Thirty participants joined an MCMC event, intriguingly named “Are there Platypus in Merri Creek?” in early May 2021 at the CERES Environmental Park in Brunswick East, by Merri Creek.
The event began with a presentation by Josh Griffiths from Cesar Australia about Platypus - their distribution, biology, diet, habitat requirements and current threats. The latter include loss of waterway habitat (removal of instream and bank vegetation) and the impact of 'urban stream syndrome', the combined effect of stormwater pollutants and too frequent high flows. Josh discussed the monitoring of platypus and how this is changing to be less invasive, including use of the citizen science Platypus spot app and of DNA to detect Platypus in waterways.
Participants then walked down to the Merri Creek for an interactive session on waterbugs (aquatic macro invertebrates), which are the main food source of Platypus. Live waterbug samples from nearby Jones Park wetland and downstream on the Merri Creek were avilable for participants to look at.
Many participants had fun donning gumboots and stepping into a riffle section in the creek to collect more waterbugs, learning the “sweep” and “kick” method of sampling that the citizen science Waterwatch program uses for its waterbug monitoring program. The sample collected from the Merri showed a low diversity of species and a low population of waterbugs overall, unfortunately typical for this section of the Merri Creek, and probably the reason for the paucity of Platypus in the Merri. (See summaries of other water quality tests.)
Platypus eat approximately half their body weight in waterbugs daily, anywhere from to 750gm to over 1kg, depending on the age and sex of the Platypus. Many urban streams, including the Merri Creek, have low numbers of waterbugs, insufficient to support Platypus breeding populations.
The last reported community of a platypus in the Merri Creek was in Janaury 2017, in Coburg North. This sighting and others are stored on the Platypus spot app which collects citizen science data on platypus sightings. It is free to download and everyone is encouraged to add any Merri Creek platypus sightings.
Many people expressed interest in participating in Citizen Science Platypus monitoring, especially collecting eDNA (environmental DNA) samples. Josh showed how such water samples are collected and filtered for DNA before they are sent to a lab for analysis for the presence of Platypus DNA.
MCMC will inform the local community when opportunities for citizen science colllection of eDNA samples arise.
Some of the feedback received included:
“Thank you [for running this event] more of the same!”
“I enjoyed the mix of presentation and practical [activities]”
“Thank you, we love your work!”
“Loved the cross group collaboration”.
Thank you to Melbourne Water for providing funding to MCMC to host this event.