What’s in the water? We survey at Yundi Nature Conservancy to find out

The NGT aquatic team recently surveyed some private wetland ponds on the Fleurieu Peninsula. The ponds hadn’t been sampled for over 10 years when Nick Whiterod and Michael Hammer found populations of Southern Pygmy Perch here in 2014. This small native freshwater fish is endangered in South Australia, so we wanted to find out if they had persisted in this wetland, and what else was there.

The ponds form part of the Yundi Nature Conservancy, where owner John Fargher has been tirelessly restoring the surrounding Fleurieu Peninsula Swamps, a critically endangered ecosystem. These wetlands at John’s place, unlike the surrounding Fleurieu Swamps, are large open bodies of water. They were formed when a previous owner removed large areas of natural peat soil. Peat soil takes thousands of years to form, so the ponds will remain for the foreseeable future, presenting an opportunity for threatened fish conservation. John has done a great job improving the habitat quality of these ponds, with dense vegetation around the edges, submerged habitat like rocks and logs) and some canopy cover providing shade.

In exciting news, the Southern Pygmy Perch are doing great. The team sampled over 700 Southern Pygmy Perch (four in the eastern pool and 731 in the western pool). They also unfortunately found invasive Eastern Gambusia/Mosquito Fish, with the highest concentration in the eastern pool, where only four Southern Pygmy Perch were found. These invasive fish may be preying on juvenile Southern Pygmy Perch in the eastern pool. The Southern Pygmy Perch appear to be breeding in the western pool, sustaining their population. The next step will be genetic testing to determine the genetic origin of these fish, and whether individuals from this surrogate refuge could potentially be used in future reintroductions. The team also found a large froglet and Paratya (freshwater shrimp).