Ryan R. Witt, University of Newcastle; Chad T. Beranek, University of Newcastle; John Clulow, University of Newcastle; John Rodger, University of Newcastle; Lachlan G. Howell, University of Newcastle, and Robert Scanlon, University of Newcastle
Thousands of koalas may have died in fires burning through New South Wales but expert evidence to a state parliamentary inquiry on Monday said we are unlikely to ever know the real numbers.
Unprecedented fires have burned through millions of hectares of forest, including koala habitat and rainforests untouched by fire for thousands of years.
The devastation won’t stop once the fires are out. Koala populations that survive the fires could be cut off from each other, lowering their genetic diversity and threatening their long-term survival.
To protect Australia’s iconic koalas we need to start freezing their genetic material. With more investment in the fast-developing field of cryogenics, koala hospitals could start taking samples from their patients, creating a vital lifeline for the species as a whole.
This season, there is an above-average risk of serious fires across an extensive range of koala habitat on Australia’s east coast.
Experts at the NSW inquiry estimated about 2,000 koalas may have died in fires already this year, and the destruction of habitat means further population declines are inevitable. With areas not usually threatened by fires now at risk, we need new plans for future conservation.
Koalas are highly vulnerable to fire. The heat burns their paws and fur, and the superheated air can cause internal damage to their lungs. The canopy of eucalypt forests is their only refuge, but offers no protection during high-intensity bushfires.
Beyond this direct threat, when large numbers of koalas are killed or badly injured, the genetic diversity of their local populations shrinks.
Over the coming months, koalas will depend heavily on wildlife hospitals for rehabilitation and recovery after fires.
Small, fragmented groups of koalas living in habitat on the edge of urban areas, such as the coastal areas of Port Macquarie and Port Stephens, are particularly at risk.
If these events continue at the same rate – or, as predicted by climate modelling, become more intense and more frequent – we may lose sources of koala genetic diversity that cannot be replaced.
Sudden reductions in population size can cause genetic bottlenecks that lead to inbreeding. Eventually this reduces reproductive fitness and makes extinction more probable.
Take, for example, a koala population like that of Port Macquarie, between 1,000 and 2,000 individuals. We estimate that losing 350 koalas from this group would increase inbreeding by 20-50%. It would take five to ten years for the population to recover, assuming no further fires in that time.
While many volunteers and professionals do fantastic work to help koalas survive fire, we have no strategy for safeguarding genetic diversity and reducing the risk of inbreeding.
But we can take a lesson from botanical gardens, which routinely freeze genetic material for seed banks. Freezing koala sperm, eggs and embryos could offer a way to preserve genetic diversity ahead of further population crashes.
Artificial reproduction for koalas – and marsupials generally – is developing quickly. Scientists have used freshly collected sperm to artificially inseminate zoo koalas, which resulted in the birth of live young.
However, the technology does not yet exist to freeze, store and then use koala sex cells. Components of this process do exist, but there is no complete system for marsupials.
If that capacity existed, koala hospitals could easily and inexpensively begin collecting genetic samples from their patients.
Although NSW has invested significantly in koala conservation in recent years, we argue that future funding should also support applied research to make this technology a reality for not only koalas but other marsupials.
Koalas and many other native species are exceptionally unprotected in this new era of record-breaking fires. We need to start planning and investing in long-term conservation solutions and new research-based technologies that provide a last line of defence against the possibility of permanent extinction.
Ryan R. Witt, Conjoint Lecturer | Conservation Biology Research Group, University of Newcastle; Chad T. Beranek, PhD candidate, University of Newcastle; John Clulow, Associate Professor, University of Newcastle; John Rodger, Emeritus Professor, University of Newcastle & CEO FAUNA Research Alliance, University of Newcastle; Lachlan G. Howell, PhD Candidate | Conservation Biology Research Group, University of Newcastle, and Robert Scanlon, PhD Candidate in Restoration Ecology, University of Newcastle
Romane H. Cristescu, University of the Sunshine Coast; Anthony Schultz, University of the Sunshine Coast; Celine Frere, University of the Sunshine Coast; David Schoeman, University of the Sunshine Coast, and Kylie Scales, University of the Sunshine Coast
In a country like Australia – a wealthy, economically and politically stable nation with multiple environmental laws and comparatively effective governance – the public could be forgiven for assuming that environmental laws are effective in protecting threatened species.
But our new research, published recently in Animal Conservation, used koala-detecting dogs to find vulnerable koalas in places developers assumed they wouldn’t live. This highlights the flaws of environmental protections that prioritise efficiency over accuracy.
Every new infrastructure project must carry out an Environmental Impact Assessment (EIA) to see whether it will affect a threatened species. If this is the case, the logical next step is to try to avoid this by redesigning the project.
But this rarely happens in reality, as we saw recently for the endangered black-throated finch.
More often, when the EIA suggests an unavoidable impact the response is to identify mitigation and compensation measures, often in the form of “offsets”. These are swathes of comparable habitat assumed to “compensate” the impacted species for the habitat lost to the development.
To take koalas as an example, developers building houses might be required to buy and secure land to compensate for lost habitat. Or a new road might need fencing and underpasses to allow koalas safe passage across (or under) roads.
These steps are defined in environmental regulations, and depend on the results from the original EIA.
With koala numbers still declining, we investigated whether current survey guidelines for EIA were indeed adequate.
For an EIA to be effective, it is fundamental the environmental impact of a future development can be accurately anticipated and therefore appropriately managed. This relies, as a first step, on quantifying how the project will affect threatened species through ecological surveys of presence and extent of threatened species within the project’s footprint.
There are government guidelines to prescribe how these ecological surveys are performed. Every project has time and budget constraints, and therefore survey guidelines seek efficiency in accurately determining species’ presence.
As such, the Australian guidelines recommend focusing survey effort where there is the highest chance of finding a species of concern for the project. This sounded very logical – until we started testing the underlying assumptions.
We used a very accurate survey method – detection dogs – to locate koala droppings, and therefore identify koala habitat, in the entire footprint of proposed projects across Queensland. We did not target our efforts in areas we expected to be successful – therefore leaving out the bias of other surveys.
We found koalas did not always behave as one would expect. Targeting effort to certain areas, the “likely” koala habitat, to try increase efficiency risked missing koala hotspots.
In particular, the landscape koalas use is intensely modified by human activity. Koalas, like us, love living on the coast and in rich alluvial plains. That means we unexpectedly found them right in the middle of urban areas, along roads that – because they have the final remaining trees in dense agricultural landscapes – are now (counterintuitively) acting as corridors.
Assumptions about where koalas live can massively underestimate the impact of new infrastructure. In one case study, the habitat defined by recommended survey methods was about 50 times smaller than the size of the habitat actually affected.
If surveys miss or underestimate koala habitat while attempting to measure development impact, then we cannot expect to adequately avoid, mitigate or compensate the damage. If the first step fails, the rest of the process is fatally compromised. And this is bad news for koalas, among many other threatened species.
What is needed is a paradigm shift. In a world where humans have affected every ecosystem on Earth, we cannot focus on protecting only pristine, high-quality areas for our threatened species. We can no longer afford to rely on assumptions.
This might seem like a big, and therefore expensive, ask. Yet ecosystems are a common resource owned by all of us, and those who seek to exploit these commons should bear the cost of demonstrating they understand (and therefore can mitigate) their impact.
The alternative is to risk society having to shoulder the environmental debt, as we have seen with abandoned mines.
The burden of proof should squarely reside with the proponent of a project to study thoroughly the project impact.
This is where the issue lies – proponents of projects are under time and budget constraints that push them to look for efficiencies. In this tug of war, the main losers tend to be the threatened species. We argue that this cannot continue, because for many threatened species, there is no longer much room for mistakes.
The environmental regulations that define survey requirements need to prioritise accuracy over efficiency.
A review of Australian’s primary environmental law, the Environment Protection and Biodiversity Conservation Act is due to begin by October this year. We call on the government to use this opportunity to ensure threatened species are truly protected during development.
The authors would like to gratefully acknowledge the contribution of Dr David Dique and Russell L. Miller to this research and the two original papers this piece is based upon (feature paper and response).
Romane H. Cristescu, Posdoc in Ecology, University of the Sunshine Coast; Anthony Schultz, PhD Candidate, University of the Sunshine Coast; Celine Frere, Senior lecturer, University of the Sunshine Coast; David Schoeman, Professor of Global-Change Ecology, University of the Sunshine Coast, and Kylie Scales, Senior lecturer, University of the Sunshine Coast
Today the Australian Koala Foundation announced they believe “there are no more than 80,000 koalas in Australia”, making the species “functionally extinct”.
While this number is dramatically lower than the most recent academic estimates, there’s no doubt koala numbers in many places are in steep decline.
It’s hard to say exactly how many koalas are still remaining in Queensland, New South Wales, Victoria, South Australia and the Australian Capital Territory, but they are highly vulnerable to threats including deforestation, disease and the effects of climate change.
Once a koala population falls below a critical point it can no longer produce the next generation, leading to extinction.
The term “functionally extinct” can describe a few perilous situations. In one case, it can refer to a species whose population has declined to the point where it can no longer play a significant role in their ecosystem. For example, it has been used to describe dingoes in places where they have become so reduced they have a negligible influence on the species they prey on.
Dingoes are top predators, and therefore can play a significant role in some ecosystems. Our innocuous, leaf-eating koala cannot be considered a top predator.
For millions of years koalas have been a key part of the health of our eucalyptus forests by eating upper leaves, and on the forest floor, their droppings contribute to important nutrient recycling. Their known fossil records date back approximately 30 million years so they may have once been a food source for megafauna carnivores.
Functionally extinct can also describe a population that is no longer viable. For example in Southport, Queensland, native oyster reef beds are functionally extinct because more than 99% of the habitat has been lost and there are no individuals left to reproduce.
Finally, functionally extinct can refer to a small population that, although still breeding, is suffering from inbreeding that can threaten its future viability. We know that at least some koala populations in urban areas are suffering in this way, and genetic studies on the Koala Coast, located 20kms south-east of Brisbane, show that the population is suffering from reduced genetic variation. In South East Queensland, koalas in some areas have experienced catastrophic declines
We also know that koala populations in some inland regions of Queensland and New South Wales are affected by climate extremes such as severe droughts and heatwaves and have declined by as much as 80%.
Exhaustive multi-disciplinary koala research continues apace in an effort to find ways of protecting wild koala populations and ensuring that they remain viable now and into the future. Habitat loss, population dynamics, genetics, disease, diet and climate change are some key areas being studied.
Koala researchers are often asked “how many koalas are in the wild?” It’s a hard question to answer. Koalas are not stationary, are patchily distributed throughout an extremely wide range encompassing urban and rural areas in four states and one territory, and are usually difficult to see.
To determine whether each population of koalas scattered across eastern Australia is functionally extinct would require a gargantuan effort.
In 2016, in an attempt to determine population trends for the koala within the four states, a panel of 15 koala experts used a structured, four-step question format to estimate bioregional population sizes of koalas, and changes in those sizes.
The estimated percentage of koala population loss in Queensland, New South Wales, Victoria and South Australia was 53%, 26%, 14% and 3%, respectively. The estimated total number of koalas for Australia was 329,000 (within a range of 144,000–605,000), with an estimated average decline of 24% over the past three generations and the next three generations.
Since May 2012, koalas have been listed as vulnerable in Queensland, New South Wales and the Australian Capital Territory because populations in these regions have declined significantly or are at risk of doing so.
In the southern states of Victoria and South Australia, koala populations vary widely from abundant to low or locally extinct. Although not currently listed as vulnerable, these koalas are also experiencing a range of serious threats, including low genetic diversity.
To date, the present “vulnerable” listing has not achieved any known positive results for koala populations in Queensland and New South Wales. In fact, recent research invariably shows the opposite.
This is because the key threats to koalas remain, and are mostly increasing. The primary threat is habitat loss. Koala habitat (primarily eucalyptus woodlands and forests) continues to rapidly diminish, and unless it is protected, restored, and expanded, we will indeed see wild koala populations become “functionally extinct”. We know what comes after that.
Australia is one of the world’s most highly urbanised nations – 90% of Australians live in cities and towns, with development concentrated along the coast. This poses a major threat to native wildlife such as the koala, which can easily fall victim to urban development as our cities grow. Huge infrastructure projects are planned for Australian cities in the coming few years.
The need to house more people – the Australian population is projected to increase to as much as 49.2 million by 2066 – is driving ever more urban development, much of it concentrated in our biggest cities on the east coast. This is bad news for the koala population, unless the species’ needs are considered as part of planning approvals and the creation of urban green spaces. The good news is that koalas can learn to live the “green city life” as long as they are provided with enough suitable gum trees in urban green spaces.
Indeed, our newly published research, which analysed stress levels in wild koalas according to their habitat, reveals that koalas are the most stressed in rural and rural-urban fringe zones. This appears to be due to factors such as large bushfires, heatwave events, dog attacks, vehicle collision and human-led reduction of prime eucalyptus habitats. Koalas living in urban landscapes are less stressed as long as the city includes suitable green habitats.
In other words, wild animals including the koala can adapt to co-exist with human populations. Their ability to do so depends on us giving them the space, time and freedom to make that adaptation. This means ensuring they can carry out, without undue pressures, the biological and physiological functions on which their survival depends.
Wildlife species that lack access to suitable green habitats in cities are at higher risk of death and local extinction. Having to move between fragmented patches of habitat increases the risks. Land clearing and habitat destruction for infrastructure projects and other urban development are compounding the major threats to koalas, such as being hit by vehicles or attacked by dogs.
Animals cope with stressful situations in their lives through very basic life-history adjustments and ecological mechanisms. These include changes in physiology and behaviour in response to stresses in their environment.
We can help make the environment more suitable for wildlife species by ensuring their basic needs for food, water and shelter are met. If animals are deprived of any of these necessities, they will show signs of stress.
So by subjecting wildlife to extrinsic stressors such as habitat clearance, climate change and pollution we are making it even more difficult for these animals to manage stress in their daily lives.
Basically any unwanted change to an animal’s environment that prevents it from performing its basic life-history functions, such as foraging and social behaviour, will cause stress.
The koalas are telling us it’s a major problem when urban design is not green enough. Innovative solutions are needed!
Cities can do much more for wildlife conservation. Creating safe green spaces for wildlife is critical. Not just koalas but other wildlife such as birds, small mammals, reptiles and frogs can benefit immensely from urban green spaces.
Even in suburbs with plenty of green space, problems still arise because urban planning typically designs this space around access for human recreation and not for the wildlife that was living there before the housing development moved in.
Urban planning should always incorporate the planning of green spaces that are safe for wildlife. Providing wildlife crossings is part of the solution. Another important element is educational programs to alert drivers to the need to look out for koalas.
Measures like this can minimise impacts on wildlife that faces the many challenges of adjusting to city life.
News is out today that the entire genome of the koala has been sequenced. This means we now have a complete read-out of the genes and other DNA sequences of this iconic marsupial mammal.
Knowing the full set of koala genes deepens our knowledge of koalas (and other Australian mammals) in many ways. Now we can understand how koalas manage to survive on such a toxic diet of gum leaves. Now we can follow the fortunes of historic koala populations and make good decisions about how to keep remaining koala populations healthy. Now we have a new point of comparison that we can use to understand how the mammal genome evolved.
This is important for science – but also economically. Koalas are incredibly well loved, with their baby-faces, shiny noses and big fluffy ears. Millions of visitors line up each year to spot them snoozing in gum trees – indeed, they are worth A$3.2 billion in tourist dollars.
Koalas are listed as a vulnerable species in some parts of Australia, affected by habitat destruction, disease and other stresses.
Koala DNA was sequenced with new “long-read” technology that delivers a complete and well-assembled genome. As far as quality of the read-out goes, it’s as good as the human genome, with continuous sequences now known over huge (almost chromosome-scale) spans. New technology enabled us to achieve this at a tiny fraction of the $2.7 billion it cost to sequence the first human.
The obtained koala genome sequence is much better quality than that for other sequenced marsupials – opossum, tammar wallaby and Tasmanian devil – and will really help us to assemble and compare genomes from all marsupials.
The koala has a genome a bit bigger than that of humans, with 3.5 billion DNA base-pairs. This amounts to about a metre of DNA, which is divided and packaged into eight large bits that we recognise as chromosomes.
An animal has a set of chromosomes from mother and a set from father, so koalas have 16 large chromosomes in each cell. This is similar to other marsupials; as a group they seem to have a low chromosome number and a very stable genome arrangement. In placental mammals the number and arrangement of chromosomes is much more varied: for example, humans have 46, and rhinos 82 chromosomes.
New findings from the koala genome help us to understand how mammal genomes evolved and how they work.
A lot (sometimes more than 50%) of animal genomes seem to be “junk DNA” – these are repeated sequences, many deriving from ancient viral infections. The koala, uniquely, seems to be in the middle of one such invasion. A DNA sequence derived from a retrovirus is present in different numbers and sites in different koala populations, testifying to its recent movement and amplification. This helps us learn how the genomes of humans and other mammals got so puffed up with junk DNA.
Like the human genome, the koala genome contains about 26,000 genes. These are stretches of DNA that code for or control proteins. Indeed, most koala genes are present in humans and other mammals – these are the same genes doing the same basic jobs in different animals.
So why is it important to sequence different species if their genomes are so similar? Well, it’s the special genes that have evolved to adapt the koala to its unique lifestyle that give us new and valuable information.
How koalas exist on an exclusive low-calorie and toxin-laced diet of eucalyptus leaves has been somewhat of a science mystery.
The genome provides answers. The koala has multiplied a family of genes that code for enzymes (members of the cytochrome P450 family) that break down the toxins of gum leaves. Evolution of these additional gene copies has enabled the koala to outstrip its competition, even at the cost of sleeping most of the day.
The genome also gives us clues to the koala’s picky eating habits. The koala genome contains many additional copies of genes that enable them to taste and avoid bitter flavours and even to “smell” water and choose juicy leaves (they don’t drink water).
The genome also gives us new information about how koalas develop. Like other marsupials, they are born about the size of a pea, and complete most of their growth and differentiation in the pouch. Developing koalas are nurtured by milk with a complex composition that changes with the stage of development.
Managing koala populations is very fraught, and there has long been a need for a holistic, scientifically-grounded approach to koala conservation.
Today’s koalas are the “last stand” of the marsupial family Phascolarctidae – and the koala genome contains new information about this evolutionary history. It also tells us that koala populations peaked about 100,000 years ago, then plunged to about 10% of their numbers 30-40,000 years ago, at the same time that the megafauna became extinct. This population was fairly stable until European settlement, when it plunged again to its present numbers (about 300,000).
Koalas once occupied a swathe of timbered habitat from Queensland to South Australia; now, only fragmented populations survive in the south. These are intensively managed, and small numbers of koalas are translocated to other sites, producing dangerously inbred populations. Bizarrely, one of the greatest problems is overbreeding in isolated populations – for example, on South Australia’s Kangaroo Island – which leads to animals eating themselves out of house and home.
The enemies of koalas in the north are habitat destruction and fragmentation by urbanisation and climate change.
The koala genome paper reports sequence comparisons of different populations and identifies barriers to gene flow. With the information from the koala genome, we can now monitor genetic diversity in the surviving populations, and maximise gene flow between connected populations.
Maintaining genetic diversity is important because different animals can mount different responses to environmental threats and diseases such as chlamydia, a bacteria that affects koala reproduction and eye health.
The koala genome provides us with information about the immune genes of the koala, and the changes in activity of these genes in infected animals. This will help us understand the different responses of animals, vital for developing vaccines and treatments.
The koala genome also identifies powerful anti-bacterials in milk that protect the baby koala from disease – and may provide humans with the next generation of antibiotics.
So sequencing the koala genome is good for science and good for koalas, an iconic species at the top of the tree for conservation efforts.