Platypus Citizen Science: eDNA

Audio described version

Speaker 1 (S1): Priya Crawford-Wilson, Waterwatch Coordinator

Platypus are amazing creatures that are unique to Australia. What many Melbourne residents don’t know is that platypus live of our local waterways. At Melbourne Water, we and the community have an important responsibility to look after these animals.

However, platypus are very shy, which makes it difficult to study their population size and whereabouts. We have worked with many researchers to overcome this and have developed a new system for studying platypus called Environmental DNA, or eDNA for short.

This method involves collecting a sample of water and filtering it to see if we can find platypus DNA floating around. This then gives us a good indication if platypus are living in a particular waterway. Unlike net surveys, eDNA can be conducted on any water body – wide rivers, shallow streams and even wetlands.

The collection method is quite simple. You might be collecting using a syringe directly from the water, or by using a sample bottle. Today, we’re going to use a sample bottle, as collecting directly from the water is unsafe at this location.

We need to make sure we don’t contaminate the sample in any way. To do this, we use hand sanitizer to clean our hands and before we put our gloves on.

Every site will have a unique site code, which you will need to write on the filters. For every site you will collect two filters, which gives a greater chance of detecting DNA.

Also, remember to label the filters 1 and 2. And remember not to touch either end of the filter to avoid contamination.

The next part of the process is to push the water through the syringe filter. Collect 50 ml of water in the syringe, and then attach the syringe filter. Then you simply push the full 50 ml through the filter. Unscrew the filter and refill the syringe to 50 ml and repeat the process. You need to do this several times until you have processed between 300 and 500 ml of water through each filter. You will notice that the filter becomes discoloured as it collects sediments, algae and other material, this can make pushing the water through the filter difficult.

Once you’ve completed the process, you then fill the syringe with air, and reattach the filter to blow out any remaining water. Then return the filter to it’s packet, and label with the site code, date, filter number, and volume of water collected, before repeating this process with the second filter.

Keep your filters cool so that the DNA does not degrade on the way to the lab.

All eDNA filters go to the labs at cesar Australia, where they are processed for traces of platypus mitochondrial DNA. The initial processing must take place within 48 hours of collection, after which the samples can then be frozen for later DNA extraction on the PCR. The results then tell us whether platypus occur in the waterway sampled, and provide us with a better idea of their distribution, which allows us to better protect their populations now and into the future.

Your contribution as a citizen scientist helps us in our conservation efforts, and will ultimately lead to a brighter future for platypus throughout Melbourne.

For more information on platypus, please visit the Melbourne Water and platypus spot websites.