Article and images by Alana Ebert, Mary River Catchment Coordinating Committee
We know that last summer’s savage bushfires had dire consequences for many native fauna species, but what impact did they have on our amphibious friends? Amongst some of the worst affected areas in 2019 were large swathes of wallum wetlands from Woodgate to Peregian and more recently Fraser Island (again!). These wallum swamps are home to some of our most vulnerable frog species, the Wallum sedgefrog (Litoria olongburensis), Cooloola sedgefrog (Litoria cooloolensis), Wallum rocketfrog (Litoria freycineti) and Wallum froglet (Crinia tinnula), which are only found in wallum country in northern New South Wales and southern Queensland. These habitats have been greatly impacted by coastal development, and droughts and fires add further stress on the flora and fauna of these wonderful ecosystems.
In response to the bushfires in late 2019, the federal government Department of Agriculture, Water and the Environment has provided funding for research into the impact of the fires on frog and fish of the wallum wetlands. The Mary River Catchment Coordinating Committee (MRCCC) has partnered with Griffith University, the Burnett Mary regional group, Australian and New Guinea Fishes Association and local traditional owners to conduct surveys in burnt and unburnt areas to make a comparison and some recommendations for future management.
Last month, I was privileged to join our ‘frog lady’, Eva, and knowledgeable volunteer, Mary, for four nights surveying the wetlands around Peregian and Noosa’s North Shore. Having spent a bit of time navigating Noosa’s motorways, beaches, housing estates, and abundant roundabouts, I was pleasantly surprised to find how much of Noosa remains relatively untouched by development when you veer off the beaten track a little. Being more familiar with bushwalks through rainforests and bushlands, I found the sites we surveyed were somewhat other-worldly. With no vegetation above shoulder height, other than the occasional banksia and the flower heads of prolific Xanthorrhoea, I was surprised at the beauty of this unique wonderland.
Our nocturnal surveys began after dark each night (when frogs are most active), and required us to bash through several metres of thick scrub (donning our head torches, gumboots, long sleeves and plenty of rid!) in order to make our way into the melaleuca swamps and wallum heathlands we were studying. It was tough going, tromping through unstable terrain with lots of hidden sink holes provoking more than a number of falls (luckily in a swamp you always have a soft landing!).
Between surveys, we were careful to clean our boots in order to avoid spreading the terrible fungal disease Chytridiomycosis that has been responsible for threatening the survival of many species of frogs and amphibians worldwide.
Once inside the swamps, we waded through ankle-deep (and sometimes gumboot-deep) water to survey a 50 metre transect at each site. We recorded the temperature, humidity, cloud cover, moon phase and other aspects of the weather, took water samples for testing and recorded the unique plant and animal species we could see (including plenty of frogs!), while listening hard for the presence of male frogs (as only the males call).
Eva’s keen ear for frog calls was tested with a number of unfamiliar species that aren’t normally heard around the creeks, streams and dams she would usually survey. Among these, we heard the vulnerable Litoria olongburensis, Crinia tinnula and, during a shower of rain on our final night, amongst a chorus of other species, we were thrilled to hear the call of Litoria freycineti.
We also identified a number of frogs by sight. Funnily enough, the frogs we saw were almost always of completely different species to the frogs we heard. (Lucky they’re a noisy lot!). It was fascinating to see up-close the bright blue colouring on the back of the thigh that distinguishes Litoria olongburensis from its eastern cousin, Litoria fallax. Some frogs made our task much easier by coming to greet us. At our very first site, a friendly striped rocketfrog (Litoria nasuta) climbed up Eva’s pants! This was not the first time I’ve seen frogs willingly getting up close and personal with Eva. She spends so much time around these amorous amphibians that it seems they have started to see her as kin!
The frogs of the wallum are unique in that they live and breed in and around acidic water. For this reason, they are sometimes referred to as ‘acid frogs.’ Our water samples revealed deeply tannin-stained water (like strong tea), with PH levels as low as 3.3!
All in all, we had a very successful week, collecting important data for the scientific record and even identifying some species of frogs at sites where they haven’t been recorded before. Yay! Our data and observations will be used to inform the future management of wallum wetlands, and will hopefully go some way towards protecting the incredible flora and fauna that survive in these unique ecosystems.