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An unexpected journey (of eels)

29 05 2023

The way that eels migrate along rivers and seas is mesmerising. There has been scientific agreement since the turn of the 20^th 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 (i lecocephalus 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 (ii glass phase) that enters wetlands and estuaries, and travels up the rivers as it gains weight and pigment (iii yellow 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 (iv silver 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 20^th 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 19^th 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).

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Tags: Anguilla, CITES, European Union, fish migration, hydroelectric dams, ICES, migration, Overfishing, Sargasso Sea
Categories : aquaculture, connectivity, conservation, decline, ecology, environmental policy, Europe, exploitation, fish, fisheries, food, habitat loss, harvest, illegal fishing, impact, IUU fishing, management, marine, metapopulation, recovery, threatened species

Influential conservation papers of 2022

3 01 2023

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.

Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals — “… this paper adds a much-needed perspective to the status of genetic diversity and adaptive potential in contemporary populations.“

Habitat, geophysical, and eco-social connectivity: benefits of resilient socio-ecological landscapes — “… distinguishes four distinct but interrelated types of connectivity: landscape, habitat, geophysical, and eco-social connectivity, of which the fourth type is new. The authors discuss how these different types of connectivity are related to ecosystem services and disservices, and how they interact with each other to influence landscape sustainability issues.“

Glyphosate impairs collective thermoregulation in bumblebees — “… low-dose glyphosate, combined with global increases in temperature, converge to disrupt homeostatic regulation in bee colonies. This is a crucial revelation for understanding the loss of bees across the globe, as they serve as major pollinators in nature and agriculture.“

Human disturbances affect the topology of food webs — “… provides great opportunities for the study of food web structures, their dynamics and stability under different human influences.“

A comprehensive database of amphibian heat tolerance — “… provides estimates of amphibian upper thermal limits – a relevant trait for assessing the vulnerability of this highly-threatened group of ectotherms to rising temperatures – derived from thousands of experimental studies.”

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Categories : alien species, biodiversity, birds, climate change, climate shift, community ecology, connectivity, conservation, conservation biology, conservation ecology, coral reefs, deforestation, disease, ecology, ecosystem, ecosystem services, environmental policy, extinction, fish, fragmentation, frog, genetic diversity, genetics, habitat loss, invasive species, management, marine, marine protected area, modelling, monitoring, Murray-Darling, ocean, population dynamics, predator, protected area, recovery, research, restoration, science, seagrass, sustainability, synergies, threatened species, top-down ecology, trophic cascades, tropical, vegetation

Influential conservation papers of 2021

5 01 2022

Following my annual tradition, I present the retrospective list of the ‘top’ 20 influential papers of 2021 as assessed by experts in Faculty Opinions (formerly known as F1000). These are in no particular order. See previous years’ lists here: 2020, 2019, 2018, 2017, 2016, 2015, 2014, and 2013.

Amazonia as a carbon source linked to deforestation and climate change — “… confirms what the sparse forest inventory has suggested, that climate change and land-use change is driving Amazonian ecosystems toward carbon sinks. … the research team provides a robust estimate of the carbon dynamics of one of the world’s most important ecosystems and provides insights into the role of land use change and potentials for mitigating direct carbon losses in the future.“

Organic and conservation agriculture promote ecosystem multifunctionality — “… a very clear insight into the trade-offs between the different ecosystem services and indicate that yield and product quality are lower in organic systems compared to conventional systems, yet organic systems have higher economic performance due to higher product prices and subsidies.“

Biodiversity of coral reef cryptobiota shuffles but does not decline under the combined stressors of ocean warming and acidification — “… even with similar richness, community function is very likely to be perturbed by ocean warming/acidification with unpredictable impacts on economically important species such as fish and corals.“

Local conditions magnify coral loss after marine heatwaves — “… show that climate-induced coral loss is greater in areas with elevated seaweed abundance and elevated sea urchin densities, both of which commonly result from local overfishing … effective local management can synergize with global efforts to mitigate climate change and help coral reefs survive the Anthropocene.“

Large ecosystem-scale effects of restoration fail to mitigate impacts of land-use legacies in longleaf pine savannas — “… while restoration can have major benefits in longleaf savannas, land-use legacies have clear effects on many aspects of the ecosystem.“

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Tags: biodiversity, conservation, conservation biology, ecological function, ecology, Ecosystem, function, restoration, top 20
Categories : agriculture, alien species, biodiversity, carbon, climate change, conservation, coral reefs, deforestation, economics, ecosystem, ecosystem function, ecosystem services, evolution, extinction, fish, fisheries, food, fragmentation, habitat loss, invasive species, protected area, reforestation, restoration

Remote areas not necessarily safe havens for biodiversity

16 12 2021

The intensity of threats to biodiversity from human endeavour becomes weaker as the distance to them increases.

As you move away from the big city to enjoy the countryside, you’ll notice the obvious increase in biodiversity. Even the data strongly support this otherwise subjective perception — there is a positive correlation between the degree we destroy habitat, harvest species, and pollute the environment, and the distance from big cities.

Remote locations are therefore usually considered safe havens and potential reservoirs for biodiversity. But our new study published recently in Nature Communications shows how this obvious pattern depicts only half of the story, and that global conservation management and actions might benefit from learning more about the missing part.

Communities are not just lists of individual species. Instead, they consist of complex networks of ecological interactions linking interdependent species. The structure of such networks is a fundamental determinant of biodiversity emergence and maintenance. However, it also plays an essential role in the processes of biodiversity loss. The decline or disappearance of some species might have detrimental —often fatal — effects on their associates. For example, a parasite cannot survive without its hosts, as much as a predator will starve without prey, or a plant will not reproduce without pollinators.

Events where a species disappears following the loss of other species on which it depends are known as co-extinctions, and they are now recognised as a primary driver of the ongoing global biodiversity crisis. The potential risk stemming from ecological dependencies is a major concern for all ecological systems.

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Tags: climate change, coral reefs, coral-reef fishes, ecological networks, Fish, Giovanni Strona, Trophic cascade
Categories : biodiversity, bottom-up ecology, climate change, community ecology, connectivity, conservation, conservation biology, coral reefs, ecology, extinction, fish, fisheries, marine, marine protected area, modelling, planning, predation, predator, top-down ecology, tropical

Losing half of tropical fish species as corals disappear

30 06 2021

When snorkelling in a reef, it’s natural to think of coral colonies as a colourful scenography where fish act in a play. But what would happen to the fish if the stage went suddenly empty, as in Peter Brook’s 1971 Midsummer Night’s Dream? Would the fish still be there acting their roles without a backdrop?

This question is not novel in coral-reef science. Ecologists have often compared reef fish diversity and biomass in selected localities before and after severe events of coral mortality. Even a temporary disappearance of corals might have substantial effects on fish communities, sometimes resulting in a local disappearance of more than half of local fish species.

Considering the multiple, complex ways fish interact with — and depend on — corals, this might appear as an obvious outcome. Still, such complexity of interactions makes it difficult to predict how the loss of corals might affect fish diversity in specific contexts, let alone at the global scale.

Focusing on species-specific fish-coral associations reveals an inconsistent picture with local-scale empirical observations. When looking at the fraction of local fish diversity that strictly depends on corals for food and other more generic habitat requirements (such as shelter and reproduction), the global picture suggests that most fish diversity in reef locality might persist in the absence of corals.

The mismatch between this result and the empirical evidence of a stronger coral dependence suggests the existence of many hidden ecological paths connecting fish to corals, and that those paths might entrap many fish species for which the association to corals is not apparent.

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Tags: climate change, coral reefs, corals, extinction, Global warming, reef fish
Categories : biodiversity, bottom-up ecology, climate change, conservation, coral reefs, decline, ecology, extinction, extinction debt, fish, function, habitat loss, marine, research, top-down ecology, trophic cascades

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

19 04 2021

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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Tags: alien species, Economics, environmental economics, invasive alien spcies, invasive species, weeds
Categories : Africa, agriculture, alien species, Australia, biodiversity, conservation, disease, environmental economics, environmental policy, fish, health, invasive species, management, predator

How to avoid reduce the probability of being killed by a shark

31 03 2021

Easy. Don’t go swimming/surfing/snorkelling/diving in the ocean.

Sure, that’s true, but if you’re like many Australians, the sea is not just a beautiful thing to look at from the window, it’s a way of life. Trying telling a surfer not to surf, or a diver not to dive. Good luck with that.

A few years ago, I joined a team of super-cool sharkologists led by Charlie ‘Aussie-by-way-of-Belgium shark-scientist extraordinaire‘ Huveneers, and including Maddie ‘Chomp’ Thiele and Lauren ‘Acid’ Meyer — to publish the results of some of the first experimentally tested shark deterrents.

It turns out that many of the deterrents we tested failed to show any reduction in the probability of a shark biting, with only one type of electronic deterrent showing any effect at all (~ 60% reduction).

Great. But what might that mean in terms of how many people could be saved by wearing such electronic deterrents? While the probability of being bitten by a shark is low globally, even in Australia (despite public perceptions), we wondered if the number of lives saved and injuries avoided was substantial.

In a new paper just published today in Royal Society Open Science, we attempted to answer that question.

To predict how many people could avoid shark bites if they were using properly donned electronic deterrents that demonstrate some capacity to dissuade sharks from biting, we examined the century-scale time series of shark bites on humans in Australia. This database — the ‘Australian Shark Attack File‘ — is one of the most comprehensive databases of its kind.

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Categories : Australia, behaviour, biodiversity, conservation, ecology, environmental policy, fish, human-wildlife conflict, marine, modelling, ocean, predation, predator, research, shark, water

Plan B: COVID-19 challenges for field-based PhD students

8 12 2020

Originally published on the GEL.blog

Blistering heat, pouring rain, finding volunteers, submitting field-trip forms, forgetting equipment, data sheets blowing away in the wind — a field-based research project is hard at the best of times. Add white sharks into the mix and you start to question whether this project is even possible. These were some of my realisations when I started my Honours year studying shark deterrents.

A specific memory from my first field expedition was setting off on a six-day boat trip with the comfortable sight of land getting smaller and smaller, in an already rough ocean, to find one of the most feared fish in the sea, the white shark. I was intimidated, but also excited.

Over the next few days reality set in and I experienced the true challenges of working in the field. When there were no sharks around, I had to concentrate on the bait line for hours in anticipation of a sudden ambush. When there were sharks around, it was all systems go and there was no room for error — not with a fish of this size. It didn’t matter how tired or seasick I was, the data had to be collected.

When I found out that I had been offered a field-based PhD extending my shark-deterrent research from my Honours, other than being over-the-moon, I knew I had a big few years ahead of me. I immediately began preparing mentally for the challenges that came along with my field-based research. Particularly the long periods of time I knew I would spend away from home and my family.

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Tags: academia, career, contingency planning, COVID, COVID-19, fieldwork, PhD, PhDchat, preparedness, student, student life
Categories : ecology, environmental science, fish, marine, research, science, shark, South Australia, water

Successful movers responding to climate change

16 06 2020

tropical fishes range shifts Ecologists often rely on measuring certain elements of a species’ characteristics, behaviour, or morphology to determine if these — what we call ‘traits’ — give them certain capacities to exploit their natural environments. While sometimes a bit arbitrarily defined, the traits that can be measured are many indeed, and sometimes they reveal rather interesting elements of a species’ resilience in the face of environmental change.

As we know, climate change is changing the way species are distributed around the planet, for the main (and highly simplified) reason that the environments in which they’ve evolved and to which they have adapted are changing.

In the simplest case, a warming climate means that there is a higher and higher chance you’ll experience temperatures that really don’t suit you that well (think of a koala or a flying fox baking in a tree when the thermometer reads +45° in the shade). Just like you seeking those nice, air-conditioned spaces on a scorcher of a day, species like to move to where conditions are more acceptable to their particular physiologies and behaviours.

When they can’t change fast enough, they go extinct.

Ecologists use life-history traits to predict which species have the highest probability of moving to new areas in response to climate change. Most studies into this phenomenon have largely ignored that range shifts in fact occur in sequential stages: (1) the species arrives in a new place for the first time, (2) its population increases in size (and extent), and (3) it can continue to persist in the new spot. Read the rest of this entry »

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Tags: Biogeography, climate change, Fish, marine fishes, native invasive species, range shifts, species' traits, traits, tropical fish
Categories : alien species, Australia, behaviour, bioclimatic envelope, biogeography, climate change, climate shift, coasts, community ecology, coral reefs, ecology, ecosystem, extinction, fish, food, function, invasive species, marine, monitoring, southern Australia, tropical

Amphibian conservation in a managed world

1 04 2020

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 »

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Tags: amphibian, conservation, conservation evidence, environmental flow, flow, frog, pump, restoration, salamander, spray, spraying, Toad, water, wetlands
Categories : amphibian, climate change, conservation, conservation biology, disease, drought, environmental policy, extinction, fish, frog, habitat loss, management, pollution, predation, predator, recovery, restoration, water

In pursuit of an ecological resilience in the Anthropocene

3 03 2020

An excerpt from Alejandro Frid‘s new book, Changing Tides: An Ecologist’s Journey to Make Peace with the Anthropocene (published first in Sierra, with photos courtesy of New Society Publishers)

—

The birth of my daughter, in 2004, thrust upon me a dual task: to be scientifically realistic about all the difficult changes that are here to stay, while staying humanly optimistic about the better things that we still have.

By the time my daughter turned eleven, I had jettisoned my nostalgia for the Earth I was born into in the mid-196os—a planet that, of course, was an ecological shadow of Earth 100 years before, which in turn was an ecological shadow of an earlier Earth. The pragmatist in me had embraced the Anthropocene, in which humans dominate all biophysical processes, and I ended up feeling genuinely good about some of the possible futures in which my daughter’s generation might grow old.

It was a choice to engage in a tough situation. An acknowledgement of rapid and uninvited change. A reaffirmed commitment to everything I have learned, and continue to learn, as an ecologist working with Indigenous people on marine conservation. Fundamental to this perspective is the notion of resilience: the ability of someone or something—a culture, an ecosystem, an economy, a person—to absorb shocks yet still maintain their essence.

But what is essence? Read the rest of this entry »

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Tags: Anthropocene, biodiversity, extinction
Categories : anthropocene, biodiversity, birds, climate change, conservation, deforestation, ecology, environmental policy, ethics, extinction, fish, habitat loss

Influential conservation ecology papers of 2019

24 12 2019

As I’ve done for the last six years, I am publishing a retrospective list of the ‘top’ 20 influential papers of 2019 as assessed by experts in F1000 Prime (in no particular order). See previous years’ lists here: 2018, 2017, 2016, 2015, 2014, and 2013.

Decline of the North American avifauna — … the first comprehensive assessment of population change in the North American avifauna.

Scientists’ warning to humanity: microorganisms and climate change — … [highlights] the crucial role of microbial transformations in determining set points for sea temperature, pH and ocean productivity … [identifies] microbial activity as the “life support system of the biosphere”.

(Note: Lots of people hated this one, basically because it appears to be severely flawed; nonetheless, it received several recommendations on F1000): The global tree restoration potential — … illustrates the substantial potential of capturing some of the excess carbon dioxide present in the earth’s atmosphere by planting trees.

Managing the middle: a shift in conservation priorities based on the global human modification gradient — … probably the best global assessment of spatial extent of human modification of natural terrestrial environments published to date.

Five decades of northern land carbon uptake revealed by the interhemispheric CO₂ gradient — … [concludes] that northern hemisphere [sic] vegetation and soil account for the majority of the terrestrial carbon sink, rather than tropical forests (not trying to display too many sour grapes here, but we’ve already reported this for the boreal forest, and they didn’t even bother to cite us — sad panda)

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Tags: agriculture, biodiversity, birds, carbon, carbon uptake, climate change, climate emergency, CO2, conservation, declines, drought, extinction, Fish, fisheries, forests, insects, marine ecology, microorganisms, pesticides, range edges, trees, urban biodiversity, wilderness
Categories : agriculture, anthropocene, biodiversity, biogeography, biowealth, birds, carbon, climate change, climate shift, community ecology, connectivity, conservation, conservation biology, conservation ecology, decline, deforestation, demography, ecology, economics, ecosystem, ecosystem function, ecosystem services, environmental policy, environmental science, exploitation, extinction, extinction debt, fish, fisheries, function, habitat loss, harvest, marine, planning, pollution, protected area

“Overabundant” wildlife usually isn’t

12 07 2019

koalacrosshairs Late last year (10 December) I was invited to front up to the ‘Overabundant and Pest Species Inquiry’ at the South Australian Parliament to give evidence regarding so-called ‘overabundant’ and ‘pest’ species.

There were the usual five to six Ministers and various aides on the Natural Resources Committee (warning here: the SA Parliament website is one of the most confusing, archaic, badly organised, and generally shitty government sites I’ve yet to visit, so things require a bit of nuanced searching) to whom I addressed on issues ranging from kangaroos, to dingoes, to koalas, to corellas. The other submissions I listened to that day were (mostly) in favour of not taking drastic measures for most of the human-wildlife conflicts that were being investigated.

Forward seven months and the Natural Resources Committee has been reported to have requested the SA Minister for Environment to allow mass culling of any species (wildlife or feral) that they deem to be ‘overabundant’ or a ‘pest’.

So, the first problem is terminological in nature. If you try to wade through the subjectivity, bullshit, vested interests, and general ignorance, you’ll quickly realise that there is no working definition or accepted meaning for the words ‘overabundant’ or ‘pest’ in any legislation. Basically, it comes down to a handful of lobbyists and other squeaky wheels defining anything they deem to be a nuisance as ‘overabundant’, irrespective of its threat status, ecological role, or purported impacts. It is, therefore, entirely subjective, and boils down to this: “If I don’t like it, it’s an overabundant pest”. Read the rest of this entry »

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Tags: dingo, environment, fur seals, Government of South Australia, Kangaroo, koala, little corella, Natural Resources Committee, South Australia
Categories : alien species, animal welfare, Australia, biodiversity, climate change, community ecology, conservation, decline, dingo, ecology, ecosystem, ecosystem function, environmental policy, exploitation, fish, fisheries, harvest, human-wildlife conflict, impact, invasive species, kangaroo, management, meso-predator release, predation, predator, science, South Australia, sustainability, threatened species, top-down ecology

How to fix a broken river

5 04 2019

murraycod

It seems that most of what I do these days is measure, model, or otherwise quantify environmental damage. While I dabble in restoration, occasionally I’m involved in a project that really can make a positive difference.

If you’re an Australian, you’ll know a thing or two about just how much of a clusterfuck our biggest river system has turned into. From mismanagement, to outright theft, to lobbyist-driven over-exploitation, to climate change itself, the Murray-Darling system is now in a right mess.

So, I’ll pretext this post with a caveat — no amount of ecological restoration can ‘fix’ a compromised river if there’s no water in it. Goes without saying, really.

But, if you do have water, then there are things one can do to promote populations of various creatures living in it, like fish.

Dubbed the ‘honeypot effect’ — we have just shown that providing woody habitat, or ‘snags’, for native fish in the Murray River increases population size. Read the rest of this entry »

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Tags: aquatic, ecological restoration, ecology, golden perch, Murray cod, Murray-Darling, rehabilitation, restoration, snags
Categories : Australia, conservation, conservation ecology, fish, fisheries, Murray cod, Murray River, Murray-Darling, restoration, River Murray, South Australia, southern Australia, water

Influential conservation ecology papers of 2018

17 12 2018

For the last five years I’ve published a retrospective list of the ‘top’ 20 influential papers of the year as assessed by experts in F1000 Prime — so, I’m doing so again for 2018 (interesting side note: six of the twenty papers highlighted here for 2018 appear in Science magazine). See previous years’ posts here: 2017, 2016, 2015, 2014, and 2013.

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Tags: biodiversity hotspots, biodiversity loss, climate breakdown, climate change, cognition, coral reefs, disease, fieldwork, Fish, fisheries, fishing impacts, Great Barrier Reef, killer whales, mammals, nuisance species, plastics, predators, productivity, richness-productivity relationship, sharks, Species richness, wild areas
Categories : anthropocene, aquaculture, Australia, biodiversity, biowealth, carbon, climate change, climate shift, community ecology, connectivity, conservation, conservation biology, conservation ecology, coral reefs, decline, deforestation, demography, ecology, economics, ecosystem, ecosystem function, ecosystem services, environmental policy, environmental science, exploitation, extinction, extinction debt, fish, fisheries, food, fragmentation, function, habitat loss, harvest, human overpopulation, invasive species, management, marine, marine protected area, modelling, pollination, pollution

Personal deterrents can reduce the risk of shark bites

19 06 2018

Photo: Charlie Huveneers

A little over a week ago, shark ecologist, Charlie Huveneers, and I attempted to write an article in The Conversation about a report we co-wrote regarding the effectiveness of personal shark-deterrent devices (see below for more on the report itself). It’s a great little story, with both immediate policy implications for human safety and great, big potential improvements to shark conservation in general (i.e., if sharks kill fewer people, then perhaps governments would be less inclined to invokes stupid laws to kill sharks). Indeed, sharks aren’t doing very well around the world, mainly because of over-harvest and persecution from unfounded fear.

Anyway, all was going swimmingly until our editor at The Conversation suddenly decided that they wouldn’t publish the piece based on the following funding disclaimer that we had submitted with the article:

This project was funded by the New South Wales Department of Primary Industries Shark Management Strategy Competitive Annual Grants Program, the Government of South Australia, Ocean Guardian Pty Ltd, and the Neiser Foundation. We openly and transparently declare that Ocean Guardian contributed financially to the study, but that Ocean Guardian was not involved in the study design or implementation, nor did they have access to the data post-collection. Nor did Ocean Guardian provide input into data analysis, interpretation, writing of the report, or the conclusions drawn. The study design followed a protocol developed for a previous study, which was not funded by Ocean Guardian. In summary, Ocean Guardian had no opportunity to influence any aspect of the study or its conclusions, apart from providing some financial support to realise the field project (e.g., boat hire, equipment purchase, etc.) in the same manner as the other funding agencies. The South Australian cage-diving industry provided logistical support during the testing of the deterrents.

The long and short of The Conversation‘s negative decision was that one of the companies contributed financially to project. However, as we stated above, they had absolutely no influence in the subsequent experimental design, data collection, analysis, interpretation or report writing.

While normally I’m a big fan of The Conversation, I really think they dropped the ball with this one. Their decision was illogical and unsupported for five main reasons:

There were many funding partners involved, and the Ocean Freedom contribution was in no way the major or even majority share of funding.
Other companies with devices tested could have contributed, but only Ocean Freedom offered.
The study was commissioned by a state government agency (New South Wales Department of Primary Industries), which is not a commercial entity.
As stated in our disclosure, there was no opportunity for manipulating experimental design, data ownership, or post-collection analysis or writing that could have influenced the results, by any funders or contributors.
The disclosure is open, honest, comprehensive and in every way truthful.

So, I’m more than just a little disappointed — and my opinion of the organisation has dropped considerably. That, with the constant barrage of donation requests they send makes me think twice about their journalistic integrity. I challenge others to think carefully before giving them any money.

Regardless, let’s move on to the article itself (which I can publish freely here without the Draconian oversight of The Conversation):

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Many things might explain why the number of shark bites appear to be increasing. However, the infrequent occurrence of such events makes it nearly impossible to determine why. Recently, an atypically high rate of shark bites occurred in Western Australia in 2010-2011 and on the north coast of New South Wales in 2015-2016. These highly publicised events — often sensationalised in both traditional and social media — have pressured governments to implement new measures to reduce the risk of shark bites.

The rising pressure to do something to reduce shark bites has prompted the recent development or commercial release of many new personal shark deterrents. Yet, most of these devices lack any rigorous scientific assessment of their effectiveness, meaning that some manufacturers have made unfounded claims about how much their devices dissuade sharks from attacking humans.

However, if a particular type of commercially available shark deterrent happens to be less effective (or completely ineffective) as advertised, it can give users a false sense of security, potentially encouraging some to put themselves at greater risk than is necessary. For example, some surfers and spearfishers probably ignore other mitigation measures, such as beach closures, because they ‘feel safe’ when wearing these products.

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Tags: carcharinids, Carcharodon carcharias, Chillax Wax, conflict of interest, Experiment, great white shark, human-wildlife conflict, journalism, media, Ocean Freedom, Ocean Guardian, Rpela, shark, shark deterrents, Sharkbanz, sharks, surfer safety, surfing, The Conservation, white pointer
Categories : Australia, conservation, conservation biology, environmental policy, fish, human-wildlife conflict, management, marine, ocean, predation, shark

What Works in Conservation 2018

23 05 2018

Do you have a copy of this book? If not, why not?

This book is free to download. This book contains the evidence for the effectiveness of over 1200 things you might do for conservation. If you don’t have a copy, go and download yourself a free one here, right now, before you even finish reading this article. Seriously. Go. You’ll laugh, you’ll cry, it’ll change your life.

Why you’ll laugh

OK, I may have exaggerated the laughing part. ‘What Works in Conservation 2018’ is a serious and weighty tome, 660 pages of the evidence for 1277 conservation interventions (anything you might do to conserve a species or habitat), assessed by experts and graded into colour-coded categories of effectiveness. This is pretty nerdy stuff, and probably not something you’ll lay down with on the beach or dip into as you enjoy a large glass of scotch (although I don’t know your life, maybe it is).

But that’s not really what it’s meant for. This is intended as a reference book for conservation managers and policymakers, a way to scan through your possible solutions and get a feel for those that are most likely to be effective. Once you have a few ideas in mind, you can follow the links to see the full evidence base for each study at conservationevidence.com, where over 5000 studies have been summarised into digestible paragraphs.

The book takes the form of discrete chapters on taxa, habitats or topics (such as ‘control of freshwater invasives’). Each chapter is split into IUCN threat categories such as ‘Agriculture’ or ‘Energy production and mining’. For each threat there are a series of interventions that could be used to tackle it, and for each of these interventions the evidence has been collated. Experts have then graded the body of the evidence over three rounds of Delphi scoring, looking at the effectiveness, certainty in the evidence (i.e., the quality and quantity of evidence available), and any harms to the target taxa. These scores combine to place each intervention in a category from ‘Beneficial’ to ‘Likely to be ineffective or harmful’. Read the rest of this entry »

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Tags: conservation, conservation evidence, ecology, intervention, management, managers, policymakers, rehabilitation, restoration, University of Cambridge
Categories : amphibian, biodiversity, birds, captive breeding, climate change, conservation, conservation biology, conservation ecology, ecology, ecosystem, ecosystem function, ecosystem services, environmental policy, extinction, fish, fragmentation, function, governance, impact, invasive species, management, protected area, research, science, threatened species

Predicting sustainable shark harvests when stock assessments are lacking

26 03 2018

I love it when a good collaboration bears fruit, and our latest paper is a good demonstration of that principle.

It all started a few years ago with an ARC Linkage Project grant we received to examine how the whaler shark fishing industry in Australia might manage its stocks better.

As I’m sure many are aware, sharks around the world aren’t doing terribly well (surprise, surprise — yet another taxon suffering at the hands of humankind). And while some populations (‘stocks’, in the dissociative parlance of the fishing industry) are doing better than others, and some countries have a better track record in managing these stocks than others, the overall outlook is grim.

One of the main reasons sharks tend to fair worse than bony fishes (teleosts) for the same fishing effort is their ‘slow’ life histories. It doesn’t take an advanced quantitative ecology degree to understand that growing slowly, breeding late, and producing few offspring is a good indication that a species can’t handle too much killing before populations start to dwindle. As is the case for most large shark species, I tend to think of them in a life-history sense as similar to large terrestrial mammals.

Now, you’d figure that a taxon with intrinsic susceptibility to fishing would have heaps of good data with which managers could monitor catches and quotas so that declines could be avoided. However, the reality is generally the inverse, with many populations having poor information regarding vital rates (e.g., survival, fertility), age structure, density feedback characteristics, and even simple estimates of abundance. Without such key information, management tends to be ad hoc and often not very effective. Read the rest of this entry »

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Tags: bronze whaler sharks, bronze whalers, bronzies, Carchcarinus brachyurus, chondrichthyan, commercial fishing, copper shark, demographic model, fishing, global sensitivity analysis, Latin hypercube, sustainable fisheries
Categories : Australia, conservation, environmental policy, exploitation, fish, fisheries, genetics, harvest, management, marine, ocean, population dynamics, population viability analysis, shark

Penguins cheated by ecosystem change

13 03 2018

Jorge Drexler sings “… I was committed not to see what I saw, but sometimes life is more complex than what it looks like …”*. This excerpt by the Oscar-winning Uruguayan singer seems to foretell the theme of this blog: how the ecological complexity of marine ecosystems can elicit false signals to their predators. Indeed, the fidelity of marine predators to certain feeding areas can turn demographically detrimental to themselves when the amount of available food shrinks. A study of jackass penguins illustrates the phenomenon in a context of overfishing and ocean warming.

Adult of jackass penguin (Spheniscus demersus) from Robben Island (South Africa) — in the inset, one of the first juveniles released with a satellite transmitter on its back. The species is ‘Endangered’ under IUCN’s criteria (28), following a recent halving of the total population currently estimated at ~ 80,000 adults. Jackass penguins are the only penguins living in Africa, and owe their common name to their vocalisations (you can hear their braying sounds here); adults are ~ 50 cm tall and weigh ~ 3 kg. Photos courtesy of Richard Sherley.

Surface temperature, dissolved oxygen, acidity and primary productivity are, by and large, the top four environmental factors driving the functionality of marine ecosystems (1). Growing scientific evidence supports the idea that anthropogenic warming of the atmosphere and the oceans correlates with this quartet (2). For instance, marine primary productivity is enhanced by increased temperatures (3), but a warmer sea surface intensifies stratification, i.e., stacked layers of seawater with contrasting physical and chemical properties.

In coastal areas experiencing ‘upwelling’ (where winds displace surface water, allowing deep water laden with nutrients to reach the euphotic zone where plankton communities feast), stratification weakens upwelling currents and, in turn, limits the growth of plankton (4) that fuels the entire trophic web, including our fisheries. The study of these complex trophic cascades is particularly cumbersome from the perspective of large marine predators because of their capacity to move long distances, from hundreds to thousands of kilometres (5), with strong implications for their conservation (6).

With those caveats in mind, Richard Sherley and colleagues satellite-tracked the movement of 54 post-fledged, juvenile jackass penguins (Spheniscus demersus) for 2-3 years (7). All individuals had been hatched in eight colonies (accounting for 80% of the global population), and were equipped with platform terminal transmitters. Jackass penguins currently nest in 28 island and mainland locations between South Africa and Namibia. Juveniles swim up to 2000 km in search of food and, when approaching adulthood, return to their native colonies where they reproduce and reside for the remainder of their lives (watch individuals swimming here).

The natural history of this species is linked to the Southern Hemisphere’s trade winds (‘alisios’ for Spanish speakers), which blow from the southeast to the tropics. In the South Atlantic, trade winds sustain the Benguela Current, the waters of which surface from some 300 m of depth and fertilise the marine ecosystems stretching from the Western coasts of South Africa to Angola (8). Read the rest of this entry »

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Tags: anchovy, Benguela, climate change, fisheries, food web, Global warming, jellies, jellyfication, Namibia, Overfishing, penguin, penguins, pilchard, South Africa, upwelling
Categories : Africa, behaviour, birds, climate change, climate shift, coasts, decline, ecology, ecosystem, ecosystem function, fish, fisheries, food, function, harvest, impact, research, science, trophic cascades

Offshore Energy & Marine Spatial Planning

22 02 2018

I have the pleasure (and relief) of announcing a new book that’s nearly ready to buy, and I think many readers of CB.com might be interested in what it describes. I know it might be a bit premature to announce it, but given that we’ve just finished the last few details (e.g., and index) and the book is ready to pre-order online, I don’t think it’s too precocious to advertise now.

A little history is in order. The brilliant and hard-working Katherine Yates (now at the University of Salford in Manchester, UK) approached me back in 2014 to assist her with co-editing the volume that she wanted to propose for the Routledge Earthscan Ocean series. I admit that I reluctantly agreed at the time, knowing full well what was in store (anyone who has already edited a book will know what I mean). Being an active researcher in energy and biodiversity (perhaps not so much on the ‘planning’ side per se) certainly helped in my decision.

And yes, there were ups and downs, and sometimes it was a helluva lot of work, but Katherine certainly made my life easier, and she has finally driven the whole thing to completion. She deserves most of the credit.

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