget, you can also contribute to this amazing project by recording any platypus sightings at www.platypusSPOT.org or via the platypusSPOT app (apple or android).
The Great Australian Platypus Search is collaboration between cesar, San Diego Zoo Global, and the University of Melbourne.