‘Like trying to find the door in a dark room while hearing your relatives scream for help’: Tasmania’s whale stranding tragedy explained


Olaf Meynecke, Griffith University

A desperate rescue effort is underway after hundreds of long-finned pilot whales (Globicephala melas) became stranded in Macquarie Harbour on Tasmania’s west coast.

Yesterday, more than 250 pilot whales were reported to have stranded, with one-third presumed dead. And this morning, rescuers found another 200 pilot whales stranded up to ten kilometres away from the first group — most are likely dead.

This brings the total number of stranded pilot whales in Tasmania to more than 450, and it’s believed to be the biggest ever recorded in the state. The Greens are calling on federal Environment Minister Sussan Ley to launch a national response.

The rescue mission aims to refloat the pilot whales that appear to still be in reasonable health. But their behaviour hampers rescue efforts: many pilot whales re-strand themselves to be with their family. This event likely means a number of generations of the local population will be lost.




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Do whales attempt suicide?


How did they become stranded?

Despite its name, the long-finned pilot whale is actually a large oceanic dolphin. They cover vast areas of the Southern (Antarctic) Ocean, reaching between four and six metres in length and weighing up to one tonne.

They are well adapted to deeper oceans where they hunt for various species of squid in depths of between 600-1,000m, using echolocation to find their prey. Echolocation is a way of using sound to navigate in complete darkness.

They generally spend most of their lives offshore and it’s not well understood what conditions drive them close to shore, and to enter shallow embayments.

Some theories suggest food shortages are to blame, or changes in electromagnetic fields that disorient them. They may also be following a sick or distressed pod leader. And in some past cases strandings were related back to active sonar from ships and naval sonar interrupting their echolocation.




Read more:
What causes whale mass strandings?


But once in shallow waters, it’s difficult to swim back out. As these whales mostly navigate with echolocation it’s not possible for them to use sonar effectively in shallow and muddy embayments.

It’s extremely distressing for the whales, a lot like trying to find the door in a dark room while hearing your relatives scream for help.

In fact, the stress is what many die from in the end. Other causes of death are overheating from sun exposure and drowning if they can’t move their bodies up to breach the surface in shallow water.

The rescue efforts

There are a number of strategies to refloat whales. In Macquarie Harbour, rescuers are using slings to tow the whales to deeper water, before releasing them.

Other options include multiple people pushing them off the beach during high tide into deeper water.

In this case, albeit potentially dangerous for the helpers, people power can make a big difference. After all, time is of immense importance for success, and to stop more whales beaching.

However, chances of survival plummet with long exposure to sun and extended periods of stress. What’s more, Macquarie Harbour is relatively remote and difficult to access, further complicating rescue efforts.

Dying together

But the biggest obstacle rescuers face is the whales’ social bonding. Long-finned pilot whales are highly intelligent and live in strong social units.

So when dealing with mass strandings, it’s important to realise the emotions and bonding between the whales are very likely beyond what humans can feel. One well-documented example of their emotional depth is the pilot whale seen carrying its dead calf for many days.

Mother pilot whale grieves over her dead calf.

This makes the stranding process extremely complex, as it unfolds over several hours to several days — the whales don’t all strand at the same time.

We know from killer whales, which also have strong social bonding, that if a close member of the group strands, others will attempt to join to die together.




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We need to understand the culture of whales so we can save them


The situation for pilot whale pods can be similar, but more complex as a result of having much larger pods. Pilot whale pods have multiple sub-units, which can consist of friends as well as family and they don’t have to be genetically related.

Social units get mixed up when they’re in shallow bays. This means individuals can become disconnected from their social units before the actual stranding occurs, causing stress and confusion prior the beaching.

Fewer pilot whales in the gene pool

There are an estimated 200,000 long-finned pilot whales in the Southern Ocean and Antarctica, but mass strandings like this can have a profound impact on sub-populations.

In Tasmania alone, 1,568 long-finned pilot whales have stranded between 1990 and 2008 in 30 stranding events.

Many similar sad events occured in New Zealand: hundreds of long-finned pilot whales stranded in 2018 and 2017, and the majority died.

To make matters worse, studies suggest the long-finned pilot whales in the Southeastern Pacific have low genetic diversity. There are similarities between this species found in Chile and New Zealand, but with surprisingly distinct differences between New Zealand and Tasmania.

Considering they can live up to 50 years and the fact only few survive when multiple generations strand, such events not only destroy entire generations but also remove them from the gene pool.

This puts local populations at further risk. Inbreeding is one consequence, but the biggest problem is their decreasing general fitness and ability to adapt to changes.

How to help

In the past, significant numbers of stranded whales have been successfully released, making it worth the effort. For example, in one of largest mass strandings in New Zealand in 2017, volunteers helped about 100 whales refloat, and made a human chain to try to stop them restranding.




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Still, such events are likely to be more frequent in the future due to changing ocean conditions and increasing human activity such a noise pollution, commercial squid fisheries and deep sea mining.

Climate change shifts ocean currents as sea temperature rises. And with this, squid availability will change. A lack of food offshore can cause stress and drive them closer to shore.

We can help the whales not only by actively supporting rescue organisations such as ORRCA, but also by helping reduce carbon emissions, foster sustainable fisheries, reduce plastic pollution and advocate for marine sanctuaries.The Conversation

Olaf Meynecke, Research Fellow in Marine Science, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Photos from the field: capturing the grandeur and heartbreak of Tasmania’s giant trees



Steve Pearce/The Tree Projects, Author provided

Jennifer Sanger, University of Tasmania

Environmental scientists see flora, fauna and phenomena the rest of us rarely do. In this new series, we’ve invited them to share their unique photos from the field.


Tasmania’s native forests are home to some of the tallest, most beautiful trees in the world. They provide a habitat for many species, from black cockatoos and masked owls to the critically endangered swift parrot.

But these old, giant trees are being logged at alarming rates, despite their enormous ecological and heritage value (and untapped tourism potential). Many were also destroyed in Tasmania’s early 2019 fires.




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Former Greens leader Bob Brown recently launched a legal challenge to Tasmania’s native forest logging. And this year, Forestry Watch, a small group of citizen scientists, found five giant trees measuring more than five metres in diameter inside logging coupes. “Coupes” are areas of forest chopped down in one logging operation.

These trees are too important to be destroyed in the name of the forestry industry. This is why my husband Steve Pearce and I climb, explore and photograph these trees: to raise awareness and foster appreciation for the forests and their magnificent giants.

Climbing trees is not just for the young, but for the young at heart. Kevin is in his early 70’s and helps us with measuring giant trees.
Steve Pearce/The Tree Projects, Author provided

What makes these trees so special?

Eualypytus regnans, known more commonly as Mountain Ash or Swamp Gum, can grow to 100 metres tall and live for more than 500 years. For a long time this species held the record as the tallest flowering tree. But last year, a 100.8 m tall Yellow Meranti (Shorea faguetiana) in Borneo, claimed the title — surpassing our tallest Eucalypt, named Centrioun, by a mere 30 centimetres.

Centrioun still holds the record as the tallest tree in the southern hemisphere. But five species of Eucalypt also grow above 85 m tall, with many ranking among some of the tallest trees in the world.

It’s not only their height that make these trees special, they’re also the most carbon dense forests in the world, with a single hectare storing more than 1,867 tonnes of carbon.




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Our giant trees and old growth forests provide a myriad of ecological services such as water supply, climate abatement and habitat for threatened species. A 2017 study from the Central Highlands forests in Victoria has shown they’re worth A$310 million for water supply, A$260 million for tourism and A$49 million for carbon storage.

This significantly dwarfs the A$12 million comparison for native forest timber production in the region.

Chopped wood in a logging coupe.
Chopping down old growth trees doesn’t make economic sense.
Steve Pearce/The Tree Projects, Author provided

Tasmania’s Big Tree Register

Logging organisation Sustainable Timber Tasmania’s giant tree policy recognises the national and international significance of giant trees. To qualify for protection, trees must be at least 85 m tall or at least an estimated 280 cubic metres in stem volume.




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While it’s a good place to start, this policy fails to consider the next generation of big, or truly exceptional trees that don’t quite reach these lofty heights.

That’s why we’ve created Tasmania’s Big Tree Register, an open-source public record of the location and measurements of more than 200 trees to help adventurers and tree-admirers locate and experience these giants for themselves. And, we hope, to protect them.

Last month, three giant trees measuring more than 5 m in diameter were added to the register. But these newly discovered trees are located in coupe TN034G, which is scheduled to be logged this year.

Logging is a very poor economic use for our forests. Native forest logging in Tasmania has struggled to make a profit due to declining demand for non-Forest Stewardship Council certified timber, which Sustainable Timber Tasmania recently failed. In fact, Sustainable Timber Tasmania sustained an eye watering cash loss of A$454 million over 20 years from 1997 to 2017.




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The following photos can help show why these trees, as one of the great wonders of the world, should be embraced as an important part of our environmental heritage, not turned to wood chips.

A portrait of an entire tree captured. Its canopy breaches the clouds.

Steve Pearce/The Tree Projects, Author provided

It’s not often you get to see the entirety of a tree in a single photo. This tree above is named Gandalf’s Staff and is a Eucalyptus regnans, measuring 84 m tall.

While Mountain Ash is the tallest species, others in Tasmania’s forests are also breathtakingly huge, such as the Tasmanian blue gum (Eucalyptus globulus) at 92 m, Manna gum (Eucalyptus viminalis) at 91 m, Alpine ash (Eucalyptus delegatensis) at 88 m and the Messmate Stringybark (Eucalyptus obliqua) at 86 m.

A woman appears tiny standing against an enormous felled tree.

Steve Pearce/The Tree Projects, Author provided

This giant tree, pictured above, was a Messmate Stringybark that was felled in coupe, but was left behind for unknown reasons. Its diameter is 4.4 metres. Other giant trees like this were cut down in this coupe, many of which provided excellent nesting habitat for the critically endangered swift parrot.

Nine people sit across the trunk of an enormous tree.
The citizen science group Forestry Watch helps search for and measure giant trees in Tasmania.
Steve Pearce/The Tree Projects, Author provided

Old-growth forests dominated by giant trees are excellent at storing large amounts of carbon. Large trees continue to grow over their lifetime and absorb more carbon than younger trees.

A man wraps a measuring tape around a huge tree trunk, covered in moss.

Steve Pearce/The Tree Projects, Author provided

The tree in the photo above is called Obolus, from Greek mythology, with a diameter of 5.1 m. Names are generally given to trees by the person who first records them, and usually reflect the characteristics of the tree or tie in with certain themes.

For example, several trees in a valley are all named after Lord of the Rings characters, such as Gandalf’s Staff (pictured above), Fangorn and Morannon.

The tops of the giant tree canopies are higher than the clouds.

Steve Pearce/The Tree Projects, Author provided

Giant trees are typically associated with Californian Redwoods or the Giant Sequoias in the US, where tall tree tourism is huge industry. The estimated revenue in 2012 from just four Coastal Redwood reserves is A$58 million dollars per year, providing more than 500 jobs to the local communities.

Few Australians are aware of our own impressive trees. We could easily boost tourism to regional communities in Tasmania if the money was invested into tall tree infrastructure.The Conversation

Jennifer Sanger, Research Associate, University of Tasmania

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Tasmanian tiger was hunted to extinction as a ‘large predator’ – but it was only half as heavy as we thought



Smithsonian Institution/colourised by D.S. Rovinsky

Douglass Rovinsky, Monash University; Alistair Evans, Monash University, and Justin W. Adams, Monash University

Until it was hunted to extinction, the thylacine – also known as the Tasmanian tiger or Tasmanian wolf – was the world’s largest marsupial predator. However, our new research shows it was in fact only about half as large as previously thought. So perhaps it wasn’t such a big bad wolf after all.

Although the thylacine is widely known as an example of human-caused extinction, there is a lot we still don’t know about this fascinating animal. This even includes one of the most basic details: how much did the thylacine weigh?

An animal’s body mass is one of the most fundamental aspects of its biology. It affects nearly every facet of its biology, from biochemical and metabolic processes, reproduction, growth, and development, through to where the animal can live and how it moves.

For meat-eating predators, body mass also determines what the animal eats – or more specifically, how much it has to eat at each meal.

Catching and eating other animals is hard work, so a predator has to weigh the costs carefully against the benefits. Small predators have low hunting costs – moving around, hunting, and killing small prey doesn’t cost much energy, so they can afford to nibble on small animals here and there. But for bigger predators, the stakes are higher.

Almost all large predators – those weighing at least 21  kilograms – focus their efforts on prey at least half their own body size, getting more bang for the buck. In contrast, small predators below 14.5 kg almost always catch prey much smaller than half their own size. Those in between typically take prey less than half their size, but sometimes switch to a larger meal if some easy prey is there for the taking – or if the predator is getting desperate.

The mismeasure of the thylacine

Scan of article from Launceston Examiner
The March 14, 1868 edition of the Launceston Examiner featured tales of a ‘hyena’ that managed to kill 25 sheep.
trove.nla.gov.au

Few accurately recorded weights exist for thylacines – only four, in fact. This lack of information has made estimating their average size difficult. The most commonly used average body mass is 29.5kg, based on 19th-century newspaper accounts.

This suggests the thylacine would probably have taken relatively large prey such as wallabies, kangaroos and perhaps sheep. However, studies of thylacine skulls suggest they didn’t have strong enough skulls to capture and kill large prey, and that they would have hunted smaller animals instead.

This presented a problem: if the thylacine was as big as we thought, it shouldn’t be able to live solely on small prey. But what if we’ve had the weight wrong the whole time?




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Weighing an extinct animal

Man taking a scan of a stuffed thylacine
Ben Myers of Thinglab scans a Museums Victoria thylacine.
CREDIT, Author provided

Our new research, published today in Proceedings of the Royal Society B, addresses this weighty issue. Our team travelled throughout the world to museums in Australia, the United States, the United Kingdom and Europe, and 3D-scanned 93 thylacines, including whole mounted skeletons, taxidermy mounts, and the only whole-body ethanol-preserved thylacine in the world, in Sweden.

Based on these scans, we created new equations to estimate a thylacine’s mass, based on how thick their limbs were – because their legs would have had to support their entire weight.

We also compared the results of these equations with a new method of digitally weighing 3D specimens. Based on a 3D scan of a mounted skeleton, we digitally “filled in the spaces” to estimate how much soft tissue would have been present, and then used our new formula to calculate how much this would weigh. Taxidermy mounts were easier as there was no need to infer the amount of soft tissue. The most artistic member of our team digitally sculpted lifelike thylacines around the scanned skeletons, and we weighed them, too.

Building and weighing a thylacine. Scanned skeletons (lop left) were surrounded by digital ‘convex hulls’ (top right), which then had their volume and mass calculated. The skeletons were then used in digitally sculpting lifelife models (bottom left), each with their own unique stripes (bottom right).
Rovinsky et al.

Our calculations unanimously told a very different story from the 19th-century periodicals, and from the commonly used estimate. The average thylacine weighed only about 16.7 kg – not 29.5 kg.




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Tall tales on the tiger trail

This means the previous estimate, based on taking 19th-century periodicals at face value, was nearly 80% too large. Looking back at those old newspaper reports, many of them in retrospect have the hallmarks of “tall tales”, told to make a captured thylacine seem bigger, more impressive and more dangerous.

It was based on this suspected danger that the thylacine was hunted and trapped to extinction, with private bounties already placed on them by 1840, and government-sponsored extermination by the 1880s.

Graphic showing the size of thylacines relative to a woman
Thylacines were much smaller in stature than humans or grey wolves.
Rovinsky et al., Author provided

The thylacine was much smaller than previously thought, and this aligns with the smaller prey size suggested by the earlier studies. Predators below 21 kg – in which we should now include the thylacine – all tend to hunt prey smaller than half their size. The “Tasmanian wolf” probably wasn’t such a danger to Tasmanian farmers’ sheep after all.

By rewriting this fundamental aspect of their biology, we are closer to understanding the role of the thylacine in the ecosystem – and to seeing exactly what was lost when we deliberately hunted it to extinction.The Conversation

Douglass Rovinsky, PhD Candidate, Monash University; Alistair Evans, Associate Professor, Monash University, and Justin W. Adams, Senior Lecturer, Department of Anatomy and Developmental Biology, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Meet Moss, the detection dog helping Tassie devils find love



Zoos Victoria, Author provided

La Toya Jamieson, La Trobe University and Marissa Parrott, University of Melbourne

Moss bounds happily through the bush showing the usual exuberance of a young labrador. Despite this looking like play, he is on a serious mission to help fight the extinction of some of our most critically endangered species.

Moss is a detection dog in training. Unlike other detection dogs, who might sniff out drugs or explosives, he’ll be finding some of Victoria’s smallest, best camouflaged and most elusive animals.




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These dogs use their exceptional olfactory senses to locate everything from koalas high in the trees, desert tortoises burrowed deep under soil and even whales — often more effectively than any human team could aspire to.

What makes Moss unique, however, is he’ll not only find endangered species in the wild, but will also be part of a larger team helping endangered species breed in captivity. These dogs will be the first in the world to do this, starting with a ground-breaking trial with Tasmanian devils.

Moss will eventually help find the tiny, cryptic Baw Baw Frog in the wild.

Why Moss needed a job

Wildlife detection dogs are a very rare type of dog — they are highly motivated, engaged and energetic, but also incredibly reliable and safe around the smallest of creatures.

And Moss is the first dog to join Zoos Victoria’s Detection Dog squad, a permanent group of highly trained dogs that will live at Healesville Sanctuary.




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Moss was adopted at 14 months old, after he somewhat “failed” at being a family pet. He is a hurricane of energy with an intelligent and playful mind. He’s thriving with a job to keep him occupied and new challenges for his busy brain.

One sign he was perfect for this program was his indifference to the free range chickens at his foster home. For obvious reasons, a dog who likes chasing chickens wouldn’t be a good candidate for protecting some of Australia’s rarest feathered treasures.

Moss will also help monitor incredibly well camouflaged plains-wanderers, which are nearly impossible to spot in the day.

Currently Moss is learning crucial foundational skills, and getting plenty of exposure to different environments. Equally important, he is developing a deep bond and trust with his handlers.

The detection dog-handler bond is crucial not only for his happiness, but also for working success and longevity. Research from 2018 found a strong bond between a handler and their dog dramatically improved the dog’s detection results and reduced signs of stress.

The Tasmanian devil’s advocate

Healesville Sanctuary breeds endangered Tasmanian Devils every year as part of an insurance program to support conservation and research. This program is crucial to help protect the devil following an estimated 80% decline in the wild due to a horrific transmissible cancer, Devil Facial Tumour Disease.




Read more:
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But managing a predator that’s shy, nocturnal and prefers to be left alone can be tricky.

Wildlife, including Tasmanian devils, need a hands-off approach where possible, so they can maintain natural behaviours and thrive in their environment.

Tasmanian devils prefer to be left alone.
Healesville Sanctuary, Author provided

In the wild, devils leave scats (faeces) at communal latrine sites and use scent for communication. Male devils can tell a female is ready to mate by smelling her scat. And we think dogs could be trained to detect this, too.

We aim to train dogs to detect an odour profile in the collected scat of female devils coming into their receptive (oestrus) periods, so we can introduce females and suitable males to breed at the optimal time. The odour profile will be further verified via laboratory analyses of hormones in the scats.




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The project will also explore whether dogs can detect pregnancy and lactation in the devils.

Currently, the best way to determine if a female has young is to look in her pouch, but our preference is to remain at a distance during this important time while females settle into being new mums.

Moss with his trainer, Latoya. Moss is a ball of energy and thrives in the challenging environment of conservation detection.
Healesville Sanctuary, Author provided

If the dogs are able to smell a scat sample (while never coming into contact with the devil) and identify that a female is lactating with small joeys in her pouch, we can support her – for example, by increasing her food – while keeping a comfortable distance.

A new partnership in conservation

The results from this devil breeding research could offer innovative new options for endangered species breeding programs around the world.

Wildlife detection in the field means we can more accurately monitor some of our most critically endangered species, and quickly assess the impact of catastrophic events such as bushfires.




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Detection dogs are the perfect intermediary between people and wildlife — they can sniff out what we can’t and communicate with us as a team.

And over the next few years, the Detection Dog Squad will expand to five full-time canines. They will all be selected based on their personalities rather than specific breeds, so will likely come in all shapes and sizes.

Dogs may yet go from being man’s best friend to the devil’s best friend and beyond, all starting with a happy labrador named Moss.


This article is co-authored by Naomi Hodgens, Wildlife Detection Dog Officer at Zoos Victoria, and Dr Kim Miller, Life Sciences Manager, Conservation and Research, at Healesville Sanctuary, Zoos Victoria.The Conversation

La Toya Jamieson, Wildlife Detection Dog Specialist, La Trobe University and Marissa Parrott, Reproductive Biologist, Wildlife Conservation & Science, Zoos Victoria, and Honorary Research Associate, BioSciences, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

We developed tools to study cancer in Tasmanian devils. They could help fight disease in humans



Shutterstock

Andrew S. Flies, University of Tasmania; Amanda L. Patchett, University of Tasmania; Bruce Lyons, University of Tasmania, and Greg Woods, University of Tasmania

Emerging infectious diseases, including COVID-19, usually come from non-human animals. However our understanding of most animals’ immune systems is sadly lacking as there’s a shortfall in research tools for species other than humans and mice.

Our research published today in Science Advances details cutting edge immunology tools we developed to understand cancer in Tasmanian devils. Importantly, these tools can be rapidly modified for use on any animal species.

Our work will help future wildlife conservation efforts, as well as preparedness against potential new diseases in humans.

The fall of the devil

Tasmanian devil populations have undergone a steep decline in recent decades, due to a lethal cancer called devil facial tumour disease (DFTD) first detected in 1996.

A decade after it was discovered, genetic analysis revealed DFT cells are transmitted between devils, usually when they bite each other during mating. A second type of transmissible devil facial tumour (DFT2) was detected in 2014, suggesting devils are prone to developing contagious cancers.

A Tasmanian devil with devil facial tumour disease.
Save the Tasmanian Devil Program

In 2016, researchers reported some wild devils had natural immune responses against DFT1 cancers. A year later an experimental vaccine for the original devil facial tumour (DFT1) was tested in devils artificially inoculated with cancer cells.

While the vaccine didn’t protect them, in some cases subsequent treatments were able to induce tumour regression.

But despite the promising results, and other good news from the field, DFT1 continues to suppress devil populations across most of Tasmania. And DFT2 poses an additional threat.




Read more:
Deadly disease can ‘hide’ from a Tasmanian devil’s immune system


Following a blueprint requires tools

In humans, there has been incredible progress in treatments targeting protein that regulate our immune system. These treatments work by stimulating the immune system to kill cancer cells.

Our team’s analyses of devil DNA showed these immune genes are also present in devils, meaning we may be able to develop similar treatments to stimulate the devil immune system.

But studying the DNA blueprint for devils takes us only so far. To build a strong house, you need to understand the blueprint and have the right tools. Proteins are the building blocks of life. So to build effective treatments and vaccines for devils we have to study the proteins in their immune system.

Until recently, there were few research tools available for this. And this problem was all too familiar to researchers studying immunology and disease in species other than humans, mice or rats.

Into the FAST lane

You could build a house with just a saw, hammer and nails – but a better and faster build requires a larger, more versatile toolbox.

In our new research, we’ve added more than a dozen tools to the toolbox for understanding tumours in Tasmanian devils. These are Fluorescent Adaptable Simple Theranostic proteins – or simply, FAST proteins.

The term “theranostic” merges therapeutic and diagnostic. FAST proteins can be used as a therapeutic drug to treat a disease, or as a diagnostic tool to determine its cause and better understand it.

A key feature of FAST proteins is they can be tagged with a fluorescent protein marker, and can be released from the cells that we engineered in the lab to make them.

This way, we can collect and observe how the proteins attach and interact with other proteins without needing to add a tag later in the process.

To understand this, imagine trying to use a tiny key in a tiny lock in the dark. It would be difficult, but much easier if both were tagged with a coloured light. In the context of the immune system, it’s easier to understand what we need to turn on or off if we can see where the proteins are.

By mapping how proteins within the devil’s immune system interact, we can find better ways to stimulate the immune system.

An overview of the FAST protein system. Fluorescent proteins and immune system proteins from different species can be rapidly swapped to make new FAST proteins.
Andrew S. Flies/WildImmunity

The FAST system is also adaptable, meaning new targets can be cut-and-pasted into the system as they’re identified, like changing the bits on a drill. Therefore, it’s useful for studying the immune systems of other animals too, including humans.

Also, the system is simple enough that most people with basic cell culture and molecular biology experience could use it.




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Needle in a haystack

Cancer cells in humans and animals can travel via the bloodstream to spread, or “metastasise”, throughout the body. Identifying single tumour cells in blood can shed light on how cancer invades devils’ organs and kills them.

Using FAST tools, we discovered CD200 – a protein that inhibits anti-cancer responses in humans – is highly expressed in devils. With FAST tools, we were able to mix DFT2 cancer cells into devil blood and pick them out, despite there being about one cancer cell for every 1,000 blood cells.

CD200 is a powerful “off switch” for the immune system, so identifying this off switch allows us it can help us produce a vaccine that disables the switch.

A devil facial tumour 2 (DFT2) cell, with the cell nucleus shown in blue.
Andrew S. Flies/WildImmunity

By rapidly sifting out the best ways to stimulate the devil’s immune system, FAST tools are accelerating our research into developing a preventative vaccine to protect devils from DFT.

Why study animal immune systems?

COVID-19 has once again brought emerging infectious diseases onto the global stage. The ability to rapidly develop immunology tools for new species means we can jump into action when a new virus jumps into humans.

Additionally, species are going extinct at an alarming rate, and wildlife disease is increasingly threatening conservation efforts.

Understanding how the immune systems of other animals fight diseases could provide a blueprint for developing vaccines and therapeutics to help them.The Conversation

Andrew S. Flies, Senior Research Fellow in Immunology, University of Tasmania; Amanda L. Patchett, , University of Tasmania; Bruce Lyons, , University of Tasmania, and Greg Woods, Professional Research Fellow, University of Tasmania

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Sexual aggression key to spread of deadly tumours in Tasmanian devils



Both male and female Tasmanian devils can become very violent during sexual interactions.
Shutterstock/PARFENOV

David Hamilton, University of Tasmania; Elissa Cameron, University of Tasmania; Menna Elizabeth Jones, University of Tasmania, and Rodrigo Hamede, University of Tasmania

Tasmanian devils have a reputation as a fearsome animal – most of the time this is undeserved. When it comes to the mating season, however, it’s a fair judgement. Between February and April, mating can be incredibly aggressive, with male and female devils prone to biting one another both during and after the act.

That could be deadly for the devils, according to new research published online in the journal Behavioral Ecology.

Unfortunately, biting drives the spread of devil facial tumour disease (DFTD) a transmissible cancer that has been afflicting the species since the mid-1990s.




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Survival of the fittest? Perhaps not if you’re a Tasmanian devil


DFTD is highly unusual for a cancer because it can transfer between individual devils and grow in its new host.

The fact that devils regularly bite one another around the mouth means tumour cells can easily transfer from an infected devil to an open wound on a healthy devil. This makes the buildup of wounds in devils extremely important to our understanding of this disease.

When devils mate

In our study, we examined the accumulation of bite wounds in a population of wild devils in northwest Tasmania.

We found males were much more likely than females to pick up high numbers of bite wounds. But these wounds appear to be related to the amount of time males spent in mating season interactions with females, as opposed to fights with other males (as we had previously thought).

In the mating season, after male devils have mated with females, they spend an extended period either confining the female in a den, or closely following her to make sure other males are unable to mate with her.

During our study we found this behaviour could go on for up to two weeks in the wild. The process is known as “mate guarding” and is relatively common in the animal kingdom.

We found the longer males spent engaging in mate guarding behaviour, the more bite wounds they received. This would seem to put successful males, who mate with a high number of females, in the firing line when it comes to acquiring DFTD.

But no pattern of sex bias in DFTD prevalence has ever been observed in the wild.

So how does this fit with our study on the increased vulnerability in males?

A Tasmanian devil with the Devil Facial Tumour Disease.
Menna Jones/PLOS ONE, CC BY

Disease transfer

A crucial unknown in the DFTD transmission process involves directionality – which way the deadly disease is passed on by a devil. There are two possibilities:

  1. an infected devil bites an uninfected animal, transferring tumour cells (from its teeth or saliva) directly into the wound it causes

  2. an uninfected devil bites into tumours on an infected animal, and cells transfer into an open wound inside the biter’s mouth.

The reality is likely to involve a combination of the two.

Our results indicate that most disease transmission occurs during extended mating season interactions, when females appear to be causing high numbers of wounds to their mates.

If DFTD can transfer in either direction during these encounters, then both the males receiving the wounds and the females causing them would be equally at risk of acquiring the disease.

Future of the devil

We have highlighted mating season encounters between the sexes as crucial transmission points for the spread of DFTD. The behaviour of male devils appears to be driving patterns that support transmission of the disease.

This information is important for potential disease management options, as it pinpoints males in good condition – who are likely to be reproductively successful – as targets for management interventions, such as vaccinations.

Most importantly, these results add one more piece to the puzzle of rapid evolution in the Tasmanian devil, in response to the strong evolutionary pressure DFTD is placing on this iconic species. With almost 100% mortality once devils reach breeding age, any advantage an individual devil might have to survive a little longer and reproduce should – over time – spread through the population.

The species has already shown remarkably rapid shifts in their life history and genome, while some are able to mount an immune response and recover from the tumours.

DFTD is spread through biting so we can expect strong evolutionary pressure for devils to become less aggressive towards each other over time.

With these new results, we can now pinpoint for the first time who (healthy, successful males) and when (guarding females after mating) the intense selection pressure on aggressive behaviour in devils will operate.




Read more:
Could Tassie devils help control feral cats on the mainland? Fossils say yes


Ultimately, devils will solve the DFTD problem themselves by evolving resistance, tolerance and changing their behaviour. One of the best things we can do is let evolution take its course, giving a helping hand along the way via well guided management actions.The Conversation

David Hamilton, PhD Candidate in Zoology, University of Tasmania; Elissa Cameron, Professor of Wildlife Ecology, University of Tasmania; Menna Elizabeth Jones, Associate Professor in Zoology, University of Tasmania, and Rodrigo Hamede, Post Doctoral Research Fellow, Conservation Biology and Wildlife Management, University of Tasmania

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Mercury pollution from decades past may have been re-released by Tasmania’s bushfires



File 20190405 114905 1kz1fq7.jpg?ixlib=rb 1.1
Tasmania’s fires may have released mercury previously absorbed by trees.
AAP Image

Larissa Schneider, Australian National University; Kathryn Allen, University of Melbourne, and Simon Haberle, Australian National University

Tasmania’s bushfires may have resulted in the release of significant amounts of mercury from burnt trees into the atmosphere. Our research shows that industrial mercury pollution from decades past has been locked up in west Tasmanian trees.

Mercury occurs naturally in Earth’s crust. Over the past 200 years, industrial activities have mobilised mercury from the crust and released it into the atmosphere. As a consequence, atmospheric mercury concentrations are now three to four times higher than in the pre-industrialisation era.

Mining is the largest source of the global atmospheric mercury, accounting for 37% of mercury emissions. When Europeans first arrived in Australia, there was, of course, no Environmental Protection Act in place to limit emissions from industrial activities. In western Tasmania, where mining has occurred for more than a century, this meant mercury was being released without control into the local atmosphere until changes in technology, market conditions, and later, regulation, conspired to reduce emissions.




Read more:
Australia emits mercury at double the global average


Because mercury is also very persistent in the environment, past mining activity has generated a reservoir of mercury that could be released to the atmosphere under certain conditions. This is a concern because even small amounts of mercury may be toxic and may cause serious health problems. In particular, mercury can threaten the normal development of a child in utero and early in its life.

Tree rings can reveal past mercury contamination

How much mercury has been released into the Australian environment and when has remained largely unknown. However, in a new study we show how mercury levels in Tasmania have dramatically changed over the past 150 years due to mining practices. Long-lived Huon pine, endemic to western Tasmania, is one of the most efficient bioaccumulators of mercury in the world. This makes it a good proxy for tracking mercury emissions in western Tasmania. If concentrations of mercury in the atmosphere are high in a given year, this can be detected in the annual ring of Huon pine for that year.

Mercury pollution from past mining practices in western Tasmania has left a lasting environmental legacy. The sampled trees contained a significant reservoir of mercury that was taken up during the peak mining period in Queenstown. Changes in mercury concentrations in the annual rings of Huon pine are closely aligned with changes in mining practices in the region.

Increased concentrations coincide with the commencement of pyritic copper smelting in Queenstown in 1896. They peak between 1910 and 1920 when smelting was at its height. In 1922, concentrations begin to decline in parallel with the introduction of a new method to separate and concentrate ores. This method required only one small furnace instead of 11 large ones. In 1934, a new dust-collection apparatus was installed in the smelter’s chimney, coinciding with the further decrease in mercury concentrations in nearby Huon pine.

Temporal tree rings of Huon pine, revealing historical mercury pollution.
Author provided

Toxic elements or compounds taken up by vegetation can also be released back into the local environment. Bushfires that burn trees that have accumulated mercury may release this mercury as vapour, dust or fine ash, potentially exposing people and wildlife to the adverse effects of mercury. It is estimated that bushfires release 210,000kg of mercury into the global atmosphere each year. As these fires become more frequent and ferocious in Australia, mercury concentrations in the atmosphere are likely to increase. Mercury released by bushfires can persist in the atmosphere for a year, allowing for long-distance transportation depending on wind strength and direction. This means that mining activity from over a century ago may have regional implications in the near future. The Tasmanian fires in December-February burned almost 200,000 hectares, including areas around Queenstown.

It is not currently possible to know how much mercury has been released by these recent fires. Our results simply highlight the potential risk and the need to better understand the amount of mercury taken up by vegetation that may one day be released back to the atmosphere via bushfires.

Re-release of historical mercury emissions by bushfires.
Author provided



Read more:
Dry lightning has set Tasmania ablaze, and climate change makes it more likely to happen again


Although there is no simple way to remove bio-accumulated mercury from trees, the history of mercury contamination recorded in tree rings provides important lessons. Decreased uptake of mercury after upgrades to the Queenstown copper smelter operations demonstrates the positive impact that good management decisions can have on the amount of mercury released into the environment.

To control mercury emissions globally, the United Nations Environment Programme (UNEP) has developed the Minamata Convention on Mercury. Its primary goal is to protect human health and the environment from the negative effects of mercury. Australia has signed the convention and but has yet to ratify it. Once ratified, Australia would be required to record sources of mercury and quantify emissions, including those from bushfires.

But to do this, the government must first be able to identify environmental reservoirs of mercury. Our study, the first of its kind in the Southern Hemisphere, shows that the long-lived Huon pine can be used to for this purpose. Further work to determine what other tree species record atmospheric emissions of mercury and other toxic elements in other regions of Australia is required.The Conversation

Larissa Schneider, DECRA fellow, Australian National University; Kathryn Allen, Academic, Ecosystem and Forest Sciences, University of Melbourne, and Simon Haberle, Professor, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.