One way to help determine if platypus occur in a stream is via netting. Here, fyke nets at set up before dusk and then are checked every 3–4 hours until dawn, at which time they are taken down and removed.

The first part of looking for environmental DNA is collecting a water sample. Here, Lisa Kirkland, a member of the research team for EnviroDNA, draws up a sample of water in a syringe . This sample will then be refrigerated and transported to the laboratory for analysis.

Student volunteer Jessica Pulvirenti measures the bill dimensions of a captured platypus, as Josh Griffths helps holds this monotreme still. Such data is used to help compare morphological differences that may exist between populations.

Platypus ecologist Josh Griffiths gives the captured platypus a thorough examination, looking for any injuries or signs of disease, and checks overall body condition. 

Having been captured, measured and tagged just 20 minutes earlier, a released female platypus starts heading down stream, most likely back to her burrow.

A female platypus hesitates on a log sitting beside a river, before finally clambering over it and heading into the water.

After an in-field water sample is collected, it is passed through a very fine filter to collect any cellular material. EnviroDNA geneticist Anthony van Rooyen starts the process of extracting any potential DNA fragments that may have been trapped from a river sample. 

Once any eDNA has been extracted from a water sample, it is prepared in triplicate, ready for quantitaive PCR (polymerase chain reaction) analysis. Sometimes called ‘molecular photocopying,’ PCR is a fast and inexpensive technique used to amplify small segments of DNA.

Researchers review the data from a river water sample to determine whether any traces of platypus DNA exist. Just a small trace means good news, and there are definitely platypus upstream.