Wildlife trade increases pathogen transmission

University of Lausanne

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A study conducted at the Department of Ecology and Evolution of the University of Lausanne (Unil) quantifies the impact of wildlife trade on the exchange of germs and parasites between animals and humans. It was published on 9 April 2026 in the journal Science.

Hedgehogs, elephants, pangolins, bears or fennec foxes: many wild species are sold as pets, hunting trophies, for traditional medicine, biomedical research, or for their meat or fur. These practices, whether legal or illegal, concern one quarter of all mammal species.

The team led by Cleo Bertelsmeier, Associate Professor at the Department of Ecology and Evolution (DEE) of the Faculty of Biology and Medicine at Unil, assessed the role of international wildlife trade in the transmission of pathogens between animals and humans. While this link has seemed obvious since Covid-19 – reminding that the sale of animals at the Wuhan market was singled out – “no precise quantification had been carried out until now,” explains Jérôme Gippet, first author of the study published on 9 April 2026 in Science.

Forty years of trade data analysed

The team combined forty years of legal and illegal wildlife import-export data with compilations of host–pathogen relationships. Their analyses, conducted in collaboration with U.S. researchers (Yale University, University of Maryland and University of Idaho), led to the following result: wild mammals that are traded are 1.5 times more likely to share infectious agents with humans than those that are not involved in trade. “In other words, these species have a 50% higher probability of sharing at least one virus, bacterium, fungus or parasite with us.” And that is not all: the risk is even higher when species are traded illegally or alive (for example as exotic pets).

The most striking finding according to the research team is that “the length of time an animal has been present in trade plays a key role: on average, a species shares one additional pathogen with humans for every ten-year period spent on the market,” emphasizes Jérôme Gippet, former postdoctoral researcher at the DEE, now at the University of Fribourg.

Wildlife in all its forms

The work focuses on wild mammals, meaning species that have not been domesticated and on which humans have therefore not exerted selective pressure, unlike cats, dogs, cattle or camels. These may be individuals captured from the wild or bred in captivity, for example for fur production. This category also includes new exotic pets – fennec foxes, otters, African pygmy hedgehogs, leopard cats or sugar gliders, to name but a few – whose buying and selling are fuelled by their popularity on social media. The data analysed cover both the trade in live specimens and in animal-derived products (fur, skins, scales, horns, etc.).

“It is important to understand that the probability of being infected by playing a piano with ivory keys or wearing fur is almost nonexistent. The problem lies at the beginning of the chain: someone had to hunt the animal, skin it, transport it…,” explains Jérôme Gippet. “Thus, even if the danger is not immediate, our consumption choices indirectly fuel the transmission of pathogens to humans. This calls our purchasing practices into question,” adds Cleo Bertelsmeier, who led the study.

At the intersection of ecology and public health

The team led by Cleo Bertelsmeier initially became interested in wildlife trade because it is a source of biological invasions (see related news in French). Individuals can escape or be released into the wild and cause harm to local ecosystems. But this activity can also have two other consequences: first, the risk of species extinction due to overexploitation of natural populations; second, the risk of pathogen exchange with humans, which is the focus of this latest Science publication, a phenomenon that can lead to epidemics or even pandemics. Covid-19 is only one example among others: in 2003, the United States notably faced an outbreak of monkeypox transmitted by prairie dogs sold as pets.

Strengthening biosurveillance

The results of the study highlight the need to improve biosurveillance of animals and animal-derived products in order to detect infectious agents and assess their potential for transmission to humans. Currently, the main multilateral agreement governing international trade in wild species, CITES, focuses exclusively on preventing extinction.

“Our finding that wild mammals share, on average, one additional pathogen with humans for every decade of presence on the global market highlights that the number of contacts plays a decisive role. To reduce disease emergence, these opportunities for encounters must be limited, and therefore the overall volume of trade,” states Jérôme Gippet.

“In my view, our work clearly shows how fundamental research can shed light on public health issues. It provides key elements to better understand host–pathogen dynamics and prevent future epidemics,” concludes Cleo Bertelsmeier.

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Journal

Science

DOI

10.1126/science.adw5518 

Article Title

Wildlife trade drives animal-to-human pathogen transmission over 40 years

Article Publication Date

9-Apr-2026

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• Wildlife trade increases pathogen transmission
  (University of Lausanne)

 

World's largest known chimpanzee community demonstrates rare instance of division and deadly violence

University of Texas at Austin

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The largest group of wild chimpanzees known to scientists has permanently split in two. In a study published in Science, researchers from The University of Texas at Austin and other institutions report the first clearly documented permanent fission in wild chimpanzees and the sustained intergroup violence that followed. The findings draw on three decades of field observations of the Ngogo chimpanzees of Kibale National Park, Uganda, a population featured in the Netflix documentary series Chimp Empire.

The community was cohesive for the first two decades of research. Individual chimpanzees moved between flexible subgroups, or "clusters," and maintained social ties across the community — a fission-fusion dynamic typical of the species, in which individuals temporarily separate and reunite. In 2015, however, the team witnessed signs of polarization, with the Western and Central clusters increasingly avoiding each other. This shift coincided with a change in the male dominance hierarchy and came one year after the deaths of several adult males who may have functioned as bridges holding the larger community together.

By 2018, the fission was complete. The chimpanzees now belonged to two distinct groups — Western and Central — with separate territories. What followed was a series of lethal attacks by the Western group on members of the Central group. Between 2018 and 2024, researchers observed or inferred with high confidence seven attacks on adult males and 17 on infants.

"What's especially striking is that the chimpanzees are killing former group members," says Aaron Sandel, associate professor of anthropology at UT Austin and the study's lead author. "The new group identities are overriding cooperative relationships that had existed for years."

In many primate species, large groups regularly split into smaller ones, often reducing competition for resources. But in chimpanzees, permanent fissions are extraordinarily rare. Genetic evidence suggests they occur roughly once every 500 years. The only previously reported case took place in the 1970s at Gombe, Tanzania, during Jane Goodall's long-term study. But that case has remained a subject of debate in part because the chimpanzees there were provisioned with food by researchers. At Ngogo, the chimpanzees were never provisioned, and the picture is more complete, thanks to nearly three decades of study by John Mitani, emeritus professor of anthropology at the University of Michigan, and a large team of researchers and Ugandan field staff.

"I would caution against anyone calling this a civil war," says Sandel. "But the polarization and collective violence that we have observed with these chimpanzees may give us insight into our own species."

The authors describe their findings as a challenge to the hypothesis that human warfare, including civil war, is driven primarily by cultural markers of group identity such as ethnic or religious differences.

"If relational dynamics alone can drive polarization and lethal conflict in chimps without language, ethnicity, or ideology, then in humans, those cultural markers might be secondary to something more basic," says Sandel. "If that's true, then we may have the potential to reduce societal conflicts in our personal lives, and that gives me hope. As our paper concludes, it may be in the small, daily acts of reconciliation and reunion between individuals that we find opportunities for peace."

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Journal

Science

DOI

10.1126/science.adz4944 

Article Title

Lethal conflict following group fission in wild chimpanzees

Article Publication Date

9-Apr-2026

Related News Releases

• World's largest known chimpanzee community demonstrates rare instance of division and deadly violence
  (University of Texas at Austin)

Ancient Survivor Reveals Its Secret: First-Ever Egg Of A Mammal Ancestor Discovered

Lystrosaurus embryo within its partially preserved shell , reconstruction of the animal 

CREDIT: Professor Julien Benoit Drawing - Sophie Vrard

April 11, 2026
By Eurasia Review


A remarkable new discovery is shedding light on one of the greatest survival stories in Earth’s history, and answering a decades-old scientific mystery. Lystrosaurus, a hardy, plant-eating mammal ancestor, rose to prominence in the wake of the End-Permian Mass Extinction some 252 million years ago, the most devastating extinction event our planet has ever experienced. While countless species vanished, Lystrosaurus not only survived, but thrived in a world marked by extreme environmental instability, intense heat, and prolonged droughts.

Now, groundbreaking research published in PLoS ONE reveals a discovery that transforms our understanding of this iconic survivor. An international team led by Professor Julien Benoit, Professor Jennifer Botha (Evolutionary Studies Institute, University of the Witwatersrand, South Africa), and Dr Vincent Fernandez (ESRF – The European Synchrotron, France) has identified, for the first time, an egg containing an embryo of Lystrosaurus, dating back approximately 250 million years. This extraordinary fossil represents the first-ever egg discovered from a mammal ancestor, finally answering a long-standing question: Did the ancestors of mammals lay eggs?

The answer is yes.

The researchers suggest these eggs were likely soft-shelled, explaining why they have remained elusive for so long. Unlike the hard, mineralized eggs of dinosaurs, which fossilize readily, soft-shelled eggs rarely preserve, making this find exceptionally rare. But the implications go far beyond reproduction.

“This fossil was discovered during a field excursion I led in 2008, nearly 17 years ago. My preparator and exceptional fossil finder, John Nyaphuli, identified a small nodule that at first revealed only tiny flecks of bone. As he carefully prepared the specimen, it became clear that it was a perfectly curled-up Lystrosaurus hatchling. I suspected even then that it had died within the egg, but at the time, we simply didn’t have the technology to confirm it,” says Professor Botha.

With the advent of advanced synchrotron x-ray CT and the bright X-rays of the ESRF, Professor Benoit and Dr Vincent Fernandez were finally able to unlock the last pieces of the puzzle. Dr Fernandez described the experience as particularly thrilling: “Understanding reproduction in mammal ancestors has been a long-lasting enigma and this fossil provides a key piece to this puzzle. It was essential that we scanned the fossil just right to capture the level of detail needed to resolve such tiny, delicate bones.”

The scans revealed a critical clue. “When I saw the incomplete mandibular symphysis, I was genuinely excited,” says Professor Benoit. “The mandible, the lower jaw, is made up of two halves that must fuse before the animal can feed. The fact that this fusion had not yet occurred shows that the individual would have been incapable of feeding itself.”

The study reveals that Lystrosaurus laid relatively large eggs for its body size. In modern animals, larger eggs typically contain more yolk, providing all the nutrients an embryo needs to develop independently, without parental feeding after hatching. This strongly suggests that Lystrosaurus did not produce milk for its young, unlike modern mammals. Large eggs also offer another crucial advantage: they are more resistant to drying out. In the harsh, drought-prone environment following the extinction, this would have been a critical survival trait. The findings further suggest that Lystrosaurus hatchlings were likely precocial, born at an advanced stage of development. These young animals would have been capable of feeding themselves, escaping predators, and reaching reproductive maturity quickly.

In other words, Lystrosaurus succeeded by living fast and reproducing early.

In a world on the brink, this strategy proved unstoppable. This discovery not only provides the first direct evidence of egg-laying in mammal ancestors but also offers a powerful explanation for how Lystrosaurus came to dominate post-extinction ecosystems. As scientists continue to uncover the biology of ancient survivors, one thing is becoming clear: resilience, adaptability, and reproductive strategy were key to enduring Earth’s darkest chapter, and Lystrosaurus mastered them all.
From the Researchers

“This research is important because it provides the first direct evidence that mammal ancestors, such as Lystrosaurus, laid eggs, resolving a long-standing question about the origins of mammalian reproduction. Beyond this fundamental insight, it reveals how reproductive strategies can shape survival in extreme environments: by producing large, yolk-rich eggs and precocial young, Lystrosaurus was able to thrive in the harsh, unpredictable conditions following the end-Permian mass extinction. In a modern context, this work is highly impactful because it offers a deep-time perspective on resilience and adaptability in the face of rapid climate change and ecological crisis. Understanding how past organisms survived global upheaval helps scientists better predict how species today might respond to ongoing environmental stress, making this discovery not just a breakthrough in palaeontology, but also highly relevant to current biodiversity and climate challenges” Julien Benoit explains. “The opportunity to work at the European Synchrotron Radiation Facility alongside beamline scientists was also an unforgettable part of the journey. The cutting-edge data we generated there allowed us to “see” inside the fossil in extraordinary detail, ultimately revealing that the embryo was still at a pre-hatching stage. That moment, when the pieces all came together, was incredibly rewarding”.

“What makes this work especially exciting is that we were able to quite literally follow in John Nyaphuli’s footsteps, returning to a specimen he discovered nearly two decades ago and finally solve the puzzle he uncovered. At the time, all we had was a beautifully curled embryo, but no preserved eggshell to prove it had died within an egg. Using modern imaging techniques, we were able to answer that question definitively” says Jennifer Botha. “It is also thrilling because this discovery breaks entirely new ground. For over 150 years of South African palaeontology, no fossil had ever been conclusively identified as a therapsid egg. This is the first time we can say, with confidence, that mammal ancestors like Lystrosaurus laid eggs, making it a true milestone in the field”.

Ancient survivor reveals its secret: First-ever egg of a mammal ancestor discovered

250 million year old proto-mammal egg

University of the Witwatersrand

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Lystrosaurus embryo within its partially preserved shell , reconstruction of the animal

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Credit: Pictures - Professor Julien Benoit Drawing - Sophie Vrard

A remarkable new discovery is shedding light on one of the greatest survival stories in Earth’s history, and answering a decades-old scientific mystery. Lystrosaurus, a hardy, plant-eating mammal ancestor, rose to prominence in the wake of the End-Permian Mass Extinction some 252 million years ago, the most devastating extinction event our planet has ever experienced. While countless species vanished, Lystrosaurus not only survived, but thrived in a world marked by extreme environmental instability, intense heat, and prolonged droughts.

Now, groundbreaking research published in PLoS ONE reveals a discovery that transforms our understanding of this iconic survivor. An international team led by Professor Julien Benoit, Professor Jennifer Botha (Evolutionary Studies Institute, University of the Witwatersrand, South Africa), and Dr Vincent Fernandez (ESRF – The European Synchrotron, France) has identified, for the first time, an egg containing an embryo of Lystrosaurus, dating back approximately 250 million years. This extraordinary fossil represents the first-ever egg discovered from a mammal ancestor, finally answering a long-standing question: Did the ancestors of mammals lay eggs?

The answer is yes.

The researchers suggest these eggs were likely soft-shelled, explaining why they have remained elusive for so long. Unlike the hard, mineralized eggs of dinosaurs, which fossilize readily, soft-shelled eggs rarely preserve, making this find exceptionally rare. But the implications go far beyond reproduction.

“This fossil was discovered during a field excursion I led in 2008, nearly 17 years ago. My preparator and exceptional fossil finder, John Nyaphuli, identified a small nodule that at first revealed only tiny flecks of bone. As he carefully prepared the specimen, it became clear that it was a perfectly curled-up Lystrosaurus hatchling. I suspected even then that it had died within the egg, but at the time, we simply didn’t have the technology to confirm it,” says Professor Botha.

With the advent of advanced synchrotron x-ray CT and the bright X-rays of the ESRF, Professor Benoit and Dr Vincent Fernandez were finally able to unlock the last pieces of the puzzle. Dr Fernandez described the experience as particularly thrilling: “Understanding reproduction in mammal ancestors has been a long-lasting enigma and this fossil provides a key piece to this puzzle. It was essential that we scanned the fossil just right to capture the level of detail needed to resolve such tiny, delicate bones.”

The scans revealed a critical clue. “When I saw the incomplete mandibular symphysis, I was genuinely excited,” says Professor Benoit. “The mandible, the lower jaw, is made up of two halves that must fuse before the animal can feed. The fact that this fusion had not yet occurred shows that the individual would have been incapable of feeding itself.”

The study reveals that Lystrosaurus laid relatively large eggs for its body size. In modern animals, larger eggs typically contain more yolk, providing all the nutrients an embryo needs to develop independently, without parental feeding after hatching. This strongly suggests that Lystrosaurus did not produce milk for its young, unlike modern mammals. Large eggs also offer another crucial advantage: they are more resistant to drying out. In the harsh, drought-prone environment following the extinction, this would have been a critical survival trait. The findings further suggest that Lystrosaurus hatchlings were likely precocial, born at an advanced stage of development. These young animals would have been capable of feeding themselves, escaping predators, and reaching reproductive maturity quickly.

In other words, Lystrosaurus succeeded by living fast and reproducing early.

In a world on the brink, this strategy proved unstoppable. This discovery not only provides the first direct evidence of egg-laying in mammal ancestors but also offers a powerful explanation for how Lystrosaurus came to dominate post-extinction ecosystems. As scientists continue to uncover the biology of ancient survivors, one thing is becoming clear: resilience, adaptability, and reproductive strategy were key to enduring Earth’s darkest chapter, and Lystrosaurus mastered them all.

From the Researchers

“This research is important because it provides the first direct evidence that mammal ancestors, such as Lystrosaurus, laid eggs, resolving a long-standing question about the origins of mammalian reproduction. Beyond this fundamental insight, it reveals how reproductive strategies can shape survival in extreme environments: by producing large, yolk-rich eggs and precocial young, Lystrosaurus was able to thrive in the harsh, unpredictable conditions following the end-Permian mass extinction. In a modern context, this work is highly impactful because it offers a deep-time perspective on resilience and adaptability in the face of rapid climate change and ecological crisis. Understanding how past organisms survived global upheaval helps scientists better predict how species today might respond to ongoing environmental stress, making this discovery not just a breakthrough in palaeontology, but also highly relevant to current biodiversity and climate challenges” Julien Benoit explains. “The opportunity to work at the European Synchrotron Radiation Facility alongside beamline scientists was also an unforgettable part of the journey. The cutting-edge data we generated there allowed us to “see” inside the fossil in extraordinary detail, ultimately revealing that the embryo was still at a pre-hatching stage. That moment, when the pieces all came together, was incredibly rewarding”.

“What makes this work especially exciting is that we were able to quite literally follow in John Nyaphuli’s footsteps, returning to a specimen he discovered nearly two decades ago and finally solve the puzzle he uncovered. At the time, all we had was a beautifully curled embryo, but no preserved eggshell to prove it had died within an egg. Using modern imaging techniques, we were able to answer that question definitively” says Jennifer Botha. “It is also thrilling because this discovery breaks entirely new ground. For over 150 years of South African palaeontology, no fossil had ever been conclusively identified as a therapsid egg. This is the first time we can say, with confidence, that mammal ancestors like Lystrosaurus laid eggs, making it a true milestone in the field”.

  

Egg photographed in the control room of the ESRF in France

Credit

Professor Julien Benoit

3D reconstruction of the skeleton

Credit

Professor Julien Benoit

Journal

PLOS One

DOI

10.1371/journal.pone.0345016 

Article Publication Date

9-Apr-2026

 

Could your housemates be changing your gut bacteria?

University of East Anglia

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Research on a colony Seychelles warblers (pictured) reveals they share more of their gut bacteria with the birds they spend the most time with.

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Credit: Claire Lok Sze Tsui, University of East Anglia

Living with friends may quietly be altering your gut bacteria - according to a new study from the University of East Anglia.

Research on a colony of tiny island birds reveals they share more of their gut bacteria with the birds they spend the most time with.

And the team say the same principle almost certainly applies to humans too.

Previous human studies have hinted at this phenomenon - with spouses and long‑term cohabitees often having more similar gut microbiomes than strangers, even when their diets differ.

But the new bird research provides unusually clear evidence of how social closeness itself - not just shared environment - drives the exchange of gut bacteria.

How the research happened

Researchers studied the Seychelles warbler, a small songbird found on Cousin Island in the Seychelles.

They collected faecal samples from the warblers, which were then used to analyse the birds’ gut microbiomes - the diverse communities of ‘good’ bacteria living in their digestive systems.

Dr Chuen Zhang Lee, from UEA’s School of Biological Sciences, carried out the work as part of his PhD project.

He said: “To uncover how gut bacteria spreads between social partners, we meticulously collected the birds’ poo over several years. We gathered hundreds of samples from birds with known social roles - breeding pairs, helpers and non‑helpers living in the same group, and in different groups.

“This allowed us to compare the gut bacteria of birds that interacted closely at the nest versus those that did not.

“We studied their anaerobic gut bacteria, which thrive without oxygen.

“And it gave us a rare insight into how social bonds can drive the transmission of gut microbes.”

A natural laboratory in the Indian Ocean

Senior researcher Prof David S Richardson, from UEA’s School of Biological Sciences, said: “Cousin Island is small, isolated, and the warblers never leave it. That means every bird on the island can be individually marked and followed throughout its life.

“This offers scientists an exceptional opportunity to study life-long biological processes in the wild.”

All of the island’s warblers are fitted with coloured leg rings, allowing researchers to track their behaviour, health, and genetics over many years. This creates conditions similar to a laboratory population - but in a completely natural setting.

“It gives us the best of both worlds,” said Prof Richardson. “We can study animals living natural lives, with natural diets and gut bacteria, while still being able to collect detailed data from known individuals.”

Sharing gut microbiota with friends

“We found that the more social you are with another individual, the more you share similar anaerobic gut bacteria,” said Dr Lee.

“Birds who spent a lot of time together at the nest – breeding couples and their devoted helpers – shared a lot of this type of gut bacteria, which can only spread through direct, close contact.

“These anaerobic microbes can’t survive in the open air, so they don’t drift around in the environment. Instead, they move between individuals through intimate interactions and shared nests.”

How home life shapes our microbiomes

The team say that the findings shine a spotlight on what may be happening in human homes.

“Whether you’re living with a partner, housemate, or family, your daily interactions - from hugging, kissing and sharing food prep spaces - may encourage the exchange of gut microbes,” said Dr Lee.

“Anaerobic bacteria are some of the most important for digestion, immunity and overall health.

“Once inside the gut, they thrive in oxygen‑free conditions and often form stable, long‑term colonies.

“That means the people you live with might subtly shape the microscopic ecosystem inside you.

“Translated into human terms, this means that cosy nights in, shared washing‑up duties, and even sitting close on the sofa may bring your microbiomes quietly closer together.

“Sharing beneficial anaerobic bacteria could strengthen immunity and improve digestive health across a household,” he added.

This research was led by UEA in collaboration with Norwich Research Park colleagues at the Centre for Microbial Interactions, the Quadram Institute and the Earlham Institute, as well as the University of Sheffield, the University of Groningen (The Netherlands) and Nature Seychelles.

‘Social structure and interactions differentially shape aerotolerant and anaerobic gut microbiomes in a cooperative breeding species’ is published in the journal Molecular Ecology.

ENDS

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Journal

Molecular Ecology

Method of Research

Observational study

Subject of Research

Animals

Article Title

‘Social structure and interactions differentially shape aerotolerant and anaerobic gut microbiomes in a cooperative breeding species’

Article Publication Date

10-Apr-2026

 

Seabirds reveal global mercury distribution in oceans

The analysis was based on blood samples from over 11,000 seabirds, the first biologically derived estimate of oceanic mercury distribution.

Nagoya University

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This study provides the drivers of variation in mercury concentrations in seabirds and, further, the first biologically based estimate of oceanic mercury distribution, analyzing blood mercury levels in more than 11,215 seabirds from 108 species, including 659 newly collected samples and over 10,556 from prior research. (THg: total mercury)

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Credit: Jumpei Okado (modified from Okado et al. 2026, licensed under CC BY 4.0)

Mercury released into the oceans affects marine environments worldwide. Traditionally, its distribution and quantity have been estimated using marine biogeochemical simulation models.

A recent international study led by Japanese researchers analyzed blood mercury concentrations in more than 11,215 seabirds from 108 species, of which 659 were newly collected samples and over 10,556 were from previous studies. This is the first biologically based estimate of oceanic mercury distribution.

The study found that mercury levels in seabirds vary according to prey trophic level, bird body weight, and foraging depth. The findings were published in Science of the Total Environment.

Mercury emissions into the ocean have risen since the Industrial Revolution, primarily due to increased atmospheric mercury from coal combustion. Mercury travels long distances by wind and enters the ocean through rainfall.

In the ocean, some mercury becomes highly toxic and bioaccumulates in the food chain, ultimately concentrating in the tissues of seabirds that consume fish and zooplankton.

Professor Akiko Shoji and Researcher Jumpei Okado of Nagoya University Graduate School of Environmental Studies, along with Senior Researcher Bungo Nishizawa of the Japan Fisheries Research and Education Agency, led an international study with 12 institutions from four countries.

Why were seabird blood samples used?

Blood samples from seabirds are efficiently collected when they come ashore for breeding. Mercury concentrations in adult birds' blood at breeding sites reflect their dietary mercury intake from specific ocean areas within the two months prior to sampling.

This method enables a more accurate correlation of mercury levels with specific times and locations than other sample types. Additionally, blood collection causes minimal harm to the birds.

Analysis of seabird blood data

Between 2017 and 2024, researchers collected blood samples from 659 individuals representing 10 seabird species at breeding sites in Japan, Alaska, and New Zealand. They dried and homogenized the samples, then measured total mercury concentrations using atomic absorption spectrometry. Results were standardized to total mercury per gram of dry weight in whole blood for comparison.

Researchers also conducted a systematic review of 106 publications from 1980 to 2025, with over 80% published after 2010, and analyzed data on more than 10,556 adults representing 105 seabird species.

In total, the team analyzed blood mercury concentrations in over 11,215 individuals from 108 seabird species worldwide, covering diverse diets and geographic regions.

The analysis found that seabirds at higher trophic levels, with larger body mass, and those feeding on prey from depths between 200 and 1,000 meters have higher mercury levels.

Statistical analysis showed distinct regional patterns in oceanic mercury contamination. Mercury levels were higher in the North Atlantic, North Pacific, South Pacific below 40 degrees south, and in areas with low productivity, as indicated by reduced chlorophyll a levels. In contrast, mercury levels were much lower in the South Atlantic and Southern Oceans.

The study also found that albatrosses and shearwaters are more exposed to mercury than other seabird species.

Significance and future perspectives

The researchers found that predictions from the seabird-based model and the marine biogeochemical simulation models were only weakly correlated.

"The seabird model is based on empirical measurements from organisms and is therefore considered more reliable than values from marine simulation models," said Shoji. "Seabirds live in diverse environments, from coastal and tropical zones to polar regions. Their varied feeding patterns make them effective indicators of global ocean health."  

This approach offers a promising method to monitor and verify the effectiveness of international mercury emission regulations, such as the Minamata Convention, and to support stronger global efforts to reduce mercury contamination in marine ecosystems.

 

Funding information:

This study was supported by the Japan Society for the Promotion of Science (Grants-in-Aid for Scientific Research awarded to AS: 23KK0116, 22K21355, and 19KK0159), Japan Science and Technology Agency (EXPLORATORY RESEARCH GRANT awarded to AS: JPMJFR241E), and Japan Polar Research Association (2022 and 2023 awarded to CN). Sample collection in Aotearoa New Zealand was supported by the Conservation Services Programme of the Department of Conservation (POP2022–08, POP20220–7, and POP2022–10), the National Geographic Society (WW-249C-17), the Mohamed Bin Zayed Species Conservation Fund (Project 192520234), and Birds New Zealand (Birds NZ Research fund 2017, 2019).

 

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Journal

Science of The Total Environment

DOI

10.1016/j.scitotenv.2025.181317 

Article Title

Global drivers of variation in blood mercury of seabirds revealed by a meta-analysis