Platypuses in the MacKenzie River
14 July, 2015
Platypuses were once widespread in the Wimmera Catchment. But now, the MacKenzie River flowing to the west of the Grampians supports the last known resident population in the catchment (although we have received occasional sightings elsewhere via platypusSPOT, platypusspot.org/view-sightings/id/197). cesar and the Wimmera Catchment Management Authority have been keeping a close eye on this small population for the past 7 years. It has proved remarkably resilient, surviving drought, then severe flooding, as well as several bushfires along the way. An environmental flow program implemented by the WCMA has undoubtedly helped this population to persist through these disturbances by providing reliable water in the upper MacKenzie.
Recently, we have seen the population starting to increase. Results from surveys in April 2014 were the best in years and included the first juveniles recorded since 2006. Earlier this year, we returned to survey the area with good results again. Two more juveniles were captured indicating this small and vulnerable population is slowly heading in the right direction.
We also looked at platypus distribution in the MacKenzie River by screening water samples for platypus DNA, an innovative technique known as environmental DNA (eDNA). Live-trapping surveys of platypuses are very labour intensive, so this novel technique can provide a quick and more economical assessment of whether platypuses are present. The eDNA results largely reflected what we know of the MacKenzie system from current and previous trapping efforts, confirming eDNA can be a reliable and cost-effective technique to monitor platypus distribution.
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