Many animals avoid contact with people. In protected areas of the African savanna, mammals flee more intensely upon hearing human conversations than when they hear lions or sounds associated with hunting. This fear of humans affects how species use and move in their habitat.
Throughout our lives, we interact with hundreds of wildlife species without stopping to think about it. These interactions can be direct, such as encountering wild animals while hiking in the mountains or driving through rural areas — or more deliberate, as when we engage with wildlife for food, sport, or trade. As hunters, fishers, and collectors, we kill more than 15,000 species of vertebrates — one-third of known diversity — a range of prey 300 times greater than that of any other predator our size (1).
Now, let’s look at it from the other side. Anyone who has survived an attack or a fatal accident, they understand that the experience is remembered for a lifetime. Likewise, animals store information about threatening or harmful encounters with humans (2). For them, adjusting their behaviour in response to human presence has implications for their survival and reproduction (3, 4), which are passed down from generation to generation (5). This ability to adapt, for example, determines which individuals, populations and species coexist with us in urbanised environments (6).
Response to dangerous sounds
Liana Zanette and her team measured the flight responses of wild mammals in the Greater Kruger National Park (South Africa) when exposed to sounds that signal danger (7) [video-summary]. To do this, Zanette recorded videos of more than 4,000 visits to 21 waterholes by 18 mammal species. During each visit, a speaker attached to a tree randomly played one of five playback sounds: hunting dogs barking, gunshots, lion growls, human conversations in a calm tone and, as a control, the songs of harmless birds.
Yes, it’s bad, especially for US-based scientists. It also affects scientists in Australia and the rest of the world. But there are ways to get around the problem. There might even be a silver lining to this dark cloud.
Trump cannot stop global climate action, although he might slow it. Nor can he hide the truth by restricting access to data. Climate research will continue despite Trump’s best efforts to hamstring scientists and research institutions.
No strength in ignorance
Last year was the warmest on record, a fact that yet again confirms our worst-case predictions. The world has already surpassed the (arbitrary) 1.5°C threshold increase relative to pre-industrial temperatures — a threshold that only a few years ago we didn’t think we would cross until 2030 at the earliest.
We’re now on track to be living in a world that’s 3°C hotter or more by the end of the century.
But ignoring climate change won’t make it go away. Like the Ministry of Truth in George Orwell’s classic dystopian novel, 1984, Trump seems to believe “ignorance is strength”. He’s trying to erase facts about the climate crisis, perhaps to keep people ignorant and subdued.
What this means for Australian climate science
Many Australian scientists (including me) collaborate regularly with US colleagues, share funding, and publish results together. Knowledge sharing and open-access data are the foundation of advances in science, so Trump’s assault will inevitably slow progress here.
For example, Australian and US scientists regularly collaborate in big-ticket research and policy development related to climate change, such as the Intergovernmental Panel on Climate Change’s Physical Science Basis reports. But even with fewer US scientists in the mix, the research and reporting will continue.
Other reputable climate-data repositories around the world include the European Union’s Climate Data Store, the University of East Anglia’s Climate Research Unit, the Netherlands Meteorological Institute’s Climate Explorer, and the independent WorldClim, to name a few.
While restricting access to US-based websites is inconvenient, we can readily get around the problem. Many of my colleagues have also been downloading data prior to the purge mandate to maintain access.
Consequences for the US
Over the past month I have been inundated with horror stories from many US-based colleagues in academia and the public service, who have lost their jobs and/or research funding. In addition to these very real personal tragedies, the bigger picture is even bleaker.
The loss of scientific and technical expertise these mass sackings entail weakens the capability of the US workforce to discover and develop solutions to climate change. Just when we need good scientific and engineering innovations more than ever, a massive capacity is being erased before our eyes.
More emissions mean more climate change, especially when you’re already one of the biggest contributors to the global problem. The US is the second-highest greenhouse emitter in the world, behind only China.
On his first day as president, Trump withdrew the US from the Paris climate agreement. This effectively removes his country from all binding limits on actions that contribute to climate change.
Weakening international treaties is a two-edged sword, because it not only lets the US off the leash, it also potentially discourages other nations from acting responsibly. Analogous to the “unresponsive bystander effect”, many nations may now be more hesitant to commit to reductions because one of the biggest emitters refuses to do anything about it.
Trump has also slashed US international aid, which will slow climate action in countries that need the most assistance.
Overall, faster rates of warming will inevitably put more strain on natural resources and agricultural production. This could increase the probability of international warfare over water, food and other essential natural resources. Because autocratic countries cope worse with food shortages than democratic ones, climate emergencies will penalise nations led by despots more heavily.
Trump’s foolhardy anti-climate campaign is enough to make many people despair. But there are a few faint glimmers of hope on the horizon.
As the US shirks its domestic and international responsibilities, other countries might resolve to do more. Not relying on the US could force capacity-building elsewhere. Some even suggest without the US at the table slowing progress, stronger climate action might result.
Americans have their own daunting fight on their hands. But the rest of the world will have to take up the slack if we have any chance of limiting the health, wealth, equality, human rights and biodiversity calamities now unfolding because of climate change.
Corey J. A. Bradshaw, Matthew Flinders Professor of Global Ecology and Node Leader in the ARC Centre of Excellence for Indigenous and Environmental Histories and Futures, Flinders University
The Black Summer bushfires of 2019–2020 that razed more than half of the landscape on Kangaroo Island in South Australia left an indelible mark on the island’s unique native biodiversity, which is still struggling to recover.
Flinders Chase National Park on Kangaroo Island after the 2019-2020 Black Summer fires (credit: CJA Bradshaw)
However, one big bonus for the environment’s recovery is the likely eradication of feral pigs (Sus scrofa). Invasive feral pigs cause a wide range of environmental, economic and social damages. In Australia, feral pigs occupy about 40% of the mainland and offshore islands, with a total, yet highly uncertain, population size estimated in the millions.
Feral pigs are recognised as a key threatening process under the Environment Protection and Biodiversity Conservation Act 1999, with impacts on at least 148 nationally threatened species and eight threatened ecological communities. They are a declared invasive species and the subject to control programs in all Australian jurisdictions.
Motion sensing cameras deployed during the eradication program capture feral pigs using their snouts to search for soil-borne food. This behaviour, called rooting, creates large areas of disturbed soil, killing native vegetation and spreading invasive weeds and pathogens (credit: PIRSA).
Human overpopulation is often depicted in the media in one of two ways: as either a catastrophic disaster or an overly-exaggerated concern. Yet the data understood by scientists and researchers is clear. So what is the actual state of our overshoot, and, despite our growing numbers, are we already seeing the signs that the sixth mass extinction is underway?
In a recent episode of The Great Simplification podcast, Nate Hagens was joined by global ecologist Corey Bradshaw to discuss his recent research on the rapid decline in biodiversity, how population and demographics will change in the coming decades, and what both of these will mean for complex global economies currently reliant on a stable environment.
Non-native species introduced mainly via increasing trade of goods and services have huge economic, health, and environmental costs. These ‘biological invasions’ involve the intentional or unintentional transport and release of species beyond their native biogeographical ranges, facilitating their potential spread.
However, there is limited information available demonstrating whether a country’s capacity to manage its invasive species is effective at limiting future damage.
Our new study published in the journal Ecological Economics found that while more affluent countries with higher economic activity are vulnerable to more damage from invasive species, they also have the highest potential to limit damages incurred by investing more in management. Consequently, a nation’s economic capability partially determines the efficacy of investing in the control and prevention of invasive species.
Australia is home to about one in 12 of the world’s species of animals, birds, plants and insects – between 600,000 and 700,000 species. More than 80% of Australian plants and mammals and just under 50% of our birds are found nowhere else.
But habitat destruction, climate change, and invasive species are wreaking havoc on Earth’s rich biodiversity, and Australia is no exception.
More and more species stand on the edge of oblivion. That’s just the ones we know enough about to list formally as threatened. Many more are in trouble, especially in the oceans. Change is the new constant. As the world heats up and ecosystems warp, new combinations of species can emerge without an evolutionary connection, creating novel communities.
It is still possible to stop species from dying out. But it will take an unprecedented effort.
The vulnerable southern bell (growling grass) frog (Litoria raniformis). Rupert Mathwin/Flinders University
A global database set up by scientists to assemble data on the economic cost of biological invasions in support of effective government management strategies has grown to include all known invasive species.
Now involving 145 researchers from 44 countries — the current version of InvaCost has 13,553 entries in 22 languages and enables scientists to develop a clear picture about the major threats globally of invasive species to ecosystems, biodiversity, and human well-being.
Biological invasions are caused by species introduced on purpose or accidentally by humans to areas outside of their natural ranges. From cats and weeds, to crop pests and diseases, invasive species are a worldwide scourge.
Invasive species have cost over US$2 trillion globally since the 1970s by damaging goods and services, and through the costs of managing them, and these economic costs are only increasing.
A new synthesis published in the journal BioSciencedocuments the progress of the InvaCost endeavour.The study provides a timeline of the state of invasion costs, starting with prior flaws and shortcomings in the scientific literature, then how InvaCost has helped to alleviate and address these issues, and what the future potentially holds for research and policymakers.
In light of new genetic research on the identity of ‘wild dogs’ and dingoes across Australia, the undersigned wish to express concern with current South Australia Government policy regarding the management and conservation of dingoes. Advanced DNA research on dingoes has demonstrated that dingo-dog hybridisation is much less common than thought, that most DNA tested dingoes had little domestic dog ancestry and that previous DNA testing incorrectly identified many dingoes as hybrids (Cairns et al. 2023). We have serious concerns about the threat current South Australian public policy poses to the survival of the ‘Big Desert’ dingo population found in Ngarkat Conservation Park and surrounding areas.
We urge the South Australian Government to:
Revoke the requirement that all landholders follow minimum baiting standards, including organic producers or those not experiencing stock predation. Specifically
Dingoes in Ngarkat Conservation park (Region 4) should not be destroyed or subjected to ground baiting and trapping every 3 months. The Ngarkat dingo population is a unique and isolated lineage of dingo that is threatened by inbreeding and low genetic diversity. Dingoes are a native species and all native species should be protected inside national parks and conservation areas.
Landholders should not be required to carry out ground baiting on land if there is no livestock predation occurring. Furthermore, landholders should be supported to adopt non-lethal tools and strategies to mitigate the risk of livestock predation including the use of livestock guardian animals, which are generally incompatible with ground and aerial 1080 baiting.
Revoke permission for aerial baiting of dingoes (incorrectly called “wild dogs”) in all Natural Resource Management regions – including within national parks. Native animals should be protected in national parks and conservation areas.
Cease the use of inappropriate and misleading language to label dingoes as “wild dogs”. Continued use of the term “wild dogs” is not culturally respectful to First Nations peoples and is not evidence-based.
Proactively engage with First Nations peoples regarding the management of culturally significant species like dingoes. For example, the Wotjobaluk nation should be included in consultation regarding the management of dingoes in Ngarkat Conservation Park.
Changes in South Australia public policy are justified based on genetic research by Cairns et al. (2023) that overturns previous misconceptions about the genetic status of dingoes. It demonstrates:
Most “wild dogs” DNA tested in arid and remote parts of Australia were dingoes with no evidence of dog ancestry. There is strong evidence that dingo-dog hybridisation is uncommon, with firstcross dingo-dog hybrids and feral dogs rarely being observed in the wild. In Ngarkat Conservation park none of DNA tested animals had evidence of domestic dog ancestry, all were ‘pure’ dingoes.
Previous DNA testing methods misidentified pure dingoes as being mixed. All previous genetic surveys of wild dingo populations used a limited 23-marker DNA test. This is the method currently used by NSW Department of Primary Industries, which DNA tests samples from NSW Local Land Services, National Parks and Wildlife Service, and other state government agencies. Comparisons of DNA testing methods find that the 23-marker DNA test frequently misidentified animals as dingo-dog hybrids. Existing knowledge of dingo ancestry across South Australia, particularly from Ngarkat Conservation park is incorrect; policy needs to be based on updated genetic surveys.
There are multiple dingo populations in Australia. High-density genomic data identified more than four wild dingo populations in Australia. In South Australia there are at least two dingo populations present: West and Big Desert. The West dingo population was observed in northern South Australia, but also extends south of the dingo fence. The Big Desert population extends from Ngarkat Conservation park in South Australia into the Big Desert and Wyperfield region of Victoria.
The Ngarkat Dingo population is threatened by low genetic variability. Preliminary evidence from high density genomic testing of dingoes in Ngarkat Conservation park and extending into western Victoria found evidence of limited genetic variability which is a serious conservation concern. Dingoes in Ngarkat and western Victoria had extremely low genetic variability and no evidence of gene flow with other dingo populations, demonstrating their effective isolation. This evidence suggests that the Ngarkat (and western Victorian) dingo population is threatened by inbreeding and genetic isolation. Continued culling of the Ngarkat dingo population will exacerbate the low genetic variability and threatens the persistence of this population.
Have you ever watched a nature documentary and marvelled at the intricate dance of life unfolding on screen? From the smallest insect to the largest predator, every creature plays a role in the grand performance of our planet’s biosphere. But what happens when one of these performers disappears?
In this post, we delve into our recent article Estimating co-extinction risks in terrestrial ecosystems just published in Global Change Biology, in which we discuss the cascading effects of species loss and the risks of ‘co-extinction’.
But what does ‘co-extinction’ really mean?
Imagine an ecosystem as a giant web of interconnected species. Each thread represents a relationship between two species — for example, a bird that eats a certain type of insect, or a plant that relies on a specific species of bee for pollination. Now, what happens if one of these species in the pair disappears? The thread breaks and the remaining species loses an interaction. This could potentially lead to its co-extinction, which is essentially the domino effect of multiple species losses in an ecosystem.
A famous example of this effect can be seen with the invasion of the cane toad (Rhinella marina) across mainland Australia, which have caused trophic cascades and species compositional changes in these communities.
The direct extinction of one species, caused by effects such as global warming for example, has the potential to cause other species also to become extinct indirectly.
The way that eels migrate along rivers and seas is mesmerising. There has been scientific agreement since the turn of the 20th Century that the Sargasso Sea is the breeding home to the sole European species. But it has taken more than two centuries since Carl Linnaeus gave this snake-shaped fish its scientific name before an adult was discovered in the area where they mate and spawn.
Even among nomadic people, the average human walks no more than a few dozen kilometres in a single trip. In comparison, the animal kingdom is rife with migratory species that traverse continents, oceans, and even the entire planet (1).
The European eel (Anguilla anguilla) is an outstanding example. Adults migrate up to 5000 km from the rivers and coastal wetlands of Europe and northern Africa to reproduce, lay their eggs, and die in the Sargasso Sea — an algae-covered sea delimited by oceanic currents in the North Atlantic.
The European eel (Anguilla Anguilla) is an omnivorous fish that migrates from European and North African rivers to the Sargasso Sea to mate and die (18). Each individual experiences 4 distinct developmental phases, which look so different that they have been described as three distinct species (19): A planktonic, leaf-like larva (ilecocephalus phase) emerges from each egg and takes up to 3 years to cross the Atlantic. Off the Afro-European coasts, the larva transforms into a semi-transparent tiny eel (iiglass phase) that enters wetlands and estuaries, and travels up the rivers as it gains weight and pigment (iiiyellow phase). They remain there for up to 20 years, rarely growing larger than 1 m in length and 4 kg in weight (females are larger than males) — see underwater footage here and here. Sexual maturity ultimately begins to adjust to the migration to the sea: a darker, saltier, and deeper environment than the river. Their back and belly turn bronze and silver (ivsilver phase), respectively, the eyes increase in size and the number of photoreceptors multiplies (function = submarine vision), the stomach shrinks and loses its digestive function, the walls of the swim bladder thicken (function = floating in the water column), and the fat content of tissues increases by up to 30% of body weight (function = fuel for transoceanic travelling). And finally, the reproductive system will gradually develop while eels navigate to the Sargasso Sea — a trip during which they fast. Photos courtesy of Sune Riis Sørensen (2-day embryo raised at www.eel-hatch.dk and leptocephalus from the Sargasso Sea) and Lluís Zamora (Ter River, Girona, Spain: glass eels in Torroella de Montgrí, 70 cm yellow female in Bonmatí, and 40 cm silver male showing eye enlargement in Bescanó). Eggs and sperm are only known from in vitro fertilisation in laboratories and fish farms (20).
As larvae emerge, they drift with the prevailing marine currents over the Atlantic to the European and African coasts (2). The location of the breeding area was unveiled in the early 20th Century as a result of the observation that the size of the larvae caught in research surveys gradually decreased from Afro-European land towards the Sargasso Sea (3, 4). Adult eels had been tracked by telemetry in their migration route converging on the Azores Archipelago (5), but none had been recorded beyond until recently.
Crossing the Atlantic
To complete this piece of the puzzle, Rosalind Wright and collaborators placed transmitters in 21 silver females and released them in the Azores (6). These individuals travelled between 300 and 2300 km, averaging 7 km each day. Five arrived in the Sargasso Sea, and one of them, after a swim of 243 days (from November 2019 to July 2020), reached what for many years had been the hypothetical core of the breeding area (3, 4). It is the first direct record of a European eel ending its reproductive journey.
Eels use the magnetic fields in their way back to the Sargasso Sea and rely on an internal compass that records the route they made as larvae (7). The speed of navigation recorded by Wright is slower than in many long-distance migratory vertebrates like birds, yet it is consistent across the 16 known eel species (8).
Telemetry (6) and fisheries (14) of European eel (Anguilla anguilla). Eel silhouettes indicate the release point of 21 silver females in Azores in 2018 (orange) and 2019 (yellow), the circles show the position where their transmitters stopped sending signals, and the grey background darkens with water depth. The diagrams display the distance travelled and the speed per eel, where the circle with bold border represents the female that reached the centre of the hypothetical spawning area in the Sargasso Sea (dashed lines in the map) (3). Blue, green and pink symbols indicate the final location of eels equipped with teletransmitters in previous studies, finding no individual giving location signals beyond the Azores Archipelago (6). The barplot shows commercial catches (1978-2021) of yellow+silver eels in those European countries with historical landings exceeding 30,000 t (no data available for France prior to 1986), plus Spain (6120 t from 1951) — excluding recreational fishery and farming which, in 2020, totalled 300 and 4600 t, respectively (14). Red circles represent glass-eel catches added up for France (> 90% of all-country landings), Great Britain, Portugal, and Spain. Catches have kept declining since the 1980s. One kg of glass eels contains some 3000 individuals, so the glass-eel fishery has a far greater impact on stocks than the adult fishery.
Wright claimed that, instead of swiftly migrating for early spawning, eels engage in a protracted migration at depth. This behaviour serves to conserve their energy and minimises the risk of dying (6). The delay also allows them to reach full reproductive potential since, during migration, eels stop eating and mobilise all their resources to swim and reproduce (9).
Other studies have revealed that adults move in deep waters in daylight but in shallow waters at night, and that some individuals are faster than others (3 to 47 km per day) (5). Considering that (i) this fish departs Europe and Africa between August and December and (ii) spawning occurs in the Sargasso Sea from December to May, it is unknown whether different individuals might breed 1 or 2 years after they begin their oceanic migration.
Management as complex as life itself
The European eel started showing the first signs of decline at the end of the 19th Century (10, 11). In 2008, the species was listed as Critically Endangered by the IUCN, and its conservation status has since remained in that category — worse than that of the giant panda (Ailuropoda melanoleuca) or the Iberian lynx (Lynx pardinus).
Flooding in the Murray-Darling Basin is creating ideal breeding conditions for many native species that have evolved to take advantage of temporary flood conditions. Led by PhD candidate Rupert Mathwin, our team developed virtual models of the Murray River to reveal a crucial link between natural flooding and the extinction risk of endangered southern bell frogs (Litoria raniformis; also known as growling grass frogs).
Southern bell frogs are one of Australia’s 100 Priority Threatened Species. This endangered frog breeds during spring and summer when water levels increase in their wetlands. However, the natural flooding patterns in Australia’s largest river system have been negatively impacted by expansive river regulation that some years, sees up to 60% of river water extracted for human use.
Our latest paper describes how we built computer simulations of Murray-Darling Basin wetlands filled with simulated southern bell frogs. By changing the simulation from natural to regulated conditions, we showed that modern conditions dramatically increase the extinction risk of these beloved frogs.
The data clearly indicate that successive dry years raise the probability of local extinction, and these effects are strongest in smaller wetlands. Larger wetlands and those with more frequent inundation are less prone to these effects, although they are not immune to them entirely. The models present a warning — we have greatly modified the way the river behaves, and the modern river cannot support the long-term survival of southern bell frogs.’
Following my annual tradition, I present the retrospective list of the ‘top’ 20 influential papers of 2022 as assessed by experts in Faculty Opinions(formerly known as F1000). These are in no particular order. See previous years’ lists here: 2021, 2020, 2019, 2018, 2017, 2016, 2015, 2014, and 2013.
Climate change is one of the main drivers of species loss globally. We know more plants and animals will die as heatwaves, bushfires, droughts and other natural disasters worsen.
But to date, science has vastly underestimated the true toll climate change and habitat destruction will have on biodiversity. That’s because it has largely neglected to consider the extent of “co-extinctions”: when species go extinct because other species on which they depend die out.
Our new research shows 10% of land animals could disappear from particular geographic areas by 2050, and almost 30% by 2100. This is more than double previous predictions. It means children born today who live to their 70s will witness literally thousands of animals disappear in their lifetime, from lizards and frogs to iconic mammals such as elephants and koalas.
But if we manage to dramatically reduce carbon emissions globally, we could save thousands of species from local extinction this century alone.
Ravages of drought will only worsen in coming decades. CJA Bradshaw
An extinction crisis unfolding
Every species depends on others in some way. So when a species dies out, the repercussions can ripple through an ecosystem.
For example, consider what happens when a species goes extinct due to a disturbance such as habitat loss. This is known as a “primary” extinction. It can then mean a predator loses its prey, a parasite loses its host or a flowering plant loses its pollinators.
A real-life example of a co-extinction that could occur soon is the potential loss of the critically endangered mountain pygmy possum (Burramys parvus) in Australia. Drought, habitat loss, and other pressures have caused the rapid decline of its primary prey, the bogong moth (Agrotis infusa).
The conservation, environment, and sustainability literature is rife with the term ‘collapse’, applied to concepts as diverse as species extinction to the complete breakdown of civilisation. I have also struggled with its various meanings and implications, so I’m going to attempt to provide some clarity on collapse for my own and hopefully some others’ benefit.
From a strictly ecological perspective, ‘collapse’ could be described in the following (paraphrased) ways:
abrupt transition of one ecosystem state to another, usually invoking the idea that something has declined in the process (species richness, beta diversity, functional diversity, trophic network connectance, trait volume, production, etc.);
But there is still nor formal definition of ‘collapse’ in ecology, as identified by several researchers (Keith et al. 2013; Boitani et al. 2015; Keith et al. 2015; Sato and Lindenmayer 2017; Bland et al. 2018). While this oversight has been discussed extensively with respect to quantifying changes, I can find nothing in the literature that attempts a generalisable definition of what collapse should mean. Perhaps this is because it is not possible to identify a definition that is sufficiently generalisable, something that Boitani et al. (2015) described with this statement:
“The definition of collapse is so vague that in practice it will be possible (and often necessary) to define collapse separately for each ecosystem, using a variety of attributes and threshold values
Despite all the work that has occurred since then, I fear we haven’t moved much beyond that conclusion.
Hell, cutting down the trees in the bush block next to my property constitutes a wholesale ‘collapse’ of the microcommunity of species using that patch of bush. An asteroid hitting the Earth and causing a mass extinction is also collapse. And everything in-between.
But at least ecologists have made some attempts to define and quantify collapse, even if an acceptable definition has not been forthcoming. The sustainability and broader environment literature has not even done that.
This week I’m going to discuss national indices of economic performance and prosperity. There are indeed some surprises.
But standard metrics of economic performance at the national level almost universally fail to encapsulate the sustainable economic prosperity of its citizens. One could, for example, simply list the ‘wealthiest’ nations according to simple economic turnover by employing the standard, but wholly unsatisfactory metrics of gross domestic product (GDP) and gross national income (GNI). Even most economists admit that GDP and GNI are dreadful measures of ‘wealth’, and the differences between them are largely immaterial.
Top 5 ‘wealthiest’ nations according to per-capita gross national income: Qatar, Macao, Singapore, Kuwait, Luxembourg.
It is probably easier to view GDP as a speedometer, for it measures the speed with which an economy is contributing to the generation of goods and services (i.e., economic turnover), but it does not measure the loss of biodiversity, ecosystem services, and other environmental assets such as forests and mined resources, it does not measure the build-up of greenhouse gases or hormone-mimicking toxic chemicals, nor does it take depreciation of physical capital in our society’s infrastructure in account. As it turns out, GDP actually rises following environmental disasters such as a major oil spill because of the jobs created to clean up the mess, but it does not measure in any way the economic advantage of growing produce in your garden because the goods are not ‘traded’ in the standard market.
Nor does GDP account for the disparity in wealth among a nation’s citizens, so even though most people might be poor, the existence of even a handful of billionaires can in fact raise a country’s GDP. The GDP metric is so unappealing that even the World Bank has tried to come up with better ways to measure wealth. Although it still falls short of measuring true wealth, ‘total wealth’ — measured as the present (discounted) value of future consumption that is ‘sustainable’ — tries to take into account a country’s present wealth minus damage to its non-renewable stock that is currently being exploited unsustainably (e.g., forests). As such, economic policies based on total wealth would be better able to ensure the long-term sustainability of a nation by including the ‘stock’ of existing capital that includes natural capital.
Top 5 ‘wealthiest’ nations according to per-capita total wealth: Norway, Qatar, Switzerland, Luxembourg, Kuwait.
Nearly a decade ago (my how time flies*), I wrote a post about the guaranteed failure of government policies purporting no-extinction targets within their environmental plans. I was referring to the State of South Australia’s (then) official policy of no future extinctions.
In summary, zero- (or no-) extinction targets at best demonstrate a deep naïvety of how ecology works, and at worst, waste a lot of resources on interventions doomed to fail.
4. Climate change will also guarantee additional (perhaps even most) future extinctions irrespective of Australian policies.
I argued that no-extinction policies are therefore disingenuous to the public in the extreme because they sets false expectations, engender disillusionment after inevitable failure, and ignores the concept of triage — putting our environment-restoration resources toward the species/systems with the best chance of surviving (uniqueness notwithstanding).
Now that the Australian election has been called for next month, here are a few cartoon reminders of the state of environmental politics in this country (hint: they’re abysmal). I’ve surpassed my normal 6 cartoons/post here in this second set for 2022 because, well, our lives depend on the outcome of 21 May. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.
Carnivores are essential components of trophic webs, and ecosystem functions crumble with their loss. Novel data show the connection between calcareous reefs and sea otters under climate change.
Trophic cascade on the Aleutian Islands (Alaska, USA) linking sea otters (Enhydra lutris) with sea urchins (Strongylocentrotus polyacanthus) and calcareous reefs (Clathromorphum nereostratum). With males weighting up to 50 kg, sea otters have been IUCN-catalogued as Endangered since 2000. The top photo shows a male in a typical, belly-up floating position. The bottom photo shows live (pinkish) and dead (whitish) tissue on the reef surface as a result of grazing of sea urchins at a depth of 10 m. Sea otters are mesopredators, typically foraging on small prey like sea urchins, but their historical decline due to overhunting unleashed the proliferation of the echinoderms. At the same time, acidification and sea-water warming have softened the skeleton of the reefs, allowing for deeper grazing by sea urchins that eliminate the growth layer of living tissue that give the reefs their pinkish hue. Large extents of dead reefs stop fixing the excess in carbonic acid, whose carbon atoms sea water sequesters from the atmosphere enriched in carbon by our burning of fossil fuels. Photos courtesy of Joe Tomoleoni taken in Moss Landing – California, USA (otter), and on the Near Islands – Aleutian Archipelago, Alaska (reef).
For most, the decisions made by people we have never met affect our daily lives. Other species experience the same phenomenon because they are linked to one another through a trophic cascade.
A trophic cascade occurs when a predator limits the abundance or behaviour of its prey, in turn affecting the survival of a third species in lower trophic levels that have nothing directly to do with the predator in question (1).
Sea otters (Enhydra lutris) represent a text-book example of a trophic cascade. These mustelids (see video footage here and here) hunt and control the populations of sea urchins (Strongylocentrotus polyacanthus), hence favouring kelp forests — the fronds of which are eaten by the sea urchins.
Removing the predator from the equation should lead to more sea urchins and less kelp, and this chain of events is exactly what happened along the coasts of the North Pacific (2, 3). The historical distribution of sea otters once ranged from Japan to Baja California through the Aleutian Islands (see NASA’s photo from space, and documentary on the island of Unimak), a sub-Arctic, arc-shaped archipelago including > 300 islands between Alaska (USA) and the Kamchatka Peninsula (Russia), extending ~ 2000 kilometres, and having a land area of ~ 18,000 km2.
But the fur trade during the 18th and 19th centuries brought the species to the brink of extinction, down to < 2000 surviving individuals (4). Without otters, sea urchins boomed and deforested kelp ecosystems during the 20th Century (5). Now we also know that this trophic cascade has climate-related implications in other parts of the marine ecosystem.
Underwater bites
Doug Rasher and collaborators have studied the phenomenon on the Aleutian Islands (6). The seabed of this archipelago is a mix of sandy beds, kelp forests, and calcareous reefs made up of calcium and magnesium carbonates fixed by the red algae Clathromorphum nereostratum. These reefs have grown at a rate of 3 cm annually for centuries as the fine film of living tissue covering the reef takes the carbonates from the seawater (7).
On the whole, I am inclined to conclude that my experience of academia and publishing my work has been largely benign. Despite having published 120-odd peer-reviewed papers, I can count the number of major disputes on one hand. Where there have been disagreements, they have centred on issues of content, and despite the odd grumble, things have rarely escalated to the ad hominem. I have certainly never experienced concerted attacks on my work.
But that changed recently. I work in water science, participating in and leading multi-disciplinary teams that do research directly relevant to water policy and management. My colleagues and I work closely with state and federal governments and are often funded by them through a variety of mechanisms. Our teams are a complex blend of scientists from universities, state and federal research agencies, and private-sector consultancies. Water is big business in Australia, and its management is particularly pertinent as the world’s driest inhabited continent struggles to come to terms with the impacts of climate change.
In the last 10 years, Australia has undergone a AU$16 billion program of water reform that has highlighted the extreme pressure on ecosystems, rural communities, and water-dependent industries. In 2019, two documentaries (Cash Splash and Pumped) broadcast by the Australian Broadcasting Corporation were highly critical of the outcomes of water reform. A group of scientists involved in working on the Murray-Darling Basin were concerned enough about the accuracy of aspects of those stories to support Professor Rob Vertessy from the University of Melbourne in drafting an Open Letter in response. I was a co-author on that letter, and something into which I did not enter lightly. We were very concerned about being seen to advocate for any particular policy position, but were simultaneously committed to contributing to an informed public debate. A later investigation by the Australian Communications and Media Authority also highlighted concerns with the Cash Splash documentary.
Fast forward to 2021 and the publication of a paper by Colloff et al. (2021) in the Australasian Journal of Water Resources. In that paper, the authors were critical of the scientists that had contributed to the Open Letter and claimed they had been subject to “administrative capture” and “issue advocacy”. Administrative capture is defined here as:
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.
Many animals avoid contact with people. In protected areas of the African savanna, mammals flee more intensely upon hearing human conversations than when they hear lions or sounds associated with hunting. This fear of humans affects how species use and move in their habitat. Throughout our lives, we interact with hundreds of wildlife species without…
Deep-sea sharks include some of the longest-lived vertebrates known. The record holder is the Greenland shark, with a recently estimated maximum age of nearly 400 years. Their slow life cycle makes them vulnerable to fisheries. Humans rarely live longer than 100 years. But many other animals and plants can live for several centuries or even millennia, particularly…
Procreating with a relative is taboo in most human societies for many reasons, but they all stem from avoiding one thing in particular — inbreeding increases the risk of genetic disorders that can seriously compromise a child’s health, life prospects, and survival. While we all inherit potentially harmful mutations from our parents, the effects of…
ConservationBytes.com 