A current affair: the movement of ocean waters around Australia



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Where do the ocean waters that wash the Gold Coast come from?
Flickr/LJ Mears , CC BY-NC-SA

Charitha Pattiaratchi, University of Western Australia; Ems Wijeratne, University of Western Australia, and Roger Proctor, University of Tasmania

Many people in Australia will head to the beach this summer and that’ll most likely include a dip or a plunge into the sea. But have you ever wondered where those ocean waters come from, and what influence they may have?

Australia is surrounded by ocean currents that have a strong controlling influence on things such as climate, ecosystems, fish migrations, the transport of ocean debris and on water quality.

We did a study, published in April 2018, that helps to give us a better understanding of those ocean currents.

Surface currents around the Australian continent.
Ems Wijeratne/Charitha Pattiaratchi/Roger Proctor



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Go with the flow: Indian Ocean

Our 15 year simulation indicates that water from the Pacific Ocean enters the Indonesian Archipelago through the Mindanao current (north) and Halmahera Sea (south).

It then enters the Indian ocean as the Indonesian Throughflow between many Indonesian Islands, with flow through the Timor Passage being the most dominant.

Most of this water flows west as the South Equatorial Current. Re-circulation of the SEC creates the Eastern Gyre that contributes to the Holloway Current. This in turn feeds the Leeuwin Current – the longest boundary current in the world (Ocean currents that flow adjacent to a coastline are called boundary currents)

The Leeuwin Current is the major boundary current along the west coast and as it moves southward. Indian Ocean water is supplied by the South Indian Counter Current increasing the Leeuwin Current transport by 60%.

The Leeuwin Current turns east at Cape Leeuwin, in Western Australia’s south-west, and continues to Tasmania as the South Australian and Zeehan Currents.

The Leeuwin Current passes the lighthouse at the Cape Leeuwin in WA.
Flickr/Cheng, CC BY-NC-ND

There is a strong seasonal variation in the strength of the boundary currents in the Indian Ocean with a progression southwards of the peak transport along the coast.

The Holloway Current peaks in April/May (coinciding with changes in the monsoon winds), the Leeuwin Current reaches a maximum along the west and south coasts in June and August.




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Go with the flow: Pacific Ocean

In the Pacific Ocean, the northern branches of the South Equatorial Current are the main inputs initiating the Hiri Current and East Australian Current.

At around latitude 15 degrees south the currents split in two: southward to form the East Australian Current, and northward to form the Hiri Current which contributes to a clockwise gyre in the Gulf of Papua.

The East Australian Current is the dominant current in the region transporting 33 million cubic metres of water per second southward.

At around 32S, the East Australian Current separates from the coast and 60% of the water flows eastward to New Zealand as the Tasman Front. The remaining 40% flows southward as the East Australian Current extension and contributes to the Tasman Outflow.

The Tasman outflow is the major conduit of water from the Pacific to Indian Ocean and contributes to the Flinders Current, flowing westward from Tasmania and past Cape Leeuwin into the Indian Ocean.

Along the southern continental slope, the Flinders Current appears as an undercurrent beneath the Leeuwin Current and a surface current further offshore. The Flinders Current contributes to the Leeuwin Undercurrent directly as a northward flow, flowing to the north-west of Australia in water depths 300 metres to 800 metres.

Impact of the currents

Understanding ocean circulation is a fundamental tenet of physical oceanography and scientists have been charting the pathways of ocean currents since the American hydrographer Matthew Maury, one of the founders of oceanography, who first charted the Gulf Stream in 1855.

One of the first maps of circulation around Australia was by Halliday (1921) who showed the movement of “warm” and “cold” waters around Australia. Although some of the major features (such as the East Australian Current) were correctly identified, a more fine scale description is now available.

Ocean surface currents around Australia by Halliday 1921.

The unique feature of ocean currents around Australia is that along both east and west coasts they transport warmer water southwards and influence the local climate, particularly air temperature and rainfall, as well as species distribution.




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For example, the south west of Australia is up to 5C warmer in winter and receives more than double the rainfall compared to regions located on similar latitudes along western coastlines of other continents.

Similarly many tropical species of fish are found in the southwest of Australia that hitch a ride on the ocean currents.

The Pacific Ocean is the origin of waters around Australia with a direct link to the east and an indirect link to west.

Ocean water from the Pacific Ocean flows through the Indonesian Archipelago, a region subject to high solar heating and rainfall runoff, creating lower density water. This water, augmented by water from the Indian Ocean, flows around the western and southern coasts, converging along the southern coast of Tasmania.

So next time you head for a dip in the coastal waters around Australian, spare a thought for where that water has come from and where it may be going next.The Conversation

Time for a plunge in the water at Bondi Beach, NSW.
Flickr/Roderick Eime, CC BY-ND

Charitha Pattiaratchi, Professor of Coastal Oceanography, University of Western Australia; Ems Wijeratne, Assistant Professor, UWA Oceans Institute, University of Western Australia, and Roger Proctor, Director, Australian Ocean Data Network, University of Tasmania

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

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Buildings produce 25% of Australia’s emissions. What will it take to make them ‘green’ – and who’ll pay?


Igor Martek, Deakin University and M. Reza Hosseini, Deakin University

In signing the Paris Climate Agreement, the Australian government committed to a global goal of zero net emissions by 2050. Australia’s promised reductions to 2030, on a per person and emissions intensity basis, exceed even the targets set by the United States, Japan, Canada, South Korea and the European Union.

But are we on the right track to achieve our 2030 target of 26-28% below 2005 levels? With one of the highest population growth rates in the developed world, this represents at least a 50% reduction in emissions per person over the next dozen years.




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Consider the impact of one sector, the built environment. The construction, operation and maintenance of buildings accounts for almost a quarter of greenhouse gas emissions in Australia. As Australia’s population grows, to an estimated 31 million in 2030, even more buildings will be needed.

In 2017, around 18,000 dwelling units were approved for construction every month. Melbourne is predicted to need another 720,000 homes by 2031; Sydney, 664,000 new homes within 20 years. Australia will have 10 million residential units by 2020, compared to 6 million in 1990. Ordinary citizens might be too preoccupied with home ownership at any cost to worry about the level of emissions from the built environment and urban development.

What’s being done to reduce these emissions?

The National Construction Code of Australia sets minimal obligatory requirements for energy efficiency. Software developed by the National Housing Rating Scheme (NatHERS) assesses compliance.

Beyond mandatory minimum requirements in Australia are more aspirational voluntary measures. Two major measures are the National Australian Built Environment Rating System (NABERS) and Green Star.

This combination of obligatory and voluntary performance rating measures makes up the practical totality of our strategy for reducing built environment emissions. Still in its experimentation stage, it is far from adequate.

An effective strategy to cut emissions must encompass the whole lifecycle of planning, designing, constructing, operating and even decommissioning and disposal of buildings. A holistic vision of sustainable building calls for building strategies that are less resource-intensive and pollution-producing. The sustainability of the urban landscape is more than the sum of the sustainability of its component buildings; transport, amenities, social fabric and culture, among other factors, have to be taken into account.

Australia’s emission reduction strategy fails to incorporate the whole range of sustainability factors that impact emissions from the built environment.

There are also much-reported criticisms of existing mandatory and voluntary measures. A large volume of research details the failure of voluntary measures to accurately evaluate energy performance and the granting of misleading ratings based on tokenistic gestures.




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On top of that, the strategy of using front runners to push boundaries and win over the majority has been proven ineffective, at best. We see compelling evidence in the low level of voluntary measures permeating the Australian building industry. Some major voluntary rating tools have penetration rates of less than 0.5% across the Australian building industry.

As for obligatory tools, NatHERS-endorsed buildings have been shown to underperform against traditional “non-green” houses.

That said, voluntary and obligatory tools are not so much a weak link in our emission reduction strategy as the only link. And therein lies the fundamental problem.

So what do the experts suggest?

We conducted a study involving a cohort of 26 experts drawn from the sustainability profession. We posed the question of what must be done to generate a working strategy to improve Australia’s chances of keeping the carbon-neutral promise by 2050 was posed. Here is what the experts said:

Sustainability transition in Australia is failing because:

  • government lacks commitment to develop effective regulations, audit performance, resolve vested interests (developers), clarify its own vision and, above all, sell that sustainability vision to the community

  • sustainability advocates are stuck in isolated silos of fragmented markets (commercial and residential) and hampered by multiple jurisdictions with varied sustainability regimes

  • most importantly, end users just do not care – nobody has bothered to communicate the Paris Accord promise to Joe and Mary Citizen, let alone explain why it matters to them.

Tweaking the rating tools further would be a good thing. Getting more than a token few buildings rated would be better. But the show-and-tell display of a pageant of beautiful, green-rated headquarters buildings from our socially responsible corporations is not going to save us. Beyond the CBD islands of our major cities lies a sea of suburban sprawl that continues to chew up ever more energy and resources.




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It costs between 8% and 30% more than the usual costs of a building to reduce emissions. Someone needs to explain to the struggling home owner why the Paris climate promise is worth it. Given the next election won’t be for a few months, our political parties still have time to formulate their pitch on who exactly is expected to pay.The Conversation

Igor Martek, Lecturer In Construction, Deakin University and M. Reza Hosseini, Lecturer in Construction, Deakin University

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

It’s time to restore public trust in the governing of the Murray Darling Basin



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Going all the way back: rules for the Murray Darling Basin are in Australia’s constitution.
KnitSpirit/Flickr, CC BY-NC-SA

Jason Alexandra, RMIT University

Fish deaths in the Darling River have once more raised the public profile of incessant political controversies about the Murray Darling Basin. These divisive debates reveal the deeply contested nature of reforms to water policy in the Basin.

It feels like Australia has been here before – algae blooms are not uncommon in these rivers. In 1992, the Darling suffered the world’s largest toxic algal bloom, over 1,000 kilometres long. This crisis became an iconic catalyst, and helped prompt the state and federal governments agreeing to water reforms in 1994.

Hopefully, our current crisis may be an opportunity to shine a strong light on the complexities of governing the Basin, and initiate the meaningful reforms needed to restore public trust.




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Forewarned is forearmed

The rivers of the basin are unique and precious. Australia needs high quality and independent science to understand them and guide their management. Unfortunately in 2012 state and federal governments cut three important programs that provided vital research on the Basin’s rivers:

So while yesterday’s announcement of A$5 million funding to a new native fish recovery program is welcome, good science alone is not enough. Good policy processes and robust institutions are needed to apply this information. We cannot continue to ignore expert warnings.

A crisis of trust

Since a 2017 Four Corners program exposed disturbing allegations of water theft and corruption, the media has revealed a host of further probity issues.

These and a plethora of formal inquiries into MDB governance indicates a crisis of trust, legitimacy and public confidence – in short, a loss of authority.

The 2018 federal Senate inquiry documents a litany of concerns, while disturbing evidence given at a South Australian Royal Commission raised substantive doubts about failures to heed the best scientific advice in the development of the Basin Plan.




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More Commonwealth oversight is not enough

Without doubt pressure is mounting for more reforms. The Senate’s Rural and Regional Affairs Committee and the Productivity Commission have recommended splitting the Murray Darling Basin Authority into two entities – the MDB Corporation and a MDB Regulator – in order to clearly separate the Commonwealth’s regulatory oversight from other roles.

These proposals deserve critical scrutiny. Structural reorganisation can provide an illusion of government action, but can have long-term effects on the efficacy and justice of water governance.

The Murray Darling has a unique place in Australia’s history, environment, economy and culture. Agreements about its governance have their origins in debates leading up to Federation in 1901. Any renegotiation needs to respect the Constitution and the different legal powers of the states and the Commonwealth.

So reform to institutional arrangements need bespoke design. These are the legitimate remit of our discursive democracy. Nonetheless, the OECD’s 12 water governance principles usefully provide guidance about the need for clarity of roles, transparency, effectiveness, efficiency and broad stakeholder engagement.

Current calls for reorganisation focus on clarifying the Commonwealth’s regulatory role, but this is fairly narrow. Reforms are needed at all scales.

The governance challenges in the MDB require modernisation and redesign of arrangements across regional, state and Commonwealth agencies. This includes structuring “constructive tensions” that ensure transparency and accountability. Just like the police don’t control the courts, we need to more clearly define and separate roles in the water sector.

Embracing radical transparency

We need all water agencies to adopt a formal charter of transparency and openness. All state and Commonwealth agencies should open their books to scrutiny, rather than hiding information behind claims of “commercial in confidence” or opaque “freedom of information” processes.

Greater transparency measures should also be a condition of all water licences. It’s entirely feasible to create modern monitoring regimes, using state-of-the art digital metering coupled with annual water-use declarations. These would be similar to tax returns enforced with random audits and satellite verification of areas irrigated. If made publicly available, all interested parties could audit water extractions.

But doubts don’t exclusively focus on irrigators’ compliance. We also need to address the states and their willingness and capability to enforce regulations. Policies of radical transparency could be supported with openly available water data. With digital meters and automated gauging of river flows, we could create a computer platform where anybody could develop river models using real data, in near real-time.

Harnessing the power of citizen involvement, trust and openly sharing information has been a hallmark of Australia’s landcare and natural resource management. This is where we should look for the next generation of governance in the Basin.

Open books means communities, industries, research and educational institutions can all help monitor our institutions and ensure rivers are managed in the public’s interest.




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Finally, droughts should not come as surprise. They are a recurrent feature of the Basin. With climate change, more frequent and intense droughts are predicted. As a nation we can do better than lurching from crisis to crisis each time drought returns.

We need careful deliberation about the institutions that will rebuild public confidence and restore trust in the governing of the Murray Darling. It’s time to develop a 21st century system that is cooperative, transparent and just.The Conversation

Jason Alexandra, PhD candidate, RMIT University

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

How Australian wildlife spread and suppress Ross River virus



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Mozzies feed on many native species, including the Nankeen Night Heron.
Janis Otto/flikr

Eloise Stephenson, Griffith University; Cameron Webb, University of Sydney, and Emily Johnston Flies, University of Tasmania

Ross River virus is Australia’s most common mosquito-borne disease. It infects around 4,000 people a year and, despite being named after a river in North Queensland, is found in all states and territories, including Tasmania.

While the disease isn’t fatal, it can cause debilitating joint pain, swelling and fatigue lasting weeks or even months. It can leave sufferers unable to work or look after children, and is estimated to cost the economy A$2.7 to A$5.6 million each year.

There is no treatment or vaccine for Ross River virus; the only way to prevent is to avoid mosquito bites.




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Explainer: what is Ross River virus?


Mosquitoes pick up the disease-causing pathogen by feeding on an infected animal. The typical transmission cycle involves mosquitoes moving the virus between native animals but occasionally, an infected mosquito will bite a person. If this occurs, the mosquito can spread Ross River virus to the person.

Animal hosts

Ross River virus has been found in a range of animals, including rats, dogs, horses, possums, flying foxes, bats and birds. But marsupials – kangaroos and wallabies in particular – are generally better than other animals at amplifying the virus under experimental infection and are therefore thought to be “reservoir hosts”.

The virus circulates in the blood of kangaroos and wallabies for longer than other animals, and at higher concentrations. It’s then much more likely to be picked up by a blood-feeding mosquito.

Kangaroos are a common sight around Australia’s coastal wetlands.
Dr Cameron Webb (NSW Health Pathology), Author provided

Dead-end hosts

When we think of animals and disease we often try to identify which species are good at transmitting the virus to mosquitoes (the reservoir hosts). But more recently, researchers have started to focus on species that get bitten by mosquitoes but don’t transmit the virus.

These species, known as dead-end hosts, may be important for reducing transmission of the virus.

With Ross River virus, research suggests birds that get Ross River virus from a mosquito cannot transmit the virus to another mosquito. If this is true, having an abundance of birds in and around our urban environments may reduce the transmission of Ross River virus to animals, mosquitoes and humans in cities.

Other reservoir hosts?

Even in areas with a high rates of Ross River virus in humans, we don’t always find an abundance of kangaroos and wallabies. So there must be other factors – or animals yet to be identified as reservoirs or dead-end hosts – playing an important role in transmission.

Ross River virus is prevalent in the Pacific Islands, for instance, where there aren’t any kangaroos and wallabies. One study of blood donors in French Polynesia found that 42.4% of people tested had previously been exposed to the virus. The rates are even higher in American Samoa, where 63% of people had been exposed.




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It’s unclear if the virus has recently started circulating in these islands, or if it’s been circulating there longer, and what animals have been acting as hosts.

What about people?

Mosquitoes can transmit some viruses, such as dengue and Zika between people quite easily.

But the chances of a mosquito picking up Ross River virus when biting an infected human is low, though not impossible. The virus circulates in our blood at lower concentrations and for shorter periods of time compared with marsupials.

Stop mozzies biting with insect repellents.
Elizaveta Galitckaia/Shutterstock

If humans are infected with Ross River virus, around 30% will develop symptoms of joint pain and fatigue (and sometimes a rash) three to 11 days after exposure, while some may not experience any symptoms until three weeks after exposure.

To reduce your risk of contracting Ross River virus, take care to cover up when you’re outdoors at sunset and wear repellent when you’re in outdoor environments where mosquitoes and wildlife may be frequently mixing.




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The Conversation


Eloise Stephenson, PhD Candidate, Griffith University; Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of Sydney, and Emily Johnston Flies, Postdoctoral Research Fellow (U.Tasmania), University of Tasmania

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

What happens after you take injured wildlife to the vet?



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Many Australians bring injured wild animals to vets, but not many people know what happens next.
RSPCA ACT

Bronwyn Orr, University of Sydney

Australia’s wildlife is unique and endearing, with many species found nowhere else in the world. Unfortunately, it isn’t rare to encounter sick or injured wildlife around your home or by the side of the road. My research, recently published in the Australian Veterinary Journal, estimates between 177,580 and 355,160 injured wild animals are brought into NSW veterinary clinics alone every year.

But until now, very little was known about what happens to wildlife after they’re brought to a vet. My colleagues and I surveyed 132 veterinary clinics around Australia, examining the demands and expectations of treating wildlife. We also looked for risks to animal welfare as a result of these findings.

Most clinics only saw a handful of wildlife patients every week, with birds and marsupials such as possums the most common. Sadly, the majority (82%) of wildlife arrived in veterinary care due to trauma of some kind. The most common cause was animals being hit by cars, followed by undefined trauma and predation by another animal.




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Most clinics examined and treated wildlife for free, with less than 10% receiving some kind of payment. These were usually made by wildlife rehabilitation groups or members of the public.

Due to the painful and serious nature of trauma, around a third of clinics reported euthanasia was the most common outcome for wildlife at their clinic. More positively, more than half indicated that wildlife were usually passed onto wildlife rehabilitators, suggesting this is the most common outcome.

Kangaroo with burns to all four limbs after a fire.
Author Provided

Almost three quarters of veterinary clinics said they only saw wildlife when they had spare time. This is concerning, as delays to treatment raises serious animal welfare concerns.

Additionally, many veterinary clinics indicated they felt a lack of time, knowledge and skills interfered with their ability to treat wildlife.

As veterinary clinics are small businesses, wildlife present a conundrum. They are not owned (although technically they are owned by the Crown), expect treatment with no payment and don’t look like the usual pets seen by most vets. With clinics full of paying clients expecting prompt treatment, it can be hard to prioritise wildlife.

So what is the solution?

Ideally, either the state or federal government would take financial responsibility for wildlife. The federal government does pay for some wildlife treatment at private veterinary clinics, but this is part of a biosecurity monitoring scheme and isn’t open to most clinics.




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Donations from the public to treat wildlife would also likely be welcomed. However, help can come in other ways. One large clinic in Sydney is trialling an in-house wildlife carer, who would triage wildlife and take responsibility for ensuring wildlife are prioritised. Appointing a “wildlife champion” in a clinic is another option, where an interested vet or nurse is designated the “go to” person for wildlife cases.

Wombat in the wild.
From Shutterstock

What should you do if you find injured wildlife?

1. Call your local wildlife care group for advice

Some animals aren’t actually injured, such as fledgling birds which are learning to fly, and others (such as goannas) can be dangerous, so be sure to seek advice before approaching wildlife. If you don’t know who your local wildlife care group is, type into a search engine “wildlife carer” to locate one near you.

2. Keep yourself safe

Armed with advice from a wildlife carer, ensure you don’t put yourself in a risky situation to rescue wildlife. Take care around busy roads, use a barrier between yourself and the injured animal (such as a towel or welding gloves) and avoid the bitey end! Wildlife are inherently fearful of people, which means they might attack if scared.




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3. Secure the injured animal before transport

You don’t want an injured animal to escape in your car on the way to the vet. If the injured animal is a bird, small reptile or baby marsupial, a cardboard box with air holes and lined with a towel makes a good transport container. Don’t offer wildlife food, as they have very special diets and digestive systems.

4. Give as much information as possible

When you get to the vet, ensure you provide detailed information on where you found the animal. If the animal is healthy enough to enter wildlife rehabilitation, the wildlife carers will need to release the animal as close as possible to the location where it was found. This is because many animals, such as possums, are fiercely territorial and often die if relocated outside their territory.


Ultimately, many injured wild animals cannot be saved and will be euthanased after being dropped off at a veterinary clinic. This is not a bad outcome. Wildlife aren’t pets – they need to be fit to survive if they are ever going to have a chance in the wild. Injuries such as a badly broken wing or losing an eye would condemn wildlife upon release to starvation or predation.

It is much kinder to humanely euthanase injured wildlife which have no chance of survival rather than let them suffer a prolonged death in the wild. Even if the animal you drop off at the vet is ultimately euthansed, you have still saved it from prolonged suffering.The Conversation

Bronwyn Orr, Veterinarian and PhD candidate, University of Sydney

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

The economics of ‘cash for cane toads’ – a textbook example of perverse incentives



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It is estimated there are now more than 200 million cane toads across Queensland and northern New South Wales.
Shutterstock

David Smerdon, The University of Queensland

Economics teachers can all thank Pauline Hanson for providing an excellent example to add to their classes.

Indeed, it’s rare that Economics 101 lessons are as readily on display as in the Queensland senator’s “cash for cane toads” proposal.

Both textbook wisdom and historical failures tell us the plan won’t work.

Hanson’s proposal involves paying welfare recipients 10 cents for each toad they collect (alive) and hand over to their local council. The council would then kill the toads humanely in large freezers.

The senator is right to be concerned about the cane toad problem. Introduced in the 1930s as a biological fix to control native beetles eating sugar cane crops, the animals have prospered with devastating impact on native flora and fauna. It’s estimated there are now more than 200 million across Queensland and northern New South Wales.




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They carry toxins at all stages of their life cycle, including as eggs. Ingesting the toxin is fatal to many Australian species. Their voracious appetites both deplete insect populations such as honey bees and threaten the food sources of other native animals.

The reason Hanson’s idea is fundamentally flawed, both in theory and in practice, has to do with incentives.

A native of Latin America, the cane toad has adapted well to Australia due to the lack of natural predators. Toads have spread from Queensland as far west as Broome, Western Australia.
http://www.shutterstock.com

History repeating

Incentives are central to economics. They are ingrained in the laws of demand and supply, and the setting of interest rates and taxes.

Humans react to incentives. The key is setting them just right by accounting for all of the costs involved.

This is the most obvious and least interesting problem with the scheme. In NSW and Queensland, you can earn 10 cents by returning an empty drink container to your local supermarket. That’s a task exponentially easier than catching a cane toad and delivering it alive to your local council chambers.

If it were just a case of the incentives being too low, the solution would be simple: raise the price.

However, this would run into a surprising phenomenon called the Cobra effect. Also known as “perverse incentives”, it describes a situation in which a seemingly well-intentioned proposal actually makes things much worse.

The Cobra effect is named after a curious incident from British Colonial India. Faced with a cobra outbreak, the local government of Delhi enacted a cash-for-cobras scheme, with initial success. But as cobras became harder to find, the locals responded to the incentives in a completely logical way: they started breeding the snakes to claim their bounties. When the scheme was scrapped, breeders released their now-worthless snakes, resulting in the city having more cobras than before the scheme.

A similar case comes from French-run Vietnam.

When the colonial government built a sewerage system under Hanoi early in the 20th century, it inadvertently helped create a rat plague. Its solution was a cash-for-rats scheme – though to save the government having to dispose of hundreds of thousands of rat carcasses, it only required collectors turning in a rat’s tail to claim their bounty.

Crowd displeasers

The consequences this time were not only the creation of pop-up rat-breeding farms, but also hordes of tail-less rats roaming the city streets.

Of course, at its current pittance of 10 cents a toad, Hanson’s proposal is unlikely to lead to lucrative cane-toad farming.

It’s a reasonable claim that the incentives would simply be too low to be effective, leading to no change in the status quo (besides large freezers sitting empty at local council buildings).

Yet even as a toothless policy, a cash-for-cane-toads scheme could produce other unintended consequences.

When people already do something out of their own goodness, like volunteering, putting a price on the activity by offering chump change can actually put them off. Behavioural economists call this “crowding out of intrinsic motivation”. It explains why blood donation rates are no different between countries that pay donors (such as the United States) and those that rely on volunteers (such as Australia).




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One of the best-known examples in economics involved a day-care in Israel that introduced small fines for parents who were late picking up their children. The result was a doubling of lateness. Before the fine, parents would try to come on time because it was the right thing to do. After the fine, however, that moral value had a price: about three dollars.

Notably, parents continued to come late after the fines were removed. Parents who pay pocket money for chores need only imagine how their own kids would respond if they moved to a “volunteer system”.

Thus economics gives us a third reason to doubt Senator Hanson’s proposal will work: the risk that altruistic citizens who have culled cane toads for free will be discouraged by a price being put on the activity.

Instead of considering the “priceless” value of native ecosystems when spotting an offending creature, people may start weighing up their efforts against 10 cents. This cost-benefit thinking could continue even after the compensation scheme ends.

The cane toad is the world’s largest toad. An adult’s body is typically 10-15 cm in length, but some grow at large as 24 cm.
http://www.shutterstock.com

That’s the crux of why this payment scheme wouldn’t work. Setting a high price perverts the incentives, while setting a low price crowds out intrinsic motivations. In either case, taxpayer money is wasted and the toad problem is potentially made worse.

The best approach is to leave prices out of it and trust our experts, who are continuing to come up with remarkably innovative ideas to solve the cane toad problem.

Senator Hanson’s proposal was no doubt made with the best of intentions. Unfortunately, in reality the only real beneficiaries would be economics teachers.The Conversation

David Smerdon, Assistant Professor, School of Economics, The University of Queensland

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

How is oxygen ‘sucked out’ of our waterways?



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Dead fish are a source of food for bacteria, which then extract oxygen from the river.
AAP

Stuart Khan, UNSW

A million fish have died in the Murray Darling basin, as oxygen levels plummet due to major algal blooms. Experts have warned we could see more mass deaths this week.




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Explainer: what causes algal blooms, and how we can stop them


Fingers have been pointed at poor water management after a long period of drought. However, mass fish deaths can also be caused by floods, and even raw sewage.

So what’s going on when oxygen gets “sucked out of the water”?

The phenomenon is very well known to water quality engineers; we call it “biochemical oxygen demand”. To understand it, we need to talk about a little bit of biology and a little bit of chemistry.

When oxygen meets water

Oxygen molecules are soluble in water in the same way that sugar is soluble in water. Once its dissolved, you can’t see it (and, unlike sugar, oxygen is tasteless).

The maximum amount of oxygen that you can dissolve in water depends on a number of factors, including the water temperature, ambient air pressure, and salinity. But roughly speaking, the maximum amount of dissolvable oxygen, known as the “saturation concentration” is typically around 7-10 milligrams of oxygen per litre of water (7-10 mg/L).

This dissolved oxygen is what fish use to breathe. Fish take water in through their mouths and force it through their gill passages. Gills, like our lungs, are full of blood vessels. As water passes over the thin walls of the gills, dissolved oxygen is transferred into the blood and then transported to the fish’s cells. The higher the oxygen concentration in the water, the easier it is for this transfer to occur.

Once in the cells, the oxygen molecules play a key role in the process of “aerobic respiration”. The oxygen reacts with energy-rich organic substances, such as sugars, carbohydrates and fats to break them down and release energy for the cells. The main waste product from this process is carbon dioxide (CO₂). This is why we all need to breathe in oxygen and we breathe out carbon dioxide. Fish do that too. A simple way to express this is:

Organic substances + Oxygen Carbon dioxide + Water + Energy

The Hunter River in NSW suffered a ‘blackwater’ event in 2016 when floodwaters washed organic matter into the river.
Andrew S/Flickr, CC BY-SA

What is the biochemical oxygen demand?

Just like fish and people, many bacteria gain energy from processes of aerobic respiration, according to the simplified chemical reaction shown above. Therefore, if there are organic substances in a waterway, the bacteria that live in that waterway can consume them. This is an important process of “biodegradation” and is the reason our planet is not littered by the carcasses of animals that have died over many thousands of years. But this form of biodegradation also consumes oxygen, which comes from dissolved oxygen in the waterway.

Rivers can replenish their oxygen from contact with the air. However this is a relatively slow process, especially if the water is stagnant (flowing creates turbulence and mixes in more oxygen). So if there is a lot of organic matter present and bacteria are feasting on it, oxygen concentrations in the river can suddenly drop.

Obviously, “organic substances” can include many different things, such as sugars, fats and proteins. Some molecules contain more energy than others, and some are easier for the bacteria to biodegrade. So the amount of aerobic respiration that will occur depends on the exact chemical nature of the organic substances, as well as their concentration.

Therefore, instead of referring to the concentration of “organic substances”, we more commonly refer to the thing that really matters: how much aerobic respiration the organic substances can trigger and how much oxygen this will cause to be consumed. This is what we call the biochemical oxygen demand (BOD) and we usually express it as a concentration in terms of milligrams of oxygen per litre of water (mg/L).

Like us, bacteria don’t consume all of the food which is available to them instantly – they graze on it over time. Biodegradation therefore can take days, or longer. So when we measure the BOD of a contaminated water sample, we need to assess how much oxygen is consumed (per litre of water) over a specified period of time. The standard period of time is usually five days and we refer to this value as the BOD5 (mg/L).

Murray cod pull oxygenated water through their gills, transferring it to their bloodstream. Without oxygen in the water, they die.
Guo Chai Lim/Flickr, CC BY-NC-SA

As I mentioned earlier, clean water might only have a concentration of dissolved oxygen of up to around 7-10 mg/L. So if we add organic material in a concentration which has a higher BOD5 than this, we can expect it to deplete the ambient dissolved oxygen concentration during the next five days.




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This phenomena is the main reason for which biological sewage treatment was invented. Raw (untreated) municipal sewage can have a BOD5 of 300-500 mg/L. If this were discharged to a clean waterway, the typical base-level of 7-10 mg/L of oxygen would be consumed, leaving none available for fish or other aquatic organisms.

So the purpose of biological sewage treatment is to grow lots of bacteria in large tanks of sewage and provide them with plentiful oxygen for aerobic respiration. To do this, air can be bubbled through the sewage, or sometimes surface aerators are used to churn up the sewage.

By supplying lots of oxygen, we ensure the BOD5 is effectively consumed while the sewage is still in the tanks, before it’s released to the environment. Well treated sewage can have a BOD5 as low as 5 mg/L, which can then be further diluted as it’s discharged to the environment.

In the case of the Darling river, the high BOD load was created by algae, which died when temperatures dropped. This provided a feast for bacteria, lowering oxygen, which in turn killed hundreds of thousands of fish. Now, unless we clean the river, those rotting fish could become fodder for another round of bacteria, triggering a second de-oxygenation event.The Conversation

Stuart Khan, Professor of Civil & Environmental Engineering, UNSW

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