Frogs are low on the food chain and provide food for many other animals - this makes them a very important part of Australian terrestrial ecosystems. The spotted marsh frog is one of the most common frogs within its range. The frog is usually found in association with water, and in dry periods shelters in cracks in the ground, usually under large rocks. Typically it is found in marshy country near grass-lined streams and ponds where it shelters under logs and stones. This species is very common and often the first frog to colonise new habitats.
Who’d be a frog in the suburbs? asks conservation biologist Joab Wilson from the ARC Centre of Excellence for Environmental Decisions (CEED) at RMIT.
Given that frogs around the world are suffering significant declines – some 30% of species are threatened with extinction – it’s a situation Australia needs to deal with better than we have till now, he says.
Our study produced a series of best- to worst-case climate and urbanisation scenarios for the suitability of pond habitat for the spotted marsh frog (Limnodynastes tasmaniensis) in the urban fringe of Melbourne..... They really are stuck between a rock and a hard place.
Wilson says that a vital finding of the study is that urban development poses a bigger risk to frog survival even than does climate change.
Scientists have found that under the dual impacts of climate change and high urban growth, the chances of frogs surviving in the 'burbs fall by more than 90 per cent. It's easy to use “climate change” as a scapegoat when the more real and vital threats come from directly from human impacts, driven by political-economic policies that promote population growth. Obviously, frogs can't live in concrete and bitumen!
Frogs found in Brisbane that might be affected but not necessarily wiped out included the green tree frog, graceful tree frog, stony creek frog, striped marsh frog, laughing tree frog and tusked frog.
The Conservation biologist from Melbourne's RMIT University said Frogs need to keep on the move, in order to find suitable wet areas as temperatures go up. In rural areas, there might be plenty of alternative habitats – but in fragmented landscapes, such as our cities, this isn't the case. Obviously, they end up hitting concrete pathways, roads, and hard, dry, urban surfaces with shrinking buffer zones, our "green wedges" .
A small urban concrete jungle is unlikely to have a frog in it while an established garden in an older style tradition suburb may provide a home for a number of common species. While climate change is a real threat, loss or degradation of habitat is a sure silver-bullet to extinction.
With high levels of development and the upper range of climatic predictions, pond sites were less than 1% likely to be occupied by the species.
Pond habitats in the Merri Creek (Melbourne) catchment are likely to become less suitable for amphibians under both climate and urbanisation scenarios. An increasingly warm and dry climate is likely to provide less standing water for species to be able to breed and for tadpoles to develop.
“Growth on the fringe
In June 2011, the Victorian Government released its final North Growth Corridor Plan, designating more land for urban development in the upper regions of Merri Creek catchment.
Three new high-density urban and industrial suburbs (Lockerbie, North Lockerbie and Merrifield West) are to be built in these areas, whereby major roads and development will encroach to within 40 m of the creek line. This is a grave blow for local wildlife, in
particular amphibians, as important patches of vegetation and floodplains will be built over. In addition, the development is likely to reduce water quality for amphibians further downstream.”
Frogs: Between a rock and a hard suburban place: Urban expansion, climate change and the decline of Melbourne’s frog habitat By Joab Wilson (EDG, RMIT)
Southern Hemisphere countries, such as Australia, haven't experienced such extremes in climate as experienced in the Northern Hemisphere Ice age, and many amphibian and reptile species have managed to survive in their current ranges. However, they have no evolutionary tools to cope with human expansion, urban sprawl and planning regimes that fail to consider a biological balance between species.
The Victorian Government is obligated under a joint federal and state agreement to develop strategies to protect threatened species including the Southern Brown Bandicoot, Growling Grass Frog and critically endangered Golden Sun Moth before final urban growth plans are released, but there's no protection for preventing impending threats to “common” species – the next threatened species. The now endangered Growling Grass Frog, one of the largest frog species in Australia, was previously widespread across Victoria.
Little attention is being given to the impacts of urban expansion, it could be we are ignoring the elephant in the room.....Given that current urban planning laws are the largest threat to amphibians such as the spotted marsh frog, maybe it’s time we started focussing more on the impact of urban expansion on our native wildlife – and finding ways to limit it, Wilson concludes .
(Spotted Marsh Frog - Wikimedia Commons)
It's doubtful that the welfare and future survival of frogs has a high priority in our States' planning departments, or in the portfolio of Minister for “Sustainable” Population, Tony Burke!
Australia has between 600,000 and 700,000 species, many of which are endemic. Human activities are reducing genetic, species and ecosystem biodiversity in Australia and population growth is a major driver, according to Sustainable Population Australia Inc. (SPA)
Much attention is being given to climate change threats to species, while so little is being given to the impacts of urban expansion on wildlife. The Flora and Fauna Guarantee Act in Victoria is supposed to protect threatened species, but when it comes to logging operations, changes to planning zones and our own population surge, these human activities are immune from this restrictive "red tape".