Using animals as sport symbols reflects the integration of biodiversity into cultural identity and the transmission of collective values. This raises the possibility that the economic muscle of the sport industry could translate its symbolic capital into tangible commitments to biodiversity conservation.
Those who have had the privilege of travelling in remote areas might have come across an unexpected scene: a football pitch in the middle of the Amazon rain forest or on the slopes of the Andes, a basketball court on the side of a Buddhist temple, or an ice hockey rink on a snow-ploughed lake in remote northern Canada.
Sport is a global industry that generates identity, belonging, education, and shared emotions for both athletes and their avid spectators (1). Sporting affinities now rival the sense of nationhood once shared by citizens during warfare (2).
Now in our heavily monetised world, sport clubs rely on their fans through tickets and merchandising, and indirectly through television rights and advertising. In this both emotional and commercial relationship, expressions such as being true to the badge reflect the central role of corporate symbols in building bonds between a club and its supporters (3).
Sport club logos with animal iconography. Top row: examples of the grey wolf (Canis lupus) in Neftekhimik Nizhnekamsk (ice hockey, Russia), Warrington Wolves (rugby, England), Wolverhampton Wanderers (football, England), and Roma (football, Italy). Second row: bald eagle (Haliaeetus leucocephalus) in Essex Eagles (cricket, England), Adler Mannheim (handball, Germany), and Philadelphia Eagles (American football, USA). Third row: Free State Cheetahs (represented by the cheetah Acinonyx jubatus; rugby, South Africa), Toronto Blue Jays (blue jay Cyanocitta cristata; baseball, Canada), Memphis Grizzlies (grizzly bear Ursus arctos horribilis; basketball, USA) and Hisamitsu Springs (Japanese white-eye Zosterops japonicas; volleyball, Japan). Fourth row: six Spanish football clubs. Clubs featuring wolves and eagles are often associated with the symbolic qualities of these species (e.g., intelligence, prowess, fealty, bravery, strength). In football, animals reflect represent the history and heraldry of cities and regions, as seen in the crests of in Atlético de Madrid (brown bear Ursus arctos), AS Roma and Athletic Club (wolf), Cultural Deportiva Leonesa and Atlético Osasuna (lion Panthera leo), CD Castellón (raptor) and Levante UD (bat). Photos: Gary Kramer (wolf) and Andy Morffew (eagle).
In professional sport such as football, clubs increasingly function as brands (4) where even traditional logos are modified to enhance a team’s commercial value and strengthen audience loyalty (5). In this process, biodiversity becomes relevant because the iconography of many sport organisations incorporates representations of plants and animals.
Sport fauna
To quantify this phenomenon, Ugo Arbieu and collaborators analysed the presence of animals in club names, crests, and fan nicknames among 10 professional team sports across 50 countries (6). They found that 727 teams use 161 different animal species in their corporate imagery. Football and basketball lead in the number of species represented due to the large number of clubs worldwide, but American football, rugby and baseball display greater symbolic fauna diversity per club. Mammals and birds are the most common, particularly carnivores and raptors.
Animal symbols in club iconography (names, logos, fan nicknames) for the sports with the largest audiences (6): basketball, handball, baseball, cricket, football, American football, ice hockey and volleyball. The sample excludes 106 teams that use domesticated species as identity symbols, includes 163 men’s leagues and 67 women’s leagues, respectively, and the animal species depicted in the emblems of 48 teams could be identified. Horizontal bars above show the most represented animal groups (top panel), and the 15 species most frequently featured (middle panel). Bottom panel: percentage of symbols according to the IUCN’s conservation status of the species, where ‘threatened’ includes the categories Near Threatened, Endangered and Extinct. The trend indicates that sport clubs prefer to identify themselves with large mammal species that are threatened.
This pattern is not coincidental, for it reflects the historical bias of science and conservation towards large, charismatic vertebrates (7), but also the uneven availability of biological information and our social preferences for certain species (8). These preferences are even reflected in the animal emojis we share regularly on social media (9).
Arbieu’s study also revealed that clubs tend to favour images of threatened fauna (6), possibly due to their higher symbolic impact and media visibility (10). Moreover, although clubs in Europe and the Americas more often depict exotic animals, native species dominate in Africa, Asia, and Oceania (6). This suggests that the choice of an animal as an emblem is the product of not only aesthetic or symbolic criteria, but also of cultural roots and the historical relationship of societies with their local fauna.
Under the sea where there is little or no light, the foraging, communication, and orientation of whales and many other marine animals depend on sound. But increasing human activity has transformed the soundscape of seas and oceans. This change affects the behaviour of species and presents challenges in managing a problem of global scale.
Many like me feel uneasy when we hear a siren on the street. An ambulance, fire fighters, or the police can remind us of times when we or someone close to us suffered a heart attack, a fire, or a robbery. Animals can also associate sounds with risky situations they have experienced before, such as an attack from a predator, in their own lives or in the evolutionary history of their species.
For example, many types of whales are prey to killer whales (1) [watch predatory scenes here, here, here], and not only do they recognise the presence of their main predator by sound, but the vocalisations of some species have evolved to fall outside the killer whale’s hearing range (2). When faced with such a threatening sound, species must decide whether the risk of being hunted is great enough to justify interrupting essential activities such as feeding or mating (3). Interestingly, there are alarm signals that are so general in the animal kingdom, like a simple noise, that prey animals might react to them by spending time and energy to protect themselves, even when there is no real threat (4).
Tagging cetaceans off the Canary Islands to study their behaviour in relation to human and environmental disturbance. Above, 2 short-finned pilot whales (Globicephala macrorhynchus) in the southwest Tenerife, and below 2 Blainville’s beaked whales (Mesoplodon densirostris) in the Mar de las Calmas southwest of El Hierro. The back-mounted devices are DTAGs [read here, here and here]: they are attached by suction cups on top of which an encased electronic device records time series of environmental (depth, pressure, temperature, magnetic fields) and biological (e.g., swimming speed, heart rate, echolocation) variables. Watch videos of scientists deploying DTAGs on a range of cetacean species using a long stick here and here and drones here and here. Photos courtesy of O Marín Delgado (pilot whales) and C Yzoard (beaked whales); projects based at Universidad de La Laguna, Tenerife, Spain and led by N Aguilar de Soto [see stories here and here] (9, 26-29).
Naval sonar and killer whales
To examine this issue, Patrick Miller and his colleagues used underwater microphones to play recordings of killer whale sounds and ship sonar in the presence of 43 individuals from four cetacean species off the coasts of Norway and its Svalbard Archipelago (5): northern bottlenose whale (Hyperoodon ampullatus), humpback whale (Megaptera novaeangliae), long-finned pilot whale (Globicephala melas), and sperm whale (Physeter macrocephalus) [see press release for this research paper, listen to a podcast discussing findings]. During the experiment, each of the 43 individuals studied was fitted with a digital device attached to the skin using a suction cup. These devices recorded the animals’ movements and vocalisations. In total, the researchers collected 179 hours of baseline behaviour data in natural background noise, along with 7 hours of behavioural data in response to experimental playbacks of sonar [listen] and killer whale [listen] sounds.
Those of us living with cats share our homes with an ancestral predator, one adapted for hunting and the frequent, exclusive consumption of meat. These instincts become fully activated outside the domestic environment, where cats pose a global threat to wildlife.
Pets are family. We celebrate their arrival with the same joy as a grand homecoming, and their absence leaves a grief as deep as losing a loved one. In bonding with cats and dogs, we often attribute human abilities and emotions to them.
But beyond this affection, domestic animals still carry the instincts and genetic legacy of their wild ancestors(1, 2). My cats — Caruso, Muesli, and Plata — have been calm and loving, but they have always enjoyed a real hunt (3). When a moth comes in through a window, they seem possessed: their mouths chitter and make clicking sounds, they leap from one piece of furniture to another, and their heads snap sharply between the insect’s position and other points in the room, calculating the best spot from which to pounce on their prey. That is why when they become feral, cats and dogs integrate into food chains like any other species: they compete for ecosystem resources, hunt and are hunted, and hybridise and exchange diseases with other carnivores (4, 5).
Top: cat eating an Eurasian blue tit (Cyanistes caeruleus), a common visitor to home gardens in Nijmegen (Netherlands). Bottom, domestic cat after hunting an Eastern cottontail rabbit (Sylvilagus floridanus) in a residential neighbourhood of Stratford (Connecticut, USA). Photos courtesy of Jelger Herder (Nijmegen) and Scott Kruitbosch (Stratford). Scott is a photographer and conservationist. Near sunset on 30/09/2020, while intently observing local wildlife, he witnessed a neighbourhood cat sneak up from behind on a cottontail feeding in open grass and grab it. For years, Scott has had extremely negative interactions, both in person and online, with local residents over these issues. These exchanges have revealed that many people show little concern for wildlife or for the dangers their outdoor cats face, and believe that their cats would not, or could not, harm wildlife.
Domestic cats are highly skilled hunters, and their predatory interactions with a wide range of prey are widely documented in social media and documentaries. Some examples include cats catching: bats and birds on the wing, butterflies, chipmunks, dragons, fishes, grasshoppers, frogs, lizards, mice, owls, rabbits, seagulls, snakes, squirrels, and wallabies. See an award-winning photo depicting wildlife with fatal injuries caused by cats recorded in 2019 at a single animal hospital in the USA, and a video showing domestic cats mimicking bird calls and some cat owners explaining that their pets reject commercial cat food after experiencing the thrill of hunting real prey. The documentary Secret Life of Cats contextualises the ecological challenges posed by free-roaming cats.
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.
Using animals as sport symbols reflects the integration of biodiversity into cultural identity and the transmission of collective values. This raises the possibility that the economic muscle of the sport industry could translate its symbolic capital into tangible commitments to biodiversity conservation. Those who have had the privilege of travelling in remote areas might have…
Under the sea where there is little or no light, the foraging, communication, and orientation of whales and many other marine animals depend on sound. But increasing human activity has transformed the soundscape of seas and oceans. This change affects the behaviour of species and presents challenges in managing a problem of global scale. Many…
Those of us living with cats share our homes with an ancestral predator, one adapted for hunting and the frequent, exclusive consumption of meat. These instincts become fully activated outside the domestic environment, where cats pose a global threat to wildlife. Pets are family. We celebrate their arrival with the same joy as a grand…
ConservationBytes.com 