Dr Fanny de Busserolles takes a water sample from the creek for the eDNA survey (credit: SOWN).

A Mix of Locals, Invasives and Absentees

There’s good news here. Native fish such as the purple-spotted gudgeon, eel-tailed catfish, australian bass, and western carp gudgeon were found at various sites. There were also positive markers for the tusked frog at both sites in Fish Creek, and similarly the Stony Creek Frog at Walton Bridge. Our surveys also detected two species of turtles, two species of eel, and freshwater invertebrates like daphnia, freshwater shrimp, and freshwater prawn—essential building blocks of the aquatic food web.

However, the surveys also picked up numerous invasive species. For example, the Eastern mosquitofish appeared at multiple sites. The invasive cane toad also made a strong appearance. And the most commonly detected mammal? The dog. With a presence far exceeding any native mammal species, could it be having an impact more serious than previously recognised?

Some macroinvertebrates typically associated with healthy creek systems and beneficial to the platypus were also low or undetected in this round. These gaps could point to water quality or habitat limitations that may be restricting biodiversity in parts of the catchment, and warrant further consideration by our expert advisors.

Creek Creatures: From native fish like gudgeons to tiny invertebrates, this collage highlights some of the species identified through the eDNA surveys (compilation: Wilderlabs, image sources: Wikipedia

Where Did the Platypus Go?

At the heart of this work is a bigger question: Can we bring platypus back to our creek?

No platypus DNA was detected in this survey.  However, historically platypus are known to have inhabited Enoggera and Fish Creeks.  Long-term Gap residents share stories of seeing platypus in the 80’s and 90’s, such as under the School Road Bridge or in Fish Creek near St Peter Chanel School.

Have you ever seen a platypus in The Gap? Over the past 20 years, data from the Platyproject shows only a handful of possible sightings in our suburb. However, it’s important to note that most of these reports have not been verified, and recent evidence suggests that many of them were more likely rakali (native water rats) rather than platypus.

To further clarify, local platypus expert Dr Tamielle Brunt has conducted extensive environmental DNA sampling in the creek over the past few years, specifically looking for signs of platypus. Despite thorough efforts, no platypus DNA has ever been detected.

Today, their presence seems to have all but vanished. It is likely a mix of habitat loss, pollution, predation, climate change, and other urban pressures.

This eDNA project gives us a baseline for what’s present now in the ecosystem, and clues about what needs to be done if we hope to see platypus return.  Rewilding the platypus isn’t a simple task but it would be a powerful sign of a healthy creek and recognition of the patient, meaningful work that many in our community do to help restore and steward our beautiful waterways.

Join the Movement: Help Monitor Our Creeks

You can help us learn more! The Gap Sustainability Initiative and SOWN are running monthly community creek surveys that are family friendly. These surveys don’t use DNA technology—instead we get hands-on: collecting macroinvertebrates (ie. little creek critters), then sorting and recording what we see. It’s a fantastic way to learn something new (we’ll show you how), meet like-minded locals, and make observations that help us understand the creek’s changing conditions. See you there!

Location:         Fursman Crossing Park, Yooralla Street The Gap

When:              Monthly — every 3rd Sunday of the month 8.30 – 10.30am*

*This is weather dependent so always check our Facebook Page for the latest information