The Illawarra's most famous threatened species may have found unique benefits to co-existing with humans and heavy industry, reports BEN LANGFORD
What if co-existence with heavy industry can actually benefit one of our most endangered species? For the green and golden bell frog, it seems a combination of salty sea spray and possibly chemical runoff could actually help it survive a fungus which looms as the greatest threat to its survival.
Sounds far-fetched, perhaps. And this is not to suggest native animals aren’t better off in the wilderness. But the eastern seaboard habitat of this large native frog is no longer wilderness, and it has shown a fussiness regarding living quarters on par with most coastal property owners. More recently, the addition of an introduced fungus has created the perfect storm to threaten a bell frog’s survival. And desperate times call for whatever measures work.
But first let’s get to know our subject. It can be beloved or loathed, depending on your point of view. Not because of its nature (fussy but shy, curious) or appearance (the bright pea-and-brass brown colouring is attractive and a unique identifier like a fingerprint; this is no warty, poisonous toad). It’s because, perhaps more than any other creature in the greater Illawarra region, the green and golden bell frog has provided a thorn in the side for development.
For some reason we may expect a threatened species to be small. This one is not. Adults are in the 45mm-110mm range, making it a fairly large frog.
It is neither named nor loved its call. Don’t go listening out for the sound of a brilliantly cute ringing bell. You will not find it. Rather, this frog’s call sounds more like a “grumpy chicken”, said Lachlan Wilmott, a threatened species officer with the NSW Office of Environment and Heritage. Others might say it sounds like a drunken duck staggering home. Search YouTube for examples and try not to cackle.
Its status as a threatened species has meant its presence must be taken seriously. But this has come late for the green and golden bell frog, which has experienced a 90 per cent contraction in range since 1990 (although researchers estimate it probably started at least a decade prior to this).
Once found on the southern and central tablelands and the western slopes of NSW, ths frog is now only found near the coast, at sea level, with communities sometimes as small as just five adults.
The green and golden bell frog first gained notoriety in the late 1990s as its discovery at Homebush halted construction of the Olympic tennis courts, which were then built in another location.
In early 2012, then Gilmore MP Joanna Gash actually suggested the frog be removed from the threatened species list because its presence had halted the Princes Hwy upgrade at South Nowra.
Luckily for the frog, Ms Gash’s understanding of threatened species conservation has not been mirrored across the region.
Also that year, when the Village building company wanted to develop its Edgewood estate at Woonona, it had an issue with a green and golden bell frog community there.
With the aid of a Taronga Zoo breeding program they released thousands of bell frog tadpoles at purpose-built ponds nearby. Unfortunately, this community did not succeed, and is believed to have died out. It is possible that a small number of frogs survived and have retreated through the drier months, but this may be wishful thinking.
OEH programs in this region focus on two large populations – at Crookhaven and Meroo in the Shoalhaven. This is funded under the NSW Saving Our Species initiative.
The frog actually enjoys some disturbance of its habitat, Mr Wilmott said – drying out, then resoaking, of pools. “They’re sort of fussy and sort of not fussy,” he said. “They actually quite like some sorts of disturbances, but there’s others they don’t.”
This makes it difficult to design habitat projects – some that have been designed did not work; others, the frog has taken to despite seemingly hostile conditions.
“A lot of their strongholds these days are in man-made ponds and infrastructure,” Mr Wilmott said. “A lot of those natural areas where the frogs used to be, they have gone from, and they’re existing in Port Kembla and Kooragang Island off Newcastle, which are heavily industrialised, but that’s where they’re hanging on.”
Bluescope, whose steelworks have had a significant impact on frog-rich lagoons, has built a frog sanctuary, and Port Kembla remains one of the frog’s “strongholds”.
Many environmentalists may find it counterintuitive to suggest co-location between flora, fauna and heavy industry would be desirable. But the chemical runoff, along with sea salt, are understood to helping to protect the frog from chytrid Batrachochytrium dendrobatidis, a fungus that would otherwise finish off this unique creature.
“These populations that are persisting have either salt water nearby, or mine tailings, or industrial runoff,” Mr Willmot said.
“When they’re in water that has salt or these chemicals, it often kills the fungus, so they persist. Whereas in those natural areas that are more pristine – which they still exist at in some sites – there’s not that environmental fungus control.”
Chytrid (an introduced fungus, first found in the 1970s) has overtaken habitat loss as the greatest threat to this frog. It is also threatening other species, some of which have evolved to resist the fungus – including the stuttering frog and the giant barred frog.
“We haven’t really seen that in bell frogs yet, but there’s potential,” he said. “There’s a lot of work going on at the minute on disease and what can be done to mitigate it.”
BlueScope, whose steelworks have had a an impact on frog-rich lagoons, has built a frog sanctuary. And on Kooragang Island ponds are being built deeper so they take in more saline water to fight the fungus.
But while scientists are getting better at understanding its habitat, the frog has not yet become resilient. “The situation is not, I would say, improving,” Mr Wilmott said.”
Of course, if habitat had not been contracted by housing and industry, numbers might not be so critical that chytrid posed the final threat. But for now, this unique creature may have reached a spot it will occupy for years – threatened by disease in its shrunken ideal habitat, eking out an existence on the margins, on the edge.