What Would Happen if Honeybees Went Extinct?
Monthly Archives for April 2019
Dingoes and humans were once friends. Separating them could be why they attack
Katie Woolaston, Queensland University of Technology
Two small children were hospitalised in recent weeks after being attacked by dingoes on K’gari (Fraser Island).
The latest attack involved a 14-month-old boy who was dragged from his family campervan by dingoes, an incident that could have ended with much more serious consequences than the injuries he sustained.
Fraser Island, famous for its wild dingo population, was renamed K’Gari in 2017. And the number of tourists involved in negative interactions with dingoes appears to be increasing.
Read more:
Why do dingoes attack people, and how can we prevent it?
The dingo, a wild dog of the Canis genus, were likely brought to Australia by Asian seafarers around 4,000 years ago.
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While dingoes exist in many parts of Australia today, those on K’gari are thought to be “special” because of their genetic purity. This means they have not interbred with wild and domestic dogs to the same extent mainland dingoes have, and so are considered the purest bred dingoes in Australia.
They are legally protected because of this special status, and because they live in a national park and World Heritage Area. Unfortunately, it is precisely this protection and separation from humans that has driven much of the increase in interaction and aggression towards people.
Read more:
Like cats and dogs: dingoes can keep feral cats in check
This ongoing human-dingo conflict on K’Gari shows how our laws and management practices can actually increase negative encounters with wildlife when they don’t consider the history, ecology and social circumstances of the conflict area.
Law and policy ‘naturalised’ dingoes
The island’s laws and policies, such as the international World Heritage Convention and the more local Fraser Island Dingo Conservation and Risk Management Strategy, are focused on conserving a particular human idea of “natural wilderness”.
In practice, this means the management policy focuses on “naturalising” the dingo by effectively separating them from people and the sources of food they bring.
But dingoes, although wild animals, have never effectively been naturalised on K’Gari, so our attempts to maintain their “natural” and “wild” status is not entirely accurate.
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Dingoes have a long history of being close with Aboriginal people. This human-dingo relationship continued as the island was used for mining and logging, as employees also lived with dingoes. They were fed by people, scavenged scraps from rubbish tips, and fed on leftover fish offal.
It is only in the last few decades we have sought to rewild dingoes by removing all forms of human-sourced food, separating them from human settlement.
Read more:
Living blanket, water diviner, wild pet: a cultural history of the dingo
Separating the animals from humans won’t work, however, when more than 400,000 tourists visit K’Gari every year, expecting to see a dingo.
International law and local management prioritise tourism, and a tourism-based economy is certainly preferable to the logging and sand-mining economies that existed before the national park was given World Heritage status in 1992.
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But are such large visitor numbers in a relatively small space sustainable?
This question has been asked often, including by the Queensland government in their Great Sandy Region Management Plan.
Yet, there has been no serious consideration given to reducing tourist numbers or increasing fees, despite research suggesting visitors are willing to sacrifice some access for improved environmental outcomes and less crowding.
Such proposals have been specifically rejected by decision-makers within the Dingo Management Plan.
Read more:
Dingoes do bark: why most dingo facts you think you know are wrong
So where does that leave us?
We essentially have three options:
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if we wish to stick with the policy of dingo naturalisation and human separation, we must change our attitudes and values towards dingoes so people maintain an appropriate distance and do not inadvertently feed them. This can happen with education, fines and collaboration. While this is essentially what policies have attempted so far, there has been little effect on overall incident numbers
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we can take the naturalisation policy to its expected endpoint and completely separate tourists and dingoes. This may mean more fencing, greater fines and fewer annual visitors so rangers can educate and manage all visitors effectively
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we can drastically reevaluate how we value wildlife and how we place ourselves within the natural world. This would see an enormous overhaul of the regulatory framework, and would also require a deeper understanding of all the causes of conflict, other than just the immediate issue of tourism, habituation and feeding.
In practice, an effective dingo management policy would probably require a combination of all three options to maintain the pristine state of K’Gari, conserve the dingo population and improve human safety.
Katie Woolaston, Lawyer, Queensland University of Technology
This article is republished from The Conversation under a Creative Commons license. Read the original article.
How many species on Earth? Why that’s a simple question but hard to answer
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Tanya Latty, University of Sydney and Timothy Lee, University of Sydney
You’d think it would be a simple piece of biological accounting – how many distinct species make up life on Earth?
But the answer may come as a bit of a shock.
We simply don’t know.
We know more accurately the number of books in the US Library of Congress than we know even the order or magnitude – millions and billions and so on – of species living on our planet, wrote the Australian-born ecologist Robert May.
Read more:
Trapdoor spider species that stay local put themselves at risk
Current estimates for the number of species on Earth range between 5.3 million and 1 trillion.
That’s a massive degree of uncertainty. It’s like getting a bank statement that says you have between $5.30 and $1 million in your account.
So why don’t we know the answer to this fundamental question?
It’s hard to count life
Part of the problem is that we cannot simply count the number of life forms. Many live in inaccessible habitats (such as the deep sea), are too small to see, are hard to find, or live inside other living things.
So, instead of counting, scientists try to estimate the total number of species by looking for patterns in biodiversity.
In the early 1980s, the American entomologist Terry Erwin famously estimated the number of species on Earth by spraying pesticides into the canopy of tropical rainforest trees in Panama. At least 1,200 species of beetle fell to the ground, of which 163 lived only on a single tree species.
Assuming that each tree species had a similar number of beetles, and given that beetles make up about 40% of insects (the largest animal group), Erwin arrived at a controversial estimate of 30 million species on Earth.
Many scientists believe the 30 million number is far too high. Later estimates arrived at figures under 10 million.
In 2011, scientists used a technique based on patterns in the number of species at each level of biological classification to arrive at a much lower prediction of about 8.7 million species.
Shutterstock/Suttipon Thanarakpong
All creatures great and very, very small
But most estimates of global biodiversity overlook microorganisms such as bacteria because many of these organisms can only be identified to species level by sequencing their DNA.
As a result the true diversity of microorganisms may have been underestimated.
After compiling and analysing a database of DNA sequences from 5 million microbe species from 35,000 sites around the world, researchers concluded that there are a staggering 1 trillion species on Earth. That’s more species than the estimated number of stars in the Milky Way galaxy.
But, like previous estimates, this one relies on patterns in biodiversity, and not everyone agrees these should be applied to microorganisms.
It’s not just the microorganisms that have been overlooked in estimates of global biodiversity. We’ve also ignored the many life forms that live inside other life forms.
Most – and possibly all – insect species are the victim of at least one or more species of parasitic wasp. These lay their eggs in or on a host species (think of the movie Aliens, if the aliens had wings). Researchers suggest that the insect group containing wasps may be the largest group of animals on the planet.
What do we mean by species?
A more fundamental problem with counting species comes down to a somewhat philosophical issue: biologists do not agree on what the term “species” actually means.
The well-known biological species concept states that two organisms belong to the same species if they can interbreed and produce fertile offspring. But since this concept relies on mating, it cannot be used to define species of asexual organisms such as many microorganisms as well as some reptiles, birds and fish.
It also ignores the fact that many living things we consider separate species can and do interbreed. For example, dogs, coyotes and wolves readily interbreed, yet are usually considered to be separate species.
PLOS One (L. David Mech et al), CC BY
Other popular species definitions rely on how similar individuals are to one another (if it looks like a duck, it is a duck), their shared evolutionary history, or their shared ecological requirements.
Yet none of these definitions are entirely satisfactory, and none work for all life forms.
There are at least 50 different definitions of a species to choose from. Whether or not a scientist chooses to designate a newly found life form as a new species or not can come down to their philosophical stance about the nature of a species.
The cost of species loss
Our ignorance about the true biodiversity on our planet has real consequence. Each species is a potential treasure trove of solutions to problems including cures for disease, inspirations for new technologies, sources of new materials and providers of key ecosystem services.
Yet we are living in an age of mass extinction with reports of catastrophic insect declines, wide-scale depopulation of our oceans and the loss of more than 50% of wildlife within the span of a single human life.
Our current rate of biodiversity loss means we are almost certainly losing species faster than we are naming them. We are effectively burning a library without knowing the names or the contents of the books we are losing.
So while our estimate of the number of species on the planet remains frustratingly imprecise, the one thing we do know is that we have probably named and described only a tiny percentage of living things.
New species are turning up all the time, at a rate of roughly 18,000 species each year. For example, researchers in Los Angeles found 30 new species of scuttle fly living in urban parks, while researchers also in the US discovered more than 1,400 new species of bacteria living in the belly buttons of university students.
Even if we take the more conservative estimate of 8.7 million species of life on Earth, then we have only described and named about 25% of life forms on the planet. If the 1 trillion figure is correct, then we have done an abysmally poor job, with 99.99% of species still awaiting description.
It’s clear our planet is absolutely teeming with life, even if we cannot yet put a number to the multitudes. The question now is how much of that awe-inspiring diversity we choose to save.
Tanya Latty, Senior Lecturer, School of Life and Environmental Sciences, University of Sydney and Timothy Lee, Associate Lecturer in Life and Environmental Sciences, University of Sydney
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Germany’s Bird Diversity
It’s not worth wiping out a species for the Yeelirrie uranium mine
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One day before calling the election, the government approved the controversial Yeelirrie uranium mine in the remote wilderness of Western Australia, about 500km north of Kalgoorlie.
The Tjiwarl Traditional Owners have fought any uranium mining on their land for the last 40 years, and the decision by the government wasn’t made public until the day before Anzac Day.
This region is home to several of Australia’s deposits of uranium and not only holds cultural significance as part of the Seven Sisters Dreaming Songline, but also environmental significance.
Read more:
An end to endings: how to stop more Australian species going extinct
If the mine goes ahead, groundwater levels would drop by 50cm and wouldn’t fully recover for 200 years. And 2,422 hectares of native vegetation would be cleared.
I visited the site 16 years ago and, like the rest of the Western Australian outback, there’s a wonderful paradox where the land appears barren, but is, in fact, rich with biodiversity.
Photo G M Mudd
Native animals living in underground water, called stygofauna, are one such example of remarkable Australian fauna that aren’t obvious at first glance. These animals are under threat of extinction if the Yeelirrie uranium mine goes ahead.
Stygofauna are ecologically fragile
Most stygofauna are very tiny invertebrates, making up species of crustaceans, worms, snails and diving beetles. Some species are well adapted to underground life – they are typically blind, pale white and with long appendages to help them find their way in total darkness.
Photograph by Giulia Perina, Subterranean Ecology Pty Ltd
In 2016, the Western Australian Environmental Protection Agency (EPA) advised against building the Yeelirrie uranium mine because it would threaten the stygofauna species there, despite the proposed management strategies of Cameco Australia, the mine owner.
Stygofauna are extremely local, having evolved in the site they’re found in. This means individual species aren’t found anywhere else in the world.
EPA chairman Tom Hatton said:
Despite the proponent’s well-considered management strategies, based on current scientific understanding, the EPA concluded that there was too great a chance of a loss of species that are restricted to the impact area.
Yeelirrie has a rich stygofauna habitat, with 73 difference species recorded.
Photograph by Giulia Perina, Subterranean Ecology Pty Ltd
And to get to the uranium deposit, the miners need to dig through the groundwater, a little like pulling the plug in the middle of the bathtub. Stygofauna have adapted to living at different levels of the water, so pulling out the plug could dry out important parts of their habitat.
Stygofauna are also susceptible to any changes in the chemistry of the groundwater. We simply do not know with confidence what mining will do to the groundwater chemistry at Yeelirrie in the long term. Various wastes will be backfilled into former pits, causing uncertainty for the welfare of surrounding stygofauna.
Read more:
Maybe we can, but should we? Deciding whether to bring back extinct species
The approval conditions suggest that the mine should not be allowed to cause extinction – but if this does happen, nothing can be done to reverse it. And there would be no penalty to Cameco either – which has said it can’t guarantee such a condition can be met.
So are the economic benefits worth wiping out a species?
Short answer: no. But let’s, for a moment, ignore these subterranean animals and look at whether the mine would be beneficial.
Yeelirrie is one of Australia’s largest uranium deposits – and yet it has a low grade of 0.15% (as uranium oxide). This refers to the amount of uranium found in rock. For comparison, the average grade of uranium mines globally is normally 0.1 to 0.4% of uranium oxide (with some higher and others lower).
And Cameco’s Cigar Lake and McArthur River mines in Canada have typically been 15-20% of uranium oxide. Despite such rich ore, McArthur River was uneconomic and closed indefinitely in early 2018.
What’s more, the future of nuclear power is not bright. According to the World Nuclear Industry Status Report, the number of nuclear reactors under construction around the world is at its lowest point in a decade, as renewable energy increases. The amount of nuclear electricity produced each year is flat. And nuclear’s share of global electricity is constantly falling behind renewables.
Read more:
Electric cars can clean up the mining industry – here’s how
But, in any case, we don’t yet know enough about these stygofauna to warrant their extinction. They could, for instance, have untold benefits to medical science, or perhaps have wider environmental and cultural significance.
And, ethically, what right do we have to wipe out a species? They have evolved and survived just like us. At the end of the day, there are much safer, cheaper, more ethical and cleaner ways to generate electricity to boil a kettle.
Gavin Mudd, Associate Professor of Environmental Engineering, RMIT University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Message to the EU: you have the chance to stop fuelling devastation in the Amazon
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Claire F.R. Wordley, University of Cambridge and Laura Kehoe, University of Oxford
The effects of European consumption are being felt in Brazil, driving disastrous deforestation and violence.
But the destruction can end if the European Union demands higher environmental standards on Brazilian goods. Hundreds of scientists and Indigenous leaders agree: the time to act is now, before it’s too late.
Read more:
Jair Bolsonaro can be stopped from trashing the Amazon – here’s how
In an open letter published today in the journal Science, more than 600 scientists from every country in the European Union (EU) and 300 Brazilian Indigenous groups asked the EU to demand tougher standards for Brazilian imports.
The letter calls on the EU to ensure a trade deal with Brazil respects human rights and the natural world.
Crucially, this can be done without harming Brazil’s agriculture, if already cleared land is used to its full potential. Indeed, in the long term, farming in the region depends on the rains brought by healthy forests.
Destruction of the Amazon under Bolsonaro
Brazil’s Indigenous people and the forests they protect are facing annihilation.
Controversial president Jair Bolsonaro is opening the Amazon rainforest to business and threatening Indigenous people who stand in the way. In his first hours in office, Bolsonaro gave power over Indigenous land to the Ministry of Agriculture, which is widely seen to be controlled by corporate lobbyists.
Read more:
Bolsonaro’s approval rating is worse than any past Brazilian president at the 100-day mark
In the months since, he has axed environmental roles in the government and planned three major building projects in the Amazon, including a bridge over the river itself.
As Bolsonaro scraps environmental laws, forests are being cut down faster than they have been in years. And the EU is helping drive this carnage: more than a football field of Brazilian rainforest is cut down every hour to produce livestock feed and meat for Europe.
Read more:
Amazon deforestation, already rising, may spike under Bolsonaro
Although the situation may seem dire for the Amazon and its inhabitants, ongoing trade talks provide a chance to act.
Billions of euros flow to Brazil from business with the EU, its second-largest trade partner. Goods flowing in the other direction include environmentally and socially destructive livestock feed (usually soy grown on deforested land) which enters the EU on a tariff-free basis. Right now, European consumers have no way of knowing how much blood is actually in their hamburger. The ongoing EU-Brazil trade talks are therefore a powerful opportunity to curb Bolsonaro’s appetite for destruction.
Laura Kehoe and Sara Lucena, Author provided
It is hard to overstate the case for strong action from Europe. People in Brazil – especially Indigenous and local communities – are being violently repressed when trying to defend their land against agricultural and mining companies.
Brutal repression and environmental catastrophe
This violence has reached record levels under Bolsonaro, with at least nine people murdered so far in April 2019. And genocide is a real possibility if nothing is done to protect Indigenous people and their land.
Alarmingly, Bolsonaro has even said:
It’s a shame that the Brazilian cavalry hasn’t been as efficient as the Americans, who exterminated the Indians.
On top of the horrifying assault on Brazil’s original inhabitants, demolishing the country’s forests, savannas and wetlands would have devastating consequences for the world.
If the Amazon rainforest alone is destroyed, the resulting carbon emissions could make it extremely difficult to limit global warming to less than two degrees. Burning fossil fuels is often seen as the only culprit in climate breakdown, but tropical deforestation is the second-largest source of carbon emissions in the world.
Mike Clark/GlobalForestWatch.org, Author provided
Even losing part of the Amazon could cause a tipping point where the forests no longer create enough rain to sustain themselves. This would cause droughts that would drive many species to extinction, devastate farming in the region and likely cause further violence.
We must act now
We are not just at an ecological tipping point, but a social one, too. The world is waking up to the risks posed by destroying our climate and natural world. Climate change is considered the number one security threat by Brazilian people and by many European nations.
Ryan Anderton/flickr, CC BY-NC-ND
Europeans believe neither their country nor the EU is doing enough to protect our planet’s life support systems. As protests flare up in Europe over environmental crises, climate change will be a key issue in the upcoming European elections.
Read more:
Strict Amazon protections made Brazilian farmers more productive, new research shows
As scientists, we use emotive words carefully. But our open letter calls on the EU to take urgent action because we are terrified of the consequences of Brazilian deforestation, both locally and globally.
We beg the EU to stand up for its citizens’ values and our shared future by making sure trade with Brazil protects, rather than destroys, the natural world on which we all depend.
Visit EUBrazilTrade.org for more information – including a list of parliamentary members standing in the European election who support this initiative. Register to vote in the EU elections here.
Claire F.R. Wordley, Research Associate in Conservation Evidence, University of Cambridge and Laura Kehoe, Researcher in Conservation Decision Science and Land Use, University of Oxford
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Bizarrely distributed and verging on extinction, this ‘mystic’ tree went unidentified for 17 years
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Gregory John Leach, Charles Darwin University
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Almost 30 years ago, the specimen of a weird tree collected in the southern part of Kakadu National Park was packed in my luggage. It was on its way to the mecca of botanical knowledge in London, the Royal Botanic Gardens Kew.
But what was it?
With unusual inflated winged fruits, it flummoxed local botanists who had not seen anything like it before. To crack the tree’s identity, it needed more than the limited resources of the Darwin Herbarium.
Later, we discovered a fragmentary specimen hidden in a small box at the end of a little-visited collection vault in the Darwin Herbarium. And it had been sitting there quietly since 1974.
Most of the specimens inside this box just irritate botanists as being somewhat intractable to identify. It’s known as the “GOK” box, standing for “God Only Knows”.
Together with the resources of Kew Gardens, the species was finally connected with a genus and recognised as a new species.
A year later, it was named Hildegardia australiensis.
The Conversation
Mysterious global distribution
The species is the only Australian representative for an international genus, Hildegardia. Under Northern Territory legislation, it’s listed as “near threatened”, due to its small numbers and limited distribution.
The genus Hildegardia was named in 1832 by Austrian botanists Schott and Endlicher. They named it after Hildegard, the 11th-century German abbess and mystic, the “Sybil of the Rhine”.
The genus retains some of this mystical and elusive nature. It’s rare with small isolated populations, traits that seem to dominate for all bar one of the species in the genus.
Twelve species of Hildegardia are recognised: one from Cuba, three from Africa, four from Madagascar and one each from India, the Philippines, Indonesia and Australia.
This bizarre global distribution is even more unusual in that almost the entire generic lineage seems to be verging on extinction.
The Australian species fits this pattern of small fragmented populations and, despite being a reasonably sized tree at up to 10 metres tall, remained unknown until 1991.
Rarely seen and hard to find
Generally, Hildegardia species are tall, deciduous trees of well-drained areas, often growing on rocky hills.
Their trunks have a smooth, thin bark, which smells unpleasant and exudes a gum when wounded. Most species have heart-shaped leaves and bear a profusion of orange-red flowers when leafless. These are followed by strange, winged fruits with one or two seeds.
Hildegardia australiensis would have to be one of the most rarely seen trees in Australia in its natural habitat. It is native to the margins of the western Arnhem Land Plateau with scattered populations on limestone and sandstone scree slopes.
These are all difficult locations to visit, so if you really want to see it, a helicopter is recommended. Fortunately it is easy to grow and has found its way into limited cultivation.
Several trees have been in the Darwin Botanic Gardens since the early ’90s and a few are known to have been planted in some of the urban parks in greater Darwin. The plantings have been more to showcase a rare and odd-looking tree rather than any great ornamental value.
Growing on ‘sickness country’
In the NT the tree is so poorly known that it has no common name other than the default generic name of Hildegardia.
It appears to have no recorded Indigenous uses, which is perhaps not surprising as much of its distribution is in “sickness country”.
This is country with uranium deposits and was avoided by the traditional owners. Rock art showing figures with swollen joints has been interpreted as showing radiation poisoning.
But it does have one claim to fame. A heated debate between conservationists and miners was sparked during a proposed development of the Coronation Hill gold, platinum and palladium mine in Kakadu National Park.
The main population of H. australiensis is only a stone’s throw from Coronation Hill and the species became one of the key identified biodiversity assets that could have been threatened by development of the mine.
The area around Coronation Hill, or Guratba in the local Jawoyn language, is also of considerable spiritual significance to the Jawoyn traditional landowners and forms part of the identified “sickness country”. A creation deity, Bula, rests and lays dormant under the sickness country and should not be disturbed.
Eventually, these concerns culminated in the Hawke government decision on June 17 1991 to no longer allow the mine development.
Read more:
The Price of God at Coronation Hill
So are the seeds edible?
While there appears to be no known uses of the Australian species, the tree may have hidden potential.
The closely related trees Sterculia and Brachychiton are well known as bush tucker plants and good sources of fibre. The local Top End species Sterculia quadrifida, for instance, is commonly known as the Peanut Tree and is a highly favoured bush tucker plant.
The fibre potential of H. australiensis is being explored by internationally acclaimed Darwin-based papermaker, Winsome Jobling. Cyclone Marcus whipped through Darwin in 2018 and one of the casualties was a planted tree of H. australiensis in the Darwin Botanic Gardens.
Thankfully, material was salvaged. Winsome has material stored in her freezer awaiting extraction and processing to see what the fibre potential is.
H. barteri, an African species in the Hildegardia genus, has a broad distribution through half-a-dozen African countries. And the West African locals have a number of uses for it, from eating the seeds to using the bark as fibre for ropes. But we don’t know just yet if the flesh or seed in the Australian species is edible.
Whether the Australian species might also harbour such useful properties still awaits some testing and research. Fortunately, with the creation deity Bula watching over the natural populations, the species, unlike many of its close relatives, appears secure in the wild.
Gregory John Leach, Honorary Fellow at Menzies School of Health Research, Charles Darwin University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Seychelles
London
Ditch plastic dog poo bags, go compostable
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M. Leigh Ackland, Deakin University
We humans have a habit of avoiding our waste. We find organic waste particularly unpleasant. We bag it and dispose of it as soon as possible.
Even the most environmentally conscious person would rather not handle something like decomposing food or dog poo with their bare hands. Plastic bags are often the first step we take to disconnect ourselves from our waste – until we can get rid of it somewhere else.
Traditional plastic bags are made from ethylene, derived from petroleum or natural gas. Ethylene does not degrade easily. So these types of bags are major contributors to plastic pollution.
More than three-quarters of plastic ends up in landfill, while up to 5% finds its way to the ocean. Only 9% of plastics are recycled.
Read more:
Is your dog happy? Ten common misconceptions about dog behaviour
Many environmentally conscious pet owners are turning to biodegradable bags as the solution to their doggy-doo woes, but many brands won’t break down in landfill, compounding the problem. Alternatives are at hand, though, with compostable bags and community sharing programs that can help non-composters.
A ‘biodegradable’ statement on a bag isn’t enough: it needs a logo
“Biodegradable” means something that can potentially be broken down naturally in the environment, particularly by microorganisms but also by other factors such as heat, light and oxygen. We usually think of biodegradable materials as derived from natural sources such as plants, but synthetic materials can also be biodegradable.
But there are issues with the term “biodegradable bag”. Bags can be labelled biodegradable, but after being used and discarded they might only partly decompose because the conditions are not right for full decomposition. Or else the decomposition might take a long time.
Full decomposition means complete conversion of the bag into simple substances such as carbon dioxide and water that can be re-used by microorganisms like bacteria and fungi.
Carol Von Canon/Flickr, CC BY-NC-SA
The biodegradability of plastic can be measured in a laboratory using methods such as carbon tracking. There are international standards for testing biodegradability of plastics. The International Organization for Standardization (ISO) has developed these standards.
Unfortunately, ocean and landfill environments are not conducive for degradation of biodegradable plastic. Marine environments often don’t contain the right types of microorganisms needed to break down plastics, or there aren’t enough to be effective in a reasonable time frame. Landfill conditions often lack oxygen, which limits the types of microorganisms that can exist there.
Compost, however, provides an ideal environment for biodegradation. Compost contains a diverse range of organic materials that support the growth of many different varieties of organisms.
DNA sequencing has revealed the huge diversity of microorganisms that exist in compost. These include bacteria, fungi and invertebrates that can digest a wide range of organic materials. In particular, fungi are found to possess enzymes that are capable of breaking down many different organic substances.
Compost to the rescue
You can now buy compostable bags. These are a type of biodegradable bag that is suitable for disposal in compost only (not in the ocean or landfill!).
How can you tell if a compostable bag can actually be fully broken down in compost? Standards Australia produces standards for the biodegradability of plastic bags. Code AS 4736-2006 specifies a biodegradable plastic that is suitable for overall composting (which includes industrial processes) and other microbial treatment, while AS 5810-2010 specifies home composting.
Standards Australia provide a brief overview of the testing carried out for AS 5810-2010. Other countries have similar standards – for example, the US has ASTM code D6400, which certifies that the material meets the degradation standard under controlled composting conditions.
The Australian Bioplastics Association administers a voluntary verification scheme. This enables manufacturers or importers to have their plastic materials tested and certified.
There is a double arrow logo you can watch out for on bags that have been certified as home compostable and there is a seedling logo for certified compostable. If you cannot locate a certified compostable bag in your area, you can source them online. Make sure they have have the certified compostable logo of the country from which they come.
It is interesting to observe the biodegradability of a plastic bag in your compost heap, as I did with a compostable bag full of dog poo. After two weeks buried in the compost, the only evidence of the bag was some small black fragments. These looked like leaf mould except they had the print from the bag label on them. In comparison, a normal plastic bag buried at the same time was completely unaltered. Of course, this experiment is not proof of total bag degradation – proper laboratory testing would be required for this.
Read more:
Are you walking your dog enough?
What if you can’t compost?
If you cannot compost, you will probably be relying on your local council to dispose of your waste. If the council uses landfill for waste disposal then there may be no point in using compostable bags for your waste, as landfill does not have the right conditions for composting to occur.
If you have a kerbside green waste collection that is composted, this service most likely will not accept food waste at the moment – which means dog poo is very unlikely to be included. Nor may compostable bags be allowed in green waste collections. Some councils, however, are working towards food organics/green organics waste collections for the future, and these may include compostable bags.
Moyne Shire in western Victoria, for instance, provides compostable bags for dog poo and accepts it along with green waste in its fortnightly “FOGO” collection.
If you have material for composting but do not have a compost heap, you can join Sharewaste. Sharewaste links people who want to recycle their organic waste with their neighbours who can use the waste for composting, worm farms or chickens. So this is a way to avoid sending your organic waste to landfill.
Composting your organic waste is like harvesting rain into your water tank or tapping into sunlight for your energy needs. These things are meaningful beyond their utility; they connect you to nature and give insights into the natural cycles of life on planet Earth.
M. Leigh Ackland, Professor in Molecular Biosciences, Deakin University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Kevin's Walk on the Wild Side 
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