Cartoon guide to biodiversity loss LXXIII

15 07 2022

Welcome to the fourth set of 6 cartoons for 2022. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.


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Cartoon guide to biodiversity loss LXXII

30 05 2022

Welcome to the third set of 6 cartoons for 2022. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.


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Can we resurrect the thylacine? Maybe, but it won’t help the global extinction crisis

9 03 2022

NFSA

(published first on The Conversation)

Last week, researchers at the University of Melbourne announced that thylacines or Tasmanian tigers, the Australian marsupial predators extinct since the 1930s, could one day be ushered back to life.

The thylacine (Thylacinus cynocephalus), also known as the ‘Tasmanian tiger’ (it was neither Tasmanian, because it was once common in mainland Australia, nor was it related to the tiger), went extinct in Tasmania in the 1930s from persecution by farmers and habitat loss. Art by Eleanor (Nellie) Pease, University of Queensland.
Centre of Excellence for Australian Biodiversity and Heritage

The main reason for the optimism was the receipt of a A$5 million philanthropic donation to the research team behind the endeavour.

Advances in mapping the genome of the thylacine and its living relative the numbat have made the prospect of re-animating the species seem real. As an ecologist, I would personally relish the opportunity to see a living specimen.

The announcement led to some overhyped headlines about the imminent resurrection of the species. But the idea of “de-extinction” faces a variety of technical, ethical and ecological challenges. Critics (like myself) argue it diverts attention and resources from the urgent and achievable task of preventing still-living species from becoming extinct.

The rebirth of the bucardo

The idea of de-extinction goes back at least to the the creation of the San Diego Frozen Zoo in the early 1970s. This project aimed to freeze blood, DNA, tissue, cells, eggs and sperm from exotic and endangered species in the hope of one day recreating them.

The notion gained broad public attention with the first of the Jurassic Park films in 1993. The famous cloning of Dolly the sheep reported in 1996 created a sense that the necessary know-how wasn’t too far off.

The next technological leap came in 2008, with the cloning of a dead mouse that had been frozen at –20℃ for 16 years. If frozen individuals could be cloned, re-animation of a whole species seemed possible.

After this achievement, de-extinction began to look like a potential way to tackle the modern global extinction crisis.

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The sixth mass extinction is happening now, and it doesn’t look good for us

2 03 2022

Mounting evidence is pointing to the world having entered a sixth mass extinction. If the current rate of extinction continues we could lose most species by 2200. The implication for human health and wellbeing is dire, but not inevitable.

In the timeline of fossil evidence going right back to the first inkling of any life on Earth — over 3.5 billion years ago — almost 99 percent of all species that have ever existed are now extinct. That means that as species evolve over time — a process known as ‘speciation’ — they replace other species that go extinct.

Extinctions and speciations do not happen at uniform rates through time; instead, they tend to occur in large pulses interspersed by long periods of relative stability. These extinction pulses are what scientists refer to as mass extinction events.

The Cambrian explosion was a burst of speciation some 540 million years ago. Since then, at least five mass extinction events have been identified in the fossil record (and probably scores of smaller ones). Arguably the most infamous of these was when a giant asteroid smashed into Earth about 66 million years ago in what is now the Gulf of Mexico. The collision vapourised species immediately within the blast zone. Later, species were killed off by climate change arising from pulverised particulates suspended in the atmosphere, as well as intense volcano activity stimulated by the buckling of the Earth’s crust from the asteroid’s impact. Together, about 76 percent of all species around at the time went extinct, of which the disappearance of the dinosaurs is most well-known. But dinosaurs didn’t disappear altogether — the survivors just evolved into birds.

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Fancy a pangolin infected with coronavirus? Apparently, many people do

30 12 2021

The logic of money contradicts the logic of species conservation and human health. As illegal trade has driven pangolins to near extinction, their hunting and market value has kept increasing ― even when we have known that they act as coronavirus reservoirs in the middle of the Covid-19 pandemic.

Sunda pangolin (Manis javanica) in a monsoon forest (Sumba Island, Indonesia). With adult weights up to 10 kg and body lengths around half a metre, these animals are mostly solitary and nocturnal, feed on ants and termites, and love tree climbing using bark hollows to shelter and give birth to singletons. The species occurs across mainland and islands of South East Asia, and became ‘Endangered’ in 2008 and ‘Critically Endangered’ in 2014, following a 80% decline in the last 20 years due to hunting and poaching. It has been the most heavily trafficked Asian species, and the IUCN’s assessment states: “… the incentives for harvesting and illegally trading in the species are universally high based on the high financial value of pangolin parts and derivatives”. Captive breeding is unlikely to deter wild collection because (among other reasons) farming costs are high (more so on a large scale) and, even if the species could be traded legally, wild versus farmed pangolin products and individuals are difficult to distinguish (23). Photo courtesy of Michael Pitts

Urbanites are attracted to exotic species, materials, and places. Our purchasing power seems to give us the right to buy any ‘object’ that we can pay for, no matter how exotic the object might be. In such a capitalist rationale, it is no surprise that > 150 thousand illegal cargos with wild animals and plants have been confiscated in 149 countries over the last two decades, moving some 6000 species from one place of the planet to another (1).

Social networks show people interacting with all kinds of fauna, creating the illusion that any animal can become a pet (2). And there’s a multi-$billion market of wildlife for a diverse array of uses including collecting, food, ornamentation, leisure, clothing and medicine (3-5). The paradox is that the rarer a species is, the higher its market value runs and the more lucrative selling it turns out to be, leading to more exploitation and rocketing extinction risk (6).

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And this little piggy went extinct

24 11 2021

Back in June of this year I wrote (whinged) about the disappointment of writing a lot of ecological models that were rarely used to assist real-world wildlife management. However, I did hint that another model I wrote had assistance one government agency with pig management on Kangaroo Island.

Well, now that report has been published online and I’m permitted to talk about it. I’m also very happy to report that, in the words of the Government of South Australia’s Department of Primary Industries and Regions (PIRSA),

Modelling by the Flinders University Global Ecology Laboratory shows the likelihood and feasibility of feral pig eradication under different funding and eradication scenarios. With enough funding, feral pigs could be eradicated from Kangaroo Island in 2 years.

This basically means that because of the model, PIRSA was successful in obtaining enough funding to pretty much ensure that the eradication of feral pigs from Kangaroo Island will be feasible!

Why is this important to get rid of feral pigs? They are a major pest on the Island, causing severe economic and environmental impacts both to farms and native ecosystems. On the agricultural side of things, they prey on newborn lambs, eat crops, and compete with livestock for pasture. Feral pigs damage natural habitats by up-rooting vegetation and fouling waterholes. They can also spread weeds and damage infrastructure, as well as act as hosts of parasites and diseases (e.g., leptospirosis, tuberculosis, foot-and-mouth disease) that pose serious threats to industry, wildlife, and even humans.

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Climate change will also make us more stupid

31 08 2021

Most people are at least vaguely aware that climate change isn’t good for us.

Let’s consider the obvious direct health effects, like heat exhaustion and stroke, dehydration, increased inhalation of particulate matter from bushfires and other pollutant sources, greater expression of allergies, higher incidence of cardiovascular and respiratory diseases, greater injury rates, and higher probability of disease transmission from flooding events (see review here).

Let’s not forget the rising incidence of mental illness either.

Then there are the climatic events that increase the probability of dying violently like in a bushfire or a flood, getting caned in a major storm by debris, personal injury from storm surges exacerbated by rising sea levels, or dying slowly due to undernutrition from crop failures.

Some of the more indirect, yet just-as-insidious repercussions are those climate-driven events that worsen all of the above, such as increasing poverty, rising violent interactions (both individual-level and full-on warfare), loss of healthcare capability (less infrastructure, fewer doctors), and increased likelihood of becoming a refugee.


So, when someone says increased warming at the pace we’re witnessing now isn’t a problem, tell them they’re full of shit.

But wait! There’s more!

Yes, climate change will also make us more stupid. Perhaps one of the lesser-appreciated byproducts of an increasingly warmer world driven by rising greenhouse-gas concentrations is the direct effects of carbon dioxide on a variety of physiological functions.

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It’s a tough time for young conservation scientists

24 08 2021

Sure, it’s a tough time for everyone, isn’t it? But it’s a lot worse for the already disadvantaged, and it’s only going to go downhill from here. I suppose that most people who read this blog can certainly think of myriad ways they are, in fact, still privileged and very fortunate (I know that I am).

Nonetheless, quite a few of us I suspect are rather ground down by the onslaught of bad news, some of which I’ve been responsible for perpetuating myself. Add lock downs, dwindling job security, and the prospect of dying tragically due to lung infection, many have become exasperated.

I once wrote that being a conservation scientist is a particularly depressing job, because in our case, knowledge is a source of despair. But as I’ve shifted my focus from ‘preventing disaster’ to trying to lessen the degree of future shittyness, I find it easier to get out of bed in the morning.

What can we do in addition to shifting our focus to making the future a little less shitty than it could otherwise be? I have a few tips that you might find useful:

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Pest plants and animals cost Australia around $25 billion a year — and it will get worse

2 08 2021
AAP

Corey J. A. Bradshaw, Flinders University and Andrew Hoskins, CSIRO

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


Shamefully, Australia has one of the highest extinction rates in the world.
And the number one threat to our species is invasive or “alien” plants and animals.

But invasive species don’t just cause extinctions and biodiversity loss – they also create a serious economic burden. Our research, published today, reveals invasive species have cost the Australian economy at least A$390 billion in the last 60 years alone.

Our paper – the most detailed assessment of its type ever published in this country – also reveals feral cats are the worst invasive species in terms of total costs, followed by rabbits and fire ants.

Without urgent action, Australia will continue to lose billions of dollars every year on invasive species.

Feral cats are Australia’s costliest invasive species. Source: Adobe Stock/240188862

Huge economic burden

Invasive species are those not native to a particular ecosystem. They are introduced either by accident or on purpose and become pests.

Some costs involve direct damage to agriculture, such as insects or fungi destroying fruit. Other examples include measures to control invasive species like feral cats and cane toads, such as paying field staff and buying fuel, ammunition, traps and poisons.

Our previous research put the global cost of invasive species at A$1.7 trillion. But this is most certainly a gross underestimate because so many data are missing.


Read more:
Attack of the alien invaders: pest plants and animals leave a frightening $1.7 trillion bill


As a wealthy nation, Australia has accumulated more reliable cost data than most other regions. These costs have increased exponentially over time – up to sixfold each decade since the 1970s.

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Attack of the alien invaders: pest plants and animals leave a frightening $1.7 trillion bill

19 04 2021

Shutterstock


They’re one of the most damaging environmental forces on Earth. They’ve colonised pretty much every place humans have set foot on the planet. Yet you might not even know they exist.

We’re talking about alien species. Not little green extraterrestrials, but invasive plants and animals not native to an ecosystem and which become pests. They might be plants from South America, starfish from Africa, insects from Europe or birds from Asia.

These species can threaten the health of plants and animals, including humans. And they cause huge economic harm. Our research, recently published in the journal Nature, puts a figure on that damage. We found that globally, invasive species cost US$1.3 trillion (A$1.7 trillion) in money lost or spent between 1970 and 2017.

The cost is increasing exponentially over time. And troublingly, most of the cost relates to the damage and losses invasive species cause. Meanwhile, far cheaper control and prevention measures are often ignored.

Yellow crazy ants attacking a gecko
Yellow crazy ants, such as these attacking a gecko, are among thousands of invasive species causing ecological and economic havoc. Dinakarr, CC0, Wikimedia Commons

An expansive toll

Invasive species have been invading foreign territories for centuries. They hail from habitats as diverse as tropical forests, dry savannas, temperate lakes and cold oceans.

They arrived because we brought them — as pets, ornamental plants or as stowaways on our holidays or via commercial trade.

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Worried about Earth’s future? Well, the outlook is worse than even scientists can grasp

14 01 2021

Daniel Mariuz/AAP

Corey J. A. Bradshaw, Flinders University; Daniel T. Blumstein, University of California, Los Angeles, and Paul Ehrlich, Stanford University

Anyone with even a passing interest in the global environment knows all is not well. But just how bad is the situation? Our new paper shows the outlook for life on Earth is more dire than is generally understood.

The research published today reviews more than 150 studies to produce a stark summary of the state of the natural world. We outline the likely future trends in biodiversity decline, mass extinction, climate disruption and planetary toxification. We clarify the gravity of the human predicament and provide a timely snapshot of the crises that must be addressed now.

The problems, all tied to human consumption and population growth, will almost certainly worsen over coming decades. The damage will be felt for centuries and threatens the survival of all species, including our own.

Our paper was authored by 17 leading scientists, including those from Flinders University, Stanford University and the University of California, Los Angeles. Our message might not be popular, and indeed is frightening. But scientists must be candid and accurate if humanity is to understand the enormity of the challenges we face.

Girl in breathing mask attached ot plant in container

Humanity must come to terms with the future we and future generations face. Shutterstock

Getting to grips with the problem

First, we reviewed the extent to which experts grasp the scale of the threats to the biosphere and its lifeforms, including humanity. Alarmingly, the research shows future environmental conditions will be far more dangerous than experts currently believe. Read the rest of this entry »





Time for a ‘cold shower’ about our ability to avoid a ghastly future

13 01 2021

I wish it need not have happened in my time,” said Frodo. “So do I,’ said Gandalf, “and so do all who live to see such times. But that is not for them to decide. All we have to decide is what to do with the time that is given us.”

Frodo Baggins and Gandalf, The Fellowship of the Ring

Today, 16 high-profile scientists and I published what I describe as a ‘cold shower’ about society’s capacity to avoid a ghastly future of warfare, disease, inequality, persecution, extinction, and suffering.

And it goes way beyond just the plight of biodiversity.

No one who knows me well would mistake me for an optimist, try as I might to use my colleagues’ and my research for good. Instead, I like to describe myself as a ‘realist’. However, this latest paper has made even my gloomier past outputs look downright hopeful.

And before being accused of sensationalism, let me make one thing abundantly clear — I sincerely hope that what we describe in this paper does not come to pass. Not even I am that masochistic.

I am also supportive of every attempt to make the world a better place, to sing about our successes, regroup effectively from our failures, and maintain hope in spite of evidence to the contrary.

But failing to acknowledge the magnitude and the gravity of the problems facing us is not just naïve, it is positively dangerous and potentially fatal.

It is this reason alone that prompted us to write our new paper “Underestimating the challenges of
avoiding a ghastly future
” just published in the new journal, Frontiers in Conservation Science.

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Grand Challenges in Global Biodiversity Threats

8 10 2020

Last week I mentioned that the new journal Frontiers in Conservation Science is now open for business. As promised, I wrote a short article outlining our vision for the Global Biodiversity Threats section of the journal. It’s open-access, of course, so I’m also copying here on ConservationBytes.com.


Most conservation research and its applications tend to happen most frequently at reasonably fine spatial and temporal scales — for example, mesocosm experiments, single-species population viability analyses, recovery plans, patch-level restoration approaches, site-specific biodiversity surveys, et cetera. Yet, at the other end of the scale spectrum, there have been many overviews of biodiversity loss and degradation, accompanied by the development of multinational policy recommendations to encourage more sustainable decision making at lower levels of sovereign governance (e.g., national, subnational).

Yet truly global research in conservation science is fact comparatively rare, as poignantly demonstrated by the debates surrounding the evidence for and measurement of planetary tipping points (Barnosky et al., 2012; Brook et al., 2013; Lenton, 2013). Apart from the planetary scale of human-driven disruption to Earth’s climate system (Lenton, 2011), both scientific evidence and policy levers tend to be applied most often at finer, more tractable research and administrative scales. But as the massive ecological footprint of humanity has grown exponentially over the last century (footprintnetwork.org), robust, truly global-scale evidence of our damage to the biosphere is now starting to emerge (Díaz et al., 2019). Consequently, our responses to these planet-wide phenomena must also become more global in scope.

Conservation scientists are adept at chronicling patterns and trends — from the thousands of vertebrate surveys indicating an average reduction of 68% in the numbers of individuals in populations since the 1970s (WWF, 2020), to global estimates of modern extinction rates (Ceballos and Ehrlich, 2002; Pimm et al., 2014; Ceballos et al., 2015; Ceballos et al., 2017), future models of co-extinction cascades (Strona and Bradshaw, 2018), the negative consequences of invasive species across the planet (Simberloff et al., 2013; Diagne et al., 2020), discussions surrounding the evidence for the collapse of insect populations (Goulson, 2019; Komonen et al., 2019; Sánchez-Bayo and Wyckhuys, 2019; Cardoso et al., 2020; Crossley et al., 2020), the threats to soil biodiversity (Orgiazzi et al., 2016), and the ubiquity of plastic pollution (Beaumont et al., 2019) and other toxic substances (Cribb, 2014), to name only some of the major themes in global conservation. 

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Never let a good crisis go to waste

11 05 2020

pandemic

First published in the Millennium Alliance for Humanity and the Biosphere Blog on 5 May 2020.

by Professor Dan Blumstein (University of California at Los Angeles), Professor Paul Ehrlich (Stanford University), and Corey Bradshaw (Flinders University)

Winston Churchill’s words have never been more important than today as we experience the society- and life-changing consequences of the COVID-19 pandemic.

The extent and severity of the disease is a result of ignoring decades of warnings by scientists about the general deterioration of humanity’s epidemiological environment, and specific warnings about confining live, wild animals in markets. The situation was made even more lethal by ignoring the warnings from epidemiologists and disease ecologists once it became clear that an imminent pandemic most likely arose from this practice. Many countries, including the United States, are still ignoring those warnings and the required actions to lessen the impact.

Accordingly, we should ask ourselves, “what else are we missing?” What other huge problems are hiding in plain sight where science could guide policy to avoid catastrophic future failures? For instance, there are two principal health threats that must be addressed immediately, and we must strike while the iron is hot.

The overuse of antibiotics in agriculture will cause widespread deaths from formerly treatable bacterial diseases because of the evolution of antibiotic resistance in microbes. The evolution of resistance is well-known, predictable, and obvious — not in retrospect, but now. By feeding antibiotics to otherwise healthy livestock, animals can be housed in higher densities and they grow faster. Read the rest of this entry »





Amphibian conservation in a managed world

1 04 2020

FrogBlog2

Crinia parinsignifera (top) and Limnodynastes tasmaniensis (bottom). Photo: Kate Mason

The amphibian class is diverse, and ranges from worm-like caecilians to tiny frogs that live their entire lives within bromeliads high in the rainforest canopy. Regardless of form or habit, all share the dubious honour of being cited as the world’s most endangered vertebrate taxon, and 41% of the species assessed are threatened with extinction. Rapidly changing climates will further exacerbate this situation as amphibians are expected to be more strongly affected than other vertebrates like birds or mammals.

This peril stems from a physiological dependence on freshwater.

Amphibians breathe (in part) through their skin, so they maintain moist skin surfaces. This sliminess means that most amphibians quickly dry out in dry conditions. Additionally, most amphibian eggs and larvae are fully aquatic. One of the greatest risks to populations are pools that dry too quickly for larval development, which leads to complete reproductive failure.

This need for freshwater all too often places them in direct competition with humans.

To keep pace with population growth, humans have engineered a landscape where the location, and persistence of water is tightly controlled. In seeking water availability for farming and amenity, we all too often remove essential habitats for amphibians and other freshwater fauna.

To protect amphibians from decline and extinction, land managers may need to apply innovative techniques to support vulnerable species. With amphibians’ strong dependence on freshwater, this support can be delivered by intelligently manipulating where and when freshwater appears in the landscape, with an eye to maintaining habitats for breeding, movement and refuge. A range of innovative approaches have been attempted to date, but they are typically developed in isolation and their existence is known only to a cloistered few. A collation of the approaches and their successes (and failures) has not occurred.

In our latest paper, we used a systematic review to classify water-manipulation techniques and to evaluate the support for these approaches. Read the rest of this entry »





Projecting global deaths from covid19

18 03 2020

covid

I know that it’s not the best way to project expected deaths from a pandemic disease, but being something of a demographer, I just couldn’t help myself.

I therefore took the liberty of punching in some basic probabilities into our world population model to see how many people could potentially die from covid19. But this is not an epidemiological model, so I’m probably vastly over-estimating the total death rates.

Nonetheless, the results were revealing.

I first took the expected mortality by age class based on the Chinese data so far. I then assumed a worst-case scenario of a 60% infection rate (i.e., 3 out of 5 of us will eventually catch the virus). I assumed these values across the entire globe (not taking into account greater or lesser susceptibility or probability of death among countries or regions).

I also considered two more scenarios: (i) double the mortality rate (in each age class), and (ii) the disease outbreak lasting two years instead of just one.

The graph below shows the four different outcomes based on these scenarios relative to the baseline (no covid): Read the rest of this entry »





Thirsty forests

1 02 2019

Climate change is one ingredient of a cocktail of factors driving the ongoing destruction of pristine forests on Earth. We here highlight the main physiological challenges trees must face to deal with increasing drought and heat.

Forests experiencing embolism after a hot drought. The upper-left pic shows Scots (Pinus sylvestris) and black (P. nigra) pines in Montaña de Salvador (Espuñola, Barcelona, Spain) during a hot Autumn in 2015 favouring a massive infestation by pine processionary caterpillars (Thaumetopoea pityocampa) and tree mortality the following year (Lluís Brotons/CSIC in InForest-CREAF-CTFC). To the right, an individual holm oak (Quercus ilex) bearing necrotic branches in Plasencia (Extremadura, Spain) during extreme climates from 2016 to 2017, impacting more than a third of the local oak forests (Alicia Forner/CSIC). The lower-left pic shows widespread die-off of trembling aspen (Populus tremuloides) from ‘Aspen Parkland’ (Saskatchewan, Canada) in 2004 following extreme climates in western North America from 2001 to 2002 (Mike Michaelian/Canadian Forest Service). To the right, several dead aspens near Mancos (Colorado, USA) where the same events hit forests up to one-century old (William Anderegg).

A common scene when we return from a long trip overseas is to find our indoor plants wilting if no one has watered them in our absence. But … what does a thirsty plant experience internally?

Like animals, plants have their own circulatory system and a kind of plant blood known as sap. Unlike the phloem (peripheral tissue underneath the bark of trunks and branches, and made up of arteries layered by live cells that transport sap laden with the products of photosynthesis, along with hormones and minerals — see videos here and here), the xylem is a network of conduits flanked by dead cells that transport water from the roots to the leaves through the core of the trunk of a tree (see animation here). They are like the pipes of a building within which small pressure differences make water move from a collective reservoir to every neighbours’ kitchen tap.

Water relations in tree physiology have been subject to a wealth of research in the last half a decade due to the ongoing die-off of trees in all continents in response to episodes of drought associated with temperature extremes, which are gradually becoming more frequent and lasting longer at a planetary scale (1). 

Embolised trees

During a hot drought, trees must cope with a sequence of two major physiological challenges (2, 3, 4). More heat and less internal water increase sap tension within the xylem and force trees to close their stomata (5). Stomata are small holes scattered over the green parts of a plant through which gas and water exchanges take place. Closing stomata means that a tree is able to reduce water losses by transpiration by two to three orders of magnitude. However, this happens at the expense of halting photosynthesis, because the main photosynthetic substrate, carbon dioxide (CO2), uses the same path as water vapour to enter and leave the tissues of a tree.

If drought and heat persist, sap tension reaches a threshold leading to cavitation or formation of air bubbles (6). Those bubbles block the conduits of the xylem such that a severe cavitation will ultimately cause overall hydraulic failure. Under those conditions, the sap does not flow, many parts of the tree dry out gradually, structural tissues loose turgor and functionality, and their cells end up dying. Thus, the aerial photographs showing a leafy blanket of forest canopies profusely coloured with greys and yellows are in fact capturing a Dantesque situation: trees in photosynthetic arrest suffering from embolism (the plant counterpart of a blood clot leading to brain, heart or pulmonary infarction), which affects the peripheral parts of the trees in the first place (forest dieback).

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Greater death rates for invasive rabbits from interacting diseases

30 05 2018

When it comes to death rates for invasive European rabbits (Oryctolagus cuniculus) in Australia, it appears that 1 + 1 = 2.1.

Pt tagged rab with RHD+myxo 1 10-08

Tagged European rabbit kitten infected with myxoma virus, but that died from rabbit haemorrhagic virus disease (RHDV). Photo by David Peacock, Biosecurity South Australia.

“Canberra, we have a problem” — Sure, it’s an old problem and much less of one than it used to be back in the 1950s, but invasive rabbits are nonetheless an ecological, conservation, and financial catastrophe across Australia.

relative rabbit abundance South Australia

Semi-schematic diagram, redrawn using data from Saunders and others and extended to include the recent spread of RHDV2, showing changes in rabbit abundance in relation to the introduction of biological control agents into north-eastern South Australia. Dotted lines indicate uncertainty due to lack of continuous annual data. The broken line indicates a level of about 0.5 rabbits ha-1, below which rabbits must be held to ensure recovery of native pastures and shrubs (from B. Cooke 2018 Vet Rec doi:10.1136/vr.k2105)

Rabbits used to reach plague numbers in much of agricultural and outback Australia, but the introduction and clever manipulation of two rather effective rabbit-specific viruses and insect vectors — first, myxoma virus in 1950, European rabbit fleas in the 1960s to help spread the virus, then Spanish rabbit fleas in the 1990s to increase spread into arid areas, and then rabbit haemorrhagic disease virus (RHDV) in 1995 — have been effective in dropping rabbit abundances by an estimated 75-80% in South Australia alone since the 1950s.

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Tiny, symbiotic organisms protect corals from predation and disease

20 12 2017

hydrozoan polyp

Hydrozoan polyps living on the surface of a coral (photo credit: S. Montano)

Corals could have some unexpected allies to cope with the multi-faceted threats posed by climate change.

In a new study published today in Proceedings of the Royal Society B, Montano and colleagues show how tiny hydrozoans smaller than 1 mm and commonly found in dense colonies on the surface of hard corals (see above photo) play an important ecological role.

Visually examining ~ 2500 coral colonies in both Maldivian and Saudi Arabian reefs, the scientists searched for signs of predation, temperature-induced stress, and disease. For each colony, they also recorded the presence of symbiotic hydrozoans. They demonstrated that corals living in association with hydrozoans are much less prone to be eaten by corallivorous (i.e., ‘coral-eating’) fish and gastropods than hydrozoan-free corals.

A likely explanation for this pattern could be the deterring action of hydrozoan nematocysts (cells capable of ejecting a venomous organelle, which are the same kinds found in jellyfish tentacles). An individual hydrozoan polyp of less than 1 mm clearly cannot cope with a corallivorous fish that is a billions of times larger, yet hydrozoans can grow at high densities on the surface of corals (sometimes > 50 individuals per cm2). This creates a sort of a continuous, ‘urticating‘ carpet that can discourage fish from foraging. Read the rest of this entry »





Who are the healthiest people in the world?

8 05 2017

healthyApologies for the little gap in my regular posts — I am in the fortunate position of having spent the last three weeks in the beautiful Villa Serbelloni in the village of Bellagio on the shores of Lake Como (northern Italy) engaged in writing a new book with my good friend and colleague, Professor Paul Ehrlich. Both of us received an invitation to become ‘Bellagio Centre Residents‘ by the Rockefeller Foundation to write the book in, shall we say, rather lush circumstances.

While I can’t yet give away all the juicy details of the book itself (we’ve only written about a third of it so far), I wanted to give you a little taste of some of the interesting results we’ve so far put together.

Today’s topic is on human health, which as I’ve written many times before, is in many ways linked to the quality of the environment in which people live. We are currently looking at which countries have the best human health statistics, as well as the best environmental conditions in which to live. Read the rest of this entry »








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