The diet of invasive toads in Mauritius has some rare species on the menu

The invasive guttural toad.
Author supplied.

James Baxter-Gilbert, Stellenbosch University

The guttural toad (Sclerophrys gutturalis) is a common amphibian found in much of sub-Saharan Africa, from Angola to Kenya and down to eastern South Africa. With such a wide geographic range, and a liking for living in human-disturbed areas, it’s often seen in people’s backyards. Around gardens it can be thought of as a helpful neighbour, as it is a keen predator of insects and other invertebrates that may try to eat plants. Yet it also has the potential to be ecologically hazardous outside its native range – and this toad is an accomplished invader.

In the Mascarene Archipelago in the Indian Ocean, far from mainland Africa, these toads have been an established invasive species for almost 100 years. In 1922, the director of dock management in Port Louis, Mauritius, deliberately released guttural toads in an attempt to control cane beetles – a pest of the country’s major crop, sugar cane. This attempt at biocontrol failed, but the toads appeared to thrive and rapidly spread across the island.

Mauritius had no native amphibian species for it to compete with, and no native predators with a recent evolutionary history with toads. In mainland Africa these toads would have to divide resources, like food, with a host of native amphibians and deal with an array of native birds, mammals and snakes that evolved feeding on them. But without these challenges on Mauritius, the toads colonised the entire island rapidly.

Most toads are generalist predators and hunt a wide variety of prey, more or less eating whatever they can fit in their mouth. So as the guttural toad’s population numbers grew through the decades, so too did the concerns from Mauritian ecologists about the impact on native fauna. Anecdotal accounts as early as the 1930s suggest that the toads were having a negative impact on endemic invertebrate populations. In fact it has been suggested that the toads may have been a driver in the decline, and possible extinction, of endemic carabid beetles and snails.

But it’s only recently that the toad’s diet in Mauritius has been examined closely. In our new study we examined the stomach contents of 361 toads collected in some of the last remaining native forests of Mauritius.

By knowing more about what species the toads are eating, and which groups they favour, our research may help inform toad control actions to protect areas with known sensitive species.

In the belly of the beast

Through our research we were able to identify almost 3,000 individual prey items, encompassing a wide variety of invertebrates like insects, woodlice, snails, spiders, millipedes and earthworms.

This research also went one step further to examine the prey preference of the toads. In general, they seemed to favour, some of the more abundant and common prey species. These included ants and woodlice, which made up about two-thirds of their overall diet.

These findings may suggest that the toads were able to identify a readily available food source, and this may have fuelled their invasive population growth. Yet they are also eating prey that represents a more serious conservation concern.

Inside the toads we found 13 different species of native snail, most of which were island endemics. Four species are listed as being vulnerable to extinction and one, Omphalotropis plicosa, being critically endangered – having been presumed extinct until it was rediscovered in 2002. Understandably, we found it very troubling to find a “Lazarus species” within the stomach of an invasive predator.

Unanswered questions

These early insights into the native species now being hunted by a widespread and voracious predator raise new research questions. To understand the greater impact the toads are having on native species much more work is required to understand their prey’s population dynamics so we can determine if the toad’s invertebrate “harvest” is contributing to declines.

Furthermore, how does the toad’s invasive diet in Mauritius compare with that of other invasive populations, like those in Réunion or Cape Town – is their invasive success linked to a common prey type? And how does it compare with their diet in their own native species range?

Our study could only examine what they are eating currently, but Mauritius has seen numerous species decline over the past 100 years. What role did the toad play in these losses? Perhaps they historically fed more readily on creatures that were more abundant in the past, but had to switch their favour to ants and woodlice when the populations of other species dropped. We may never know.

What is clear is that there is much to learn about the habits of this far-from-home amphibian and its impact on the ecosystems it has invaded.

James Baxter-Gilbert, Postdoctoral Fellow, Centre for Invasion Biology (C·I·B), Department of Botany & Zoology, Stellenbosch University

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

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Think taxing electric vehicle use is a backward step? Here’s why it’s an important policy advance

Jago Dodson, RMIT University and Tiebei (Terry) Li, RMIT University

The South Australian and Victorian governments have announced, and New South Wales is considering, road user charges on electric vehicles. This policy has drawn scorn from environmental advocates and motor vehicle lobbyists who fear it will slow the uptake of less-polluting vehicles. But, from a longer-term transport policy perspective, a distance-based road user charge on electric vehicles is an important step forward.

Superficially, a charge on electric vehicle use seems misguided. Road sector emissions are the worst contributors to climate change. Electric vehicles powered by clean energy offer the promise of near-zero emissions.

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Read more:
Transport is letting Australia down in the race to cut emissions

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As electric vehicle and renewable energy costs decline we can expect a shift to full electrification of urban vehicles over the next 30 years. Surely accelerating this transition is an urgent climate task?

The downside lies not in the carbon benefits of these vehicles, but in their use as private passenger transport in congested urban areas and the costs this use imposes on cities. As renewable energy becomes cheaper, the marginal cost of every kilometre driven is likely to decline. As driving becomes cheaper, more of it is likely to occur.

More driving means more congestion. Inevitably, that increases demand for increasingly expensive road projects, such as Sydney’s WestConnex, or Melbourne’s Westgate Tunnel and North East Link. It certainly will run against the recognition in urban plans such as Plan Melbourne that we must shift to alternative transport modes.

If we don’t have a pricing regime that accounts for the cost of car use in cities, the transition to electric vehicles is likely to work against the wider goals of urban and transport policy.

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Cars rule as coronavirus shakes up travel trends in our cities

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How would distance-based charging work?

Many urban transport policy advocates have called for distance-based road-user charging to be imposed on all vehicles in cities. This sounds great in theory, but in practice is difficult for technical and political reasons of privacy and surveillance. Such concerns will diminish over time as cars increasingly incorporate automated telematics that necessarily track their movement.

Distance-based road-user charging efficiently matches road use to its costs – of infrastructure, congestion, noise, pollution and deaths. It improves on fuel excise, which drivers can nearly completely evade by using a highly efficient vehicle. It also goes beyond tolling to fund major roads, which typically apply only to specific links.

Second, road-user charging can be varied in response to demand that exceeds road capacities. Higher rates can be applied at peak times to ensure free-flowing traffic and shift travel to other times and modes. Various taxation reviews, including the 2009 Henry Taxation Review and Productivity Commission reports, have promoted such policies.

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Road user charging belongs on the political agenda as the best answer for congestion management

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Exactly how big would the disincentive be?

Would imposing such charges on electric vehicles retard their uptake?

Based on our work with ABS Census journey-to-work data, in Melbourne the average daily round-trip commuting distance by car is about 25 kilometres. The proposed Victorian charge is 2.5 cents per kilometre. Thus, in Melbourne the average daily commuter’s road user charge is likely to be 63 cents – $3.13 for a typical five-day working week. Over a 48-week working year that totals A$150, hardly a large sum for most people.

By comparison, a commuter in a conventional vehicle with the average current fuel efficiency of 10.9 L/100km will use about 2.73 litres of fuel on which they pay 42.3 cents per litre in fuel excise. That’s about $1.15 a day, or $5.75 a week.

The average tax saving for electric vehicles compared to conventional vehicles will be about 2.1 cents per kilometre. Electric vehicle drivers will be taxed about 53 cents a day, or $2.64 a week, less for their car work travel. They’ll be about $126 a year better off.

Commuting trips make up about 25% of car use, so electric car users’ overall savings are likely to be even greater.

It is difficult to see how such savings on excise tax are a disincentive to electric vehicle uptake. Fears of a “great big new tax”, as the Australia Institute puts it, seem unfounded, as are concerns that road-user charges would “slam the brakes on sales”.

Let’s be clear, the big barrier is the upfront cost of electric vehicles, about $10,000 more than their conventional equivalents. Advocates for electric vehicles should focus on that difference, and the failures in Australian government policy, not state road-user charges.

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Why taxing actual road use matters

It needs to be recognised that, with lower marginal costs, electric vehicles are likely to be used more than conventional cars. That would increase pressure on urban road capacity. So while the new road-user charge of 2.5 cents per kilometre is flat across the time of day or the route driven, this will likely need to change.

Distance-based road-user charges have been politically controversial. Imposing a tiny charge on a minority vehicle type is an expedient way of introducing a needed reform. Fewer than 1.8% of vehicles in Australia are currently electric or hybrid. But as all cars become electric, distance-based road charges will become an increasingly powerful policy tool.

Thanks to advancing telematics, transport planners will eventually be able to impose variable road-user charging by time of day and route, similar to ride-hailing companies’ “surge” pricing. We could then apply novel approaches such as a cap-and-trade system. A city could allocate its motorists an annual kilometres quota, which is then traded to create a market for excess urban road use.

The private car could also be integrated into mobility-as-a-service models.

Road-user charges could be regressive for people with few alternatives to the car. But telematic tracking could allow for lower charges for less affluent households in dispersed outer suburbs with few other options.

Beyond fuel, private cars have high environmental costs in steel, plastic, aluminium, glass and rubber use. And about one-third of our increasingly valuable urban space is given over to cars in the form of roads and parking.

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To reduce this demand on resources and space, car use could be priced to shift travel to, and fund, more sustainable and city-friendly modes such as public transport, walking and cycling. We could even price the car out of cities completely. The most environmentally sustainable car, after all, is no car at all.

Jago Dodson, Professor of Urban Policy and Director, Centre for Urban Research, RMIT University and Tiebei (Terry) Li, Research Fellow, School of Global, Urban and Social Studies, RMIT University

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

How green is your Christmas tree?

Paolo Paradiso / shutterstock

Ian D. Rotherham, Sheffield Hallam University

There’s no way around the fact that Christmas has a large carbon footprint, from the travelling we do to the presents we give and the large amounts of food we eat. But it is possible to at least reduce the negative impacts. With climate change and carbon dioxide levels now major sources of concern, surely it is time to see what can be done to be friendlier to the environment, and the Christmas tree is a good place to start.

As editor of an academic journal on arboriculture – the cultivation of trees – this is something I know a bit about. There are various aspects to assess: how the trees are grown, how many years they are used for, and how they are disposed of or recycled. For artificial trees, we also need to consider what they are made of and how and where they are manufactured.

For real trees, there is a question of where they comes from and how they were grown. Sourcing your tree locally will cut down on transportation costs and emissions and support local jobs too. Habitat may be another issue, since trees grown on moors, heaths, and peat bogs are hugely damaging with massive losses of peat-carbon and biodiversity, and increased downstream flooding. It’s better to instead choose trees grown on arable fields or “improved” grassland of little ecological interest.

Don’t worry about the emissions

When buying a Christmas tree, people may worry about carbon dioxide released back into the atmosphere when it is cut down and then, once used, disposed of. But there are issues and complications with this. Yes, you are cutting down a young tree which will either be thinned from a plantation of larger trees or be part of a single-aged crop all cut down at the same time. In the first instance, the loss of your tree will make no difference whatsoever to the carbon balance of the plantation since the other trees nearby will grow in compensation because competition for light and nutrients is reduced.

Even when a tree has been harvested as part of a single-aged crop, a proportion of its organic matter (and carbon) will remain as the dead root material and fallen leaves to be reincorporated into the soil’s carbon-bank. And if you recycle the tree after use as woodchip, then all that material is returned to the soil as well, and only a small proportion will return immediately to the atmosphere.

If you burn the old tree, then clearly both carbon dioxide and other pollutants go immediately into the air. However, even in this scenario, your tree can only return to the atmosphere the carbon which it took out in the first place – so there is zero net carbon loss. Our real concerns for carbon release are from burning of fossil fuels from below ground, and from damage to long-term carbon storage in peat bogs and fens. Disposal at landfill is much more damaging than incineration.

There is not much to choose between the different species of Christmas tree, at least in terms of carbon impact. There are issues, though, in terms of how trees are grown and particularly the use of pesticides in their cultivation, and potential damage to precious wildlife habitats. A recent example is the damage wrought to a peat bog in Cumbria by inappropriate planting of conifer trees.

An artificial tree, on the other hand, can have a relatively significant carbon footprint depending on what it is made from, and most of all, how many years it remains in service. Spread over ten years, the impact is negligible, but if it has been manufactured abroad, then the immediate carbon footprint is considerable.

How to reduce your tree’s footprint:

1) Buy a real tree, put it in a pot and use it over several years and finally plant it outside to live on. That way you will even mop up a little of your carbon footprint from other Christmas celebrations.

2) Recycle your real tree after use as woodchip or compost. Don’t bin or burn it.

3) Buy local and from a charity.

4) Avoid trees brought in from a distance and especially from an environmentally damaging source – ask the retailer where they are from. Better still, go direct to a local farm shop or National Trust site that is both producing and selling trees.

5) Ask for organically grown trees if possible.

6) Some growers make a donation per tree to an environmental charity – so ask when you buy.

Any “consumption” of goods has environmental impacts, but that is an unavoidable part of life. Christmas trees provide lots of pleasure for many people – just try to boost the good aspects and avoid or minimise the bad ones.

Ian D. Rotherham, Professor of Environmental Geography and Reader in Tourism and Environmental Change, Sheffield Hallam University

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

Why microplastics found in Nigeria’s freshwaters raise a red flag

Plastic pollution remains a topmost environmental concern
Pius Utomi Ekpei/AFP via Getty Images

Emmanuel O. Akindele, Obafemi Awolowo University

Freshwater ecosystems are a priority for environmental scientists because they affect the health of animals and plants on land too – as well as people. They provide food, water, transport and flood control. Freshwater ecosystems also keep nutrients moving among organisms and support diverse forms of life.

Freshwater systems make a big difference to the quality of life in any human society. But they are under great pressure. Freshwater biodiversity is declining faster than terrestrial biodiversity.

Among the three major types of habitats – terrestrial, freshwater and marine – freshwater accounts for less than 1% of the earth’s surface. Yet these habitats support more species per unit area and account for about 6% of the world’s biodiversity.

One of the biggest stresses on freshwater ecosystems is the presence of plastics. Some microplastics – tiny pieces of plastic that have broken down from bigger pieces – get into water from various sources. Some are introduced from industrial sources like cosmetics, toothpaste and shaving cream. Another major source is dumping of plastic waste like bags and bottles.

In Nigeria, an important source is the plastic sachets that contain drinking water. Over 60 million of these are consumed in a day.

Ultimately all these types of plastic waste find their way to the aquatic environment. There they stay in the water column, settle on river beds or are ingested by aquatic animals.

My research group set out to assess the load and chemical nature of microplastics in two important rivers and Gulf of Guinea tributaries in Nigeria. We looked for the presence of microplastics in aquatic insects since they often dominate aquatic animal life. Most also spend their adult stage in the terrestrial environment, once they emerge from their larvae. We found that microplastics were present in large quantities in the insect larvae. The insects are part of a food chain and could transfer the harmful effects of microplastics throughout the chain.

This further reinforces the urgent need for Nigeria to go ahead with measures to reduce the use of plastic bags and single-use plastics.

The research findings

We used three of the rivers’ aquatic insect species as bio-indicators and found that all three had ingested microplastics from the two rivers. The ingested microplastics include styrene-ethylene-butylene-styrene, acrylonitrile butadiene styrene, chlorinated polyethylene, polypropylene, and polyester. The quantity of microplastics ingested by the insects was fairly high, especially in the Chironomus sp. which is a riverbed dweller recorded in the Ogun River.

The diversity of plastic polymers recorded in these insects suggests a wide range of applications of plastics in Nigeria.

The three insect species spend their larval stages in the water and later migrate to land in the adult phase. The concern is that the insect larvae could serve as a link for microplastics’ transfer to higher trophic levels in the aquatic environment. Also, the adults serve in the same capacity in the terrestrial environment. A trophic level is the group of organisms within an ecosystem which occupy the same level in a food chain.

Dragonfly larvae in the water are eaten by fish, salamanders, turtles, birds and beetles. Adult dragonflies on land are also eaten by birds and other insects.

Other research elsewhere has shown the link between microplastics and human health.

Through feeding, the transfer of microplastics in the environment could go as far as people – who caused the plastic pollution in the first place.

Evidence suggests that microplastics reduce the physiological fitness of animals. This comes through decreased food consumption, weight loss, decreased growth rate, energy depletion and susceptibility to other harmful substances. Human health could similarly be at risk on account of microplastic ingestion.

Microplastics can be retained for a longer time at the higher trophic levels where humans belong, thereby predisposing humans to serious health hazards.

Case for a plastic bags ban

A ban on plastic bags would curb the plastic pollution in Nigeria. There are alternatives to the use of plastic bags, for instance, bags made from banana stalks, coconut, palm leaf, cassava flour and chicken feathers. Unlike plastic bags, which could persist in the environments for over a century, bags made from these organic materials decompose readily in a manner that does not pose a health risk to the environment.

For a long while, the call to mitigate plastic pollution was not heeded in Nigeria. Recently, the House of Representatives passed a bill banning plastic bags. But this is yet to be implemented as the president has not assented to it.

A study in the European Union indicates that a ban on single-use plastics could reduce marine plastic pollution by about 5.5%.

It is about time Nigeria treated plastic pollution as a national emergency, considering its implications for human health and the ecological integrity of aquatic ecosystems. An approach that puts people at the centre of the issue has been suggested as one way to convince local communities to preserve the integrity of the environment.

Perhaps this approach could help restore plastic-laden aquatic ecosystems and preserve the pristine ones.

Emmanuel O. Akindele, Senior Lecturer, Obafemi Awolowo University

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

Daytime sightings of elusive aardvarks hint at troubled times in the Kalahari

Disappearance of aardvarks from dry ecosystems could have devastating consequences for the many other animals that rely on their burrows.
Kelsey Green

Robyn Hetem, University of the Witwatersrand and Nora Marie Weyer, University of the Witwatersrand

Aardvarks are notoriously elusive, nocturnal mammals. They generally hide in their underground burrows during the day and emerge at night to feed exclusively on ants and termites. Aardvarks are widespread throughout most habitats of Africa south of the Sahara, except deserts. But their actual numbers are not known because they’re so elusive.

Aardvarks top the bucket list of many wildlife enthusiasts, but few have been fortunate enough to see them – until recently. Daytime sightings of aardvarks are becoming more common in the drier parts of southern Africa. But seeing them in the daytime does not bode well because it indicates they might not be finding enough food.

To understand how aardvarks cope with hot and dry conditions, we studied them in the Kalahari, one of the hottest and driest savannah regions in southern Africa in which aardvarks occur. Our study took place at Tswalu, a private reserve in South Africa that supports research through the Tswalu Foundation. We equipped wild, free-living aardvarks with biologgers (minicomputers) that remotely and continuously recorded their body temperature (an indicator of well-being in large mammals), and their activity. Each aardvark also received a radio-tracking device, allowing us to locate them regularly. Tracking the aardvarks provided clues on how they changed their behaviour in relation to environmental stressors in the different seasons and years of our three-year study.

Our study found that in drought periods, aardvarks struggled to find food. It was difficult for them to maintain their energy balance and stay warm during the cool night, so they shifted their active time to the day. Some died from starvation. Given the aardvark’s importance to ecosystems, these findings are a concern.

Aardvarks usually emerge from their burrows at night (left), but during drought periods, they are increasingly seen during daytime (right).
N. Weyer

Aardvarks are important ecosystem engineers

No other mammal in Africa digs as many large burrows as the aardvark. Dozens of mammals, birds and reptiles use aardvark burrows as shelter from extreme heat and cold, protection from predators, or a place to raise their young. In many of South Africa’s conservation areas, temperatures have already risen by 2℃ over the past 50 years. Further warming by 4-6℃ by the end of the century has been projected.

With deserts and drylands expanding across much of Africa, climate change might threaten the aardvark itself as well as the many animals reliant on aardvark burrows as a cool shelter from rising temperatures.

During typical years, aardvarks were active at night and were able to regulate their body temperature between 35-37℃.

Aardvark active at night during non-drought times.
adapted from Weyer et al., 2020, Frontiers in Physiology, https://doi.org/10.3389/fphys.2020.00637

However, this pattern changed during two severe summer droughts that occurred in the Kalahari during our study. During the droughts, aardvarks shifted their activity to the daytime and their body temperature plummeted below 30°C.

Using remotely-sensed vegetation data recorded by NASA satellites and our own camera trap footage and logger data, we showed that these dramatic changes in body temperature and activity of aardvarks were related to the availability of grass, on which their ant and termite prey rely. When grass was scarce during droughts, the ant and termite prey became inaccessible to aardvarks, preventing them from meeting their daily energy requirements. As their body reserves declined, aardvarks were unable to sustain the energy costs of maintaining warm and stable body temperatures and shifted their activity to the warmer daytime.

Aardvark active in the daytime during drought.
adapted from Weyer et al., 2020, Frontiers in Physiology, https://doi.org/10.3389/fphys.2020.00637

Shifting activity to the warmer daytime while food is scarce can save energy that would otherwise be spent on staying warm during cold nights. But, for our aardvarks, even these energy savings were insufficient during drought, when the ground was bare and the ant and termite prey inaccessible. As a result, seven of our twelve study aardvarks and many others died, presumably from starvation.

A bleak future for aardvarks in a hotter and drier world

On the Red List of Species of the International Union for Conservation of Nature, aardvarks are currently categorised as a species of “Least Concern”. However, we consider aardvarks to be threatened in the drier parts of their distribution in Africa, such as the Kalahari, where climate change brings about droughts. Disappearance of aardvarks from these ecosystems could have devastating consequences for the many other animals that rely on the aardvarks’ burrows.

We hope that our findings will raise further awareness about the consequences of climate change and inform future wildlife conservation and management decisions. Such steps might include assessments of the actual population status of aardvarks across Africa, or mitigation measures to preserve species that depend on burrows for refuge in regions where aardvarks might go locally extinct. More extensive measures, like water-wise reserve management, increasing sizes and connectivity of nature reserves in semi-arid regions, and reducing emissions to mitigate climate change, are just as urgent.

Finally, any solution to the plight of climate change on free-living animals requires a better understanding of their capacities to cope with drought. Therefore, many more long-term comprehensive studies are needed on the physiology and behaviour of the vulnerable animals living in hot, arid regions of the world.

Nora Marie Weyer’s disclosure statement has been updated.

Robyn Hetem, Senior Lecturer, University of the Witwatersrand and Nora Marie Weyer, PhD – Wildlife Conservation Physiology, University of the Witwatersrand

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

Fires shaped Mount Kilimanjaro’s unique environment. Now they threaten it

Fires on Kilimanjaro, October 2020.
Thomas Becker/picture alliance via Getty Images

Andreas Hemp, Bayreuth University

In October, firefighters in Tanzania had to tackle a number of fires on Mount Kilimanjaro, Africa’s tallest mountain and the largest free-standing mountain in the world. The mountain and surrounding forests fall into Kilimanjaro National Park, named a UNESCO World Heritage site in 1987. Andreas Hemp provides a glimpse into the mountain’s natural environment and the challenges it faces.

Is this the first time there has been a fire of this magnitude? If there have been fires like this before, what damage was done to the mountain’s vegetation and how long did it take it to recover?

Fires are quite common in the higher areas of Kilimanjaro at the end of the dry seasons, around February to March and September to October. Fire can transform land cover, but it also maintains it. Studies that I’ve done with colleagues (using pollen records buried in the soil that go back 50,000 years) showed that fires always played a role in shaping the vegetation belts on the mountain.

For instance, certain species, such as the giant groundsels (Dendrosenecio) became fire-adapted. Also, without fires opening up the forests many light demanding species, such as the famous giant lobelias, would not be able to grow.

There have, however, been several severe fires on Kilimanjaro over the last few decades that have dramatically changed land cover.

Fires in 1996 and 1997 – years with unusually dry seasons – destroyed vast areas of old cloud forest. These are characteristically moist forests in high altitude areas which create unique environments. The forest was replaced by bush. Vegetation has started to recover and shrubs have sprouted, but it’s far from being a forest, which would take at least 100 years to grow without fire. Since these old forests have an important function of fog water collection, the loss of these forests means a serious impact on the water balance of the mountain, much larger than the impact of the melting glaciers, which is ecologically negligible.

The impact of these former fires was much bigger than that of the recent one, which “only” affected bush land and not forest.

What type of vegetation exists on Mt Kilimanjaro and how unique is it?

Due to its enormous height, Kilimanjaro has several distinct vegetation belts.

It is surrounded on the foothills by cultivation with a unique mix of agriculture, savanna and forest. This harbours very rich biodiversity as well as the tallest trees on the continent.

Higher up the mountain – between about 1,800 and 3,000 metres – a montane forest belt encircles the whole mountain. This is one of the largest forest blocks in East Africa.

Even higher up, between 3,000 and 4,000 metres, there’s a heathland belt typical of the high mountains in East Africa. This vegetation consists of Erica, Protea, Stoebe and many other shrub species, many of them are endemic, occurring only on one or several mountains.

Erica shrubs burn very easily, which makes this vegetation belt particularly flammable. During wet periods without fire, the former forest can re-establish and expand to the tree line at 4000m. During dry periods, with recurring fires (natural and or caused by people), the forest belt shrinks and the ericaceous belt expands.

What challenges does the mountain’s natural environment face and have there been any noticeable changes over the years?

Over the last 150 years, the regional climate has become drier. This has caused the mountain’s glaciers to shrink by almost 90% of their former extent. The drier climate is also the reason for an increase in the frequency and intensity of wild fires in the upper areas of Kilimanjaro, affecting the forests.

Most of these fires are lit by people (such as honey collectors smoking out bees), but these fires would not have been so devastating if the climate was wetter.

There’s an interplay between direct anthropogenic (caused by people) and climatic impacts.

Since 1911 the human population on Kilimanjaro has increased from 100,000 to over 1.2 million. This has resulted in an enormous loss of natural vegetation. Kilimanjaro is becoming an ecological island, isolated and surrounded by agriculture. Over this period it has lost 50% of its forest cover. In the lower areas this is mainly due to logging and clearing. In the upper areas it’s due to fires.

In combination with global climate change, this forest destruction results in a decrease of moisture in the region. This will also affect agriculture in the region because it’s partly irrigated.

Who is responsible for protecting the mountain and how well protected is it?

In 2005, the forest belt was incorporated into the mountain’s existing national park area. This means that it falls under the responsibility of the Tanzania and Kilimanjaro National Park authorities. The forest belt is much better protected than it was before, as a forest reserve.

The banning of camp fires on the tourist routes by the national park authorities helped to reduce the fire risk. But it’s not possible to exclude the risk in this large heathland belt totally. Perhaps the acquisition of larger fire-fighting airplanes could help. Fires are usually fought by hundreds of volunteers and firefighters, using shovels and machetes creating fire breaks by hand. This recent fire was the first time that a helicopter was used to carry water from nearby dams.

What else can be done?

To protect the biodiversity of Kilimanjaro the unique forests of the larger deep river valleys below the National Park should be incorporated into the National Park. Kilimanjaro is becoming an ecological island completely isolated and surrounded by agriculture. This inhibits the exchange of animal populations and affects biodiversity.

It’s all the more important that the wildlife corridor connecting the Amboseli ecosystem in Kenya and Kilimanjaro National Park has to be well protected. It is under great pressure due to grazing and agriculture. This corridor is important for the migration of elephants, which stay now more and more on Kilimanjaro destroying the forest.

Andreas Hemp, Research Associate Plant Systematics, Bayreuth University

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

Planning a road trip in a pandemic? 11 tips for before you leave, on the road and when you arrive

Shutterstock

Thea van de Mortel, Griffith University

As restrictions ease around the country and the prospect of travel beckons, many of us will be planning road trips for the holiday season.

To ensure your trip is memorable in the best rather than the worst way, here are some things you and your fellow travellers can do to reduce the risk of becoming infected with, or spreading, COVID on your trip.

Before you go

1. Check for any travel or other COVID-specific restrictions or rules in the areas you will be travelling through or to, before you go. These can change rapidly and may include restrictions on how far you can travel, how many people per square metre are allowed in public spaces, and whether you need border passes or to wear a mask. Each state or territory has its own health department or government COVID website you can check.

2. Don’t take COVID with you. If anyone in your group has COVID-like symptoms, however mild, it is important to be tested and cleared for COVID before leaving. Common symptoms may include fever or chills, muscle aches, sore throat, cough, runny nose, difficulty breathing, new loss of taste or smell, and vomiting or diarrhoea.

3. Pack masks, disinfectant wipes and hand sanitiser. The two most likely ways of catching COVID are inhaling viral particles an infected person sheds when they cough, sneeze, laugh, talk or breathe; and ingesting particles by touching contaminated objects and then touching your face or food. Masks (and social distancing) can help reduce the former risk, while avoiding touching your face, frequent hand hygiene and cleaning surfaces can reduce the latter. So pack masks, wipes and hand sanitiser. Hand sanitiser should contain at least 60% alcohol.

4. Pack your own pillows and linen. We know people infected with SARS-CoV-2, the virus that causes COVID, can shed virus onto linen and pillows (and other surfaces), even when asymptomatic. We also know respiratory viruses can penetrate pillow covers and get into the microfibre stuffing. So you might want to consider bringing your own pillows and linen.

On your trip

5. Use disinfectant wipes to clean high-touch surfaces in your hire car. These would include door and window handles or buttons, light switches, seat adjuster controls, radio controls, the steering wheel, glove box button, gear/drive and handbrake levers, rear-view mirrors and mirror controls.

6. How about singing in the car? The more vigorous the activity, the greater the opportunity to release droplets and aerosols and the further these will travel. So, laughing and singing will release more of these than talking, and talking will release more than breathing. However, if you are travelling in a family group, or with your housemates, then you have been in close contact with one another at home and the additional risk would be low.

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7. Maintain social distancing at service stations. Leave at least 1.5 metres between you and the next person while paying for fuel, ordering food and when using the bathroom. Make sure you wash or sanitise your hands after touching surfaces such as petrol pumps, door handles, bathroom taps, and before getting back in your car.

Wash or sanitise your hands after using the petrol pump.
Shutterstock

8. Pay with cards rather than cash to avoid touching money. Many people can handle bills and coins over a long duration of time, providing many opportunities to transfer disease-causing microbes from one person to the next. Using contactless payment also helps maintain social distancing.

9. It’s safer to eat outdoors than indoors if stopping for a snack or lunch. That’s because large volumes of air dilute the density of viral particles in the air. Evidence from a study of COVID clusters in Japan suggests the chance of transmitting COVID is more than 18 times higher inside than outside.

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How to stay safe in restaurants and cafes

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When you arrive

10. Is your hotel or rented accommodation COVID-safe? Ask the accommodation provider what steps they have taken to make the place less conducive to spreading COVID. For example, have they introduced extra cleaning or disinfection?

11. Use disinfectant wipes in rented accommodation to clean high-touch surfaces such as door handles, light switches, cupboard handles, taps and toilet flush buttons. You can also put dishes and cutlery through the dishwasher on a hot cycle. This is because the virus can remain viable (able to cause infection) on surfaces for many days.

Following these simple steps can help to keep your trip memorable in the best possible way. Happy holidays!

Thea van de Mortel, Professor, Nursing and Deputy Head (Learning & Teaching), School of Nursing and Midwifery, Griffith University

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

How will sharks respond to climate change? It might depend on where they grew up

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Culum Brown, Macquarie University and Connor Gervais

They may have been around for hundreds of millions of years — long before trees — but today sharks and rays are are among the most threatened animals in the world, largely because of overfishing and habitat loss.

Climate change adds another overarching stressor to the mix. So how will sharks cope as the ocean heats up?

Our new research looked at Port Jackson sharks to find out. We found individual sharks adapt in different ways, depending where they came from.

Port Jackson sharks in Jervis Bay may be better at responding to climate change than those from The Great Australian Bight.
Connor Gervais, Author provided

Port Jackson sharks from cooler waters in the Great Australian Bight found it harder to cope with rising temperatures than those living in the warmer water from Jervis Bay in New South Wales.

This is important because it goes against the general assumption that species in warmer, tropical waters are at the greatest risk of climate change. It also illustrates that we shouldn’t assume all populations in one species respond to climate change in the same way, as it can lead to over- or underestimating their sensitivity.

But before we explore this further, let’s look at what exactly sharks will be exposed to in the coming years.

An existential threat

In Australia, the grim reality of climate change is already upon us: we’re seeing intense marine heat waves and coral bleaching events, the disappearance of entire kelp forests, mangrove forest dieback and the continent-wide shifting of marine life.

The southeast of Australia is a global change hotspot, with water temperatures rising at three to four times the global average. In addition to rising water temperatures, oceans are becoming more acidic and the amount of oxygen is declining.

Any one of these factors is cause for concern, but all three may also be acting together.

Oceans act like a heat sink, absorbing 90% of the heat in the atmosphere. This makes marine environments highly susceptible to climate change.
Shutterstock

One may argue sharks have been around for millions of years and survived multiple climate catastrophes, including several global mass extinctions events.

To that, we say life in the anthropocene is characterised by changes in temperature and levels of carbon dioxide on a scale not seen for more than three million years.

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Rapid climate change represents an existential threat to all life on Earth and sharks can’t evolve fast enough to keep up because they tend to be long-lived with low reproductive output (they don’t have many pups). The time between generations is just too long to respond via natural selection.

Dealing with rising temperatures

When it comes to dealing with rising water temperature, sharks have two options: they can change their physiology to adapt, or move towards the poles to cooler waters.

Moving to cooler waters is one of the more obvious responses to climate change, while subtle impacts on physiology, as we studied, have largely been ignored to date. However, they can have big impacts on individual, and ultimately species, distributions and survival.

Juvenile Port Jackson sharks from our study.
Connor Gervais, Author provided

We collected Port Jackson sharks from cold water around Adelaide and warm water in Jervis Bay. After increasing temperatures by 3℃, we studied their thermal limits (how much heat the sharks could take before losing equilibrium), swimming activity and their resting metabolic rate.

While all populations could adjust their thermal limits, their metabolic rate and swimming activity depended on where the sharks were originally collected from.

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With a rise in water temperature of just 3℃, the energy required to survive is more than twice that of current day temperatures for the Port Jackson sharks in Adelaide.

The massive shift in energy demand we observed in the Adelaide sharks means they have to prioritise survival (coping mechanisms) over other processes, such as growth and reproduction. This is consistent with several other shark species that have slower growth when exposed to warmer waters, including epaulette sharks and bonnethead sharks.

The smaller egg to the left is from Port Jackson sharks near Adelaide, while the right egg is from sharks in Jervis Bay.
Connor Gervais, Author provided

On the other hand, a 3℃ temperature rise hardly affected the energy demands of the Port Jackson sharks from Jervis Bay at all.

Threatening the whole ecosystem

Discovering what drives responses to heat is important for identifying broader patterns. For example, the decreased sensitivity of the Jervis Bay sharks likely reflects the thermal history of the region.

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Sharks: one in four habitats in remote open ocean threatened by longline fishing

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Australia’s southeastern coastline is warmed by the East Australian Current, which varies in strength both throughout the year and from year to year. With each generation exposed to these naturally variable conditions, populations along this coastline have likely become more tolerant to heat.

Populations in the Great Australian Bight, in contrast, don’t experience such variability, which may make them more susceptible to climate change.

So why is this important? When sharks change their behaviour it affects the whole ecosystem.

The implications range from shifts in fish stocks to conservation management, such as where marine reserves are assigned.

Sharks and rays generally rank at the top or in the middle of the food chain, and
have critical ecosystem functions.

Port Jackson sharks, for example, are predators of urchins, and urchins feed on kelp forests — a rich habitat for hundreds of marine species. If the number of sharks decline in a region and the number of urchins increase, then it could lead to the loss of kelp forests.

Port Jackson sharks feed on feed on urchins in kelp forests.
Connor Gervais, Author provided

What’s next?

There’s little research dedicated to understanding how individuals from different populations within species respond to climate change.

We need more of this kind of research, because it can help identify hidden resilience within species, and also highlight populations at greatest risk. We have seen this in action in coral bleaching events in different parts of Australia, for example.

We also need a better handle on how a wide range of species will respond to a changing climate. This will help us understand how communities and ecosystems might fragment, as each ecosystem component responds to warming in different ways and at different speeds.

Steps need to be taken to address these holes in our knowledge base if we’re to prepare for what follows.

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One-fifth of ecosystems in danger of collapse – here’s what that might look like

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Culum Brown, Professor, Macquarie University and Connor Gervais, Connor Gervais

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

Not just hot air: turning Sydney’s wastewater into green gas could be a climate boon

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Bernadette McCabe, University of Southern Queensland

Biomethane technology is no longer on the backburner in Australia after an announcement this week that gas from Sydney’s Malabar wastewater plant will be used to power up to 24,000 homes.

Biomethane, also known as renewable natural gas, is produced when bacteria break down organic material such as human waste.

The demonstration project is the first of its kind in Australia. But many may soon follow: New South Wales’ gas pipelines are reportedly close to more than 30,000 terajoules (TJs) of potential biogas, enough to supply 1.4 million homes.

Critics say the project will do little to dent Australia’s greenhouse emissions. But if deployed at scale, gas captured from wastewater can help decarbonise our gas grid and bolster energy supplies. The trial represents the chance to demonstrate an internationally proven technology on Australian soil.

The project would turn Sydney’s sewage into a renewable gas.
Shutterstock

What’s the project all about?

Biomethane is a clean form of biogas. Biogas is about 60% methane and 40% carbon dioxide (CO₂) and other contaminants. Turning biogas into biomethane requires technology that scrubs out the contaminants – a process called upgrading.

The resulting biomethane is 98% methane. While methane produces CO₂ when burned at the point of use, biomethane is considered “zero emissions” – it does not add to greenhouse gas emissions. This is because:

• it captures methane produced from anaerobic digestion, in which microorganisms break down organic material. This methane would otherwise have been released to the atmosphere

• it is used in place of fossil fuels, displacing those CO₂ emissions.

Biomethane can also produce negative emissions if the CO₂ produced from upgrading it is used in other processes, such as industry and manufacturing.

Biomethane is indistinguishable from natural gas, so can be used in existing gas infrastructure.

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Biogas: smells like a solution to our energy and waste problems

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The Malabar project, in southeast Sydney, is a joint venture between gas infrastructure giant Jemena and utility company Sydney Water. The A$13.8 million trial is partly funded by the federal government’s Australian Renewable Energy Agency (ARENA).

Sydney Water, which runs the Malabar wastewater plant, will install gas-purifying equipment at the site. Biogas produced from sewage sludge will be cleaned and upgraded – removing contaminants such as CO₂ – then injected into Jemena’s gas pipelines.

Sydney Water will initially supply 95TJ of biomethane a year from early 2022, equivalent to the gas demand of about 13,300 homes. Production is expected to scale up to 200TJ a year.

The project involves cleaning and upgrading biogas from the Malabar Wastewater Treatment Plant.
Sydney Water

Biomethane: the benefits and challenges for Australia

A report by the International Energy Agency earlier this year said biogas and biomethane could cover 20% of global natural gas demand while reducing greenhouse emissions.

As well as creating zero-emissions energy from wastewater, biomethane can be produced from waste created by agriculture and food production, and from methane released at landfill sites.

The industry is a potential economic opportunity for regional areas, and would generate skilled jobs in planning, engineering, operating and maintenance of biogas and biomethane plants.

Methane emitted from organic waste at facilities such as Malabar is 28 times more potent than CO₂. So using it to replace fossil-fuel natural gas is a win for the environment.

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It’s also a win for Jemena, and all energy users. Many of Jemena’s gas customers, such as the City of Sydney, want to decarbonise their existing energy supplies. Some say they will stop using gas if renewable alternatives are not found. Jemena calculates losing these customers would lose it A$2.1 million each year by 2050, and ultimately, lead to higher costs for remaining customers.

The challenge for Australia will be the large scale roll out of biomethane. Historically, this phase has been a costly exercise for renewable technologies entering the market.

Biomethane will be injected into the existing gas network and delivered to homes.
Shutterstock

The global picture

Worldwide, the top biomethane-producers include Germany, the United Kingdom, Sweden, France and the United States.

The international market for biomethane is growing. Global clean energy policies, such as the European Green Deal, will help create extra demand for biomethane. The largest opportunities lie in the Asia-Pacific region, where natural gas consumption and imports have grown rapidly in recent years.

Australia is lagging behind the rest of the world on biomethane use. But more broadly, it does have a biogas sector, comprising than 240 plants associated with landfill gas power units and wastewater treatment.

In Australia, biogas is already used to produce electricity and heat. The step to grid injection is sensible, given the logistics of injecting biomethane into existing gas infrastructure works well overseas. But the industry needs government support.

Last year, a landmark report into biogas opportunities for Australia put potential production at 103 terawatt hours. This is equivalent to almost 9% of Australia’s total energy consumption, and comparable to current biogas production in Germany.

The distribution of reported operational biogas upgrading units in the IEA Bioenergy Task 37-member countries.

Current use of biogas in Australia.

A clean way to a gas-led recovery

While the scale of the Malabar project will only reduce emissions in a small way initially, the trial will bring renewable gas into the Australia’s renewable energy family. Industry group Bioenergy Australia is now working to ensure gas standards and specifications are understood, to safeguard its smooth and safe introduction into the energy mix.

The Morrison government has been spruiking a gas-led recovery from the COVID-19 recession, which it says would make energy more affordable for families and businesses and support jobs. Using greenhouse gases produced by wastewater in Australia’s biggest city is an important – and green – first step.

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Bernadette McCabe, Professor and Principal Scientist, University of Southern Queensland

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

Drones, detection dogs, poo spotting: what’s the best way to conduct Australia’s Great Koala Count

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Romane H. Cristescu, University of the Sunshine Coast; Celine Frere, University of the Sunshine Coast, and Desley Whisson, Deakin University

Federal environment minister Sussan Ley this week announced A$2 million for a national audit of Australia’s koalas, as part of an A$18 million package to protect the vulnerable species.

The funding might seem like a lot – and, truth be told, it is more than most threatened species receive. But the national distribution of koalas is vast, so the funding equates to about A$1.40 to survey a square kilometre. That means the way koalas are counted in the audit must be carefully considered.

Koalas are notoriously difficult to detect, and counts so far have been fairly unreliable. That can make it hard to get an accurate picture of how koalas are faring, and to know where intensive conservation effort is needed – especially after devastating events such as last summer’s bushfires.

Methods for counting koalas range from the traditional – people at ground level looking up into the trees – to the high-tech, such as heat-seeking drones. So let’s look at each method, and how we can best get a handle on Australia’s koala numbers.

Environment Minister Sussan Ley has pledged $2 million for a national koala count.
Glenn Hunt/AAP

Why we need to know koala numbers

Gathering data about species distribution and population size is crucial, because governments use it to assess a species’ status and decide what protection it needs.

In announcing the funding, Ley said the new audit aims to fill data gaps, identify where koala habitat can be expanded, and establish an annual monitoring program.

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So far, population estimates for koalas at the state and national level are rare and highly uncertain. For example, the last national koala count in 2012 estimated 33,000-153,000 in Queensland, 14,000–73,000 in NSW and 96,000-378,000 in the southern states.

This uncertainty can make it hard to detect changes in population trends quickly enough to do something about the threat, such as by limiting development or logging. However, the new audit can use methods not available in 2012, which should help with accuracy.

To date, estimates of koala numbers have been highly uncertain.
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So how do you actually count koalas?

Finding a koala can be difficult. There may be few individuals spread over large areas. And koalas are well camouflaged and quiet, unless bellowing. Finally, they can sit high in the tree canopy.

In numerous research and management programs, we have observed that even the most experienced koala spotter may only see 20–80% of koalas present at a site, especially if the vegetation is thick or the terrain difficult to move through.

Romane Cristescu with detection dog USC x IFAW detection dog Bear. Detection dogs have been trained to locate koala and their scats.
Detection Dogs for Conservation

Making the job even harder, existing koala habitat maps can be highly inaccurate and miss unexpected hotspots. However, computer modelling using the latest methods, if carefully validated on the ground, can produce more accurate maps.

Traditional surveys involve multiple people independently searching the same area, and correcting counts based on the number of koalas each observer sees. This helps account for the difficulties in koala counting, but it’s hard, slow and costly work.

Searching for koala scat (poo) also is a common method of determining koala habitat – wherever koalas spend time, they will leave scats. However, the small brown pellets are easily missed, and large surveys for scats are time consuming.

Detection dogs have been trained to locate koala scats: in one study, dogs were shown to be 150% more accurate and 20 times quicker than humans.

And because male koalas bellow during the breeding season, koalas can also be detected with acoustic surveys. Audio recorders are left at a survey sites and the recordings scanned for bellows to determine whether koalas are present.

Recently, heat-seeking drones have also been used to detect koalas. This method can be accurate and effective, especially in difficult terrain. We used them extensively to find surviving koalas after the 2019-20 bushfires.

Citizen scientists can also collect important data about koalas. Smartphone apps allow the community to report sightings around Australia, helping to build a picture of where koalas have been seen. However, these sightings are often limited to areas commonly traversed by people, such as in suburbia, near walking tracks and on private property.

Everyday citizens can help with koala counting.
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Getting the koala count right

All these methods involve a complex mix of strengths and weaknesses, which means the audit will need input from koala ecologists if it’s to be successful. Survey methods and sites must be chosen strategically to maximise the benefits of the funding.

Robust research data exists, but is patchy across the koala’s entire range. The first step could include collating all current data, including community sightings, to determine where additional surveys are needed. This will allow for funding to be prioritised to fill data gaps.

It is promising that the announcement includes monitoring over the long term. This will help identify population trends and better understand the response of koalas to ongoing threats. It will also reveal whether actions to address koala threats are working.

Finally, while threats to koalas are generally well understood, they can vary between populations. So the audit should allow for “threat mapping” – identifying threats and looking for ways to mitigate them.

Saving an iconic species

Last summer’s bushfires highlighted how koalas, and other native species, are vulnerable to climate change. And the clearing of koala habitat continues, at times illegally.

Government inquiries and reviews have shown state and federal environment laws are not preventing the decline of koalas and other wildlife. The federal laws are still under review.

However, the new funding underpins an important step – accurate mapping of koalas and their habitat for protection and restoration. This is a crucial task in protecting the future of this iconic Australian species.

The koala count is critical to protecting the species.
Shutterstock

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Romane H. Cristescu, Posdoc in Ecology, University of the Sunshine Coast; Celine Frere, Senior lecturer, University of the Sunshine Coast, and Desley Whisson, Senior Lecturer in Wildlife and Conservation Biology, School of Life and Environmental Sciences, Deakin University

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