Changes to El Niño occurrence causing widespread tropical insect and spider declines

Griffith University

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Tropical forest arthropods and the functions that they provide may be vulnerable to intensified El Niño events under climate change.

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Credit: Marco Chan

Arthropods, including insects and spiders, make up the vast majority of animal species on the planet.

Despite their small size they are irreplaceable contributors to the health of natural habitats, as well as vital food sources for birds and other larger animals.

But, arthropods may be declining globally. There is some evidence to support reduced numbers of species in temperate regions of the Northen Hemisphere. In the tropics, however, evidence for arthropod declines has so far been limited.

A recent international collaboration of scientists has attempted to find this missing evidence, with the findings published in Nature.

The team, including Professors Roger Kitching and Nigel Stork from Griffith University’s School of the Environment and Science, conducted a whole-of-tropics analysis on tropical forest insects and their relatives and the ecological roles that they perform.

Combining information from over 80 previous studies in tropical forest sites that have never been commercially altered by humans, the team found significant biodiversity loss in multiple types of arthropod, including butterflies, beetles and spiders.

The biodiversity loss matched drops in the amount of live leaf material consumed by arthropods over time, and substantial instability in the amount of dead leaves decomposed by arthropods.

“To find such large declines over many studies is really bad news,” said Dr Adam Sharp, first author and data analyst from Hong Kong University.

“Our results suggest strongly that the immense biodiversity of tropical forest arthropods is immediately threatened.

"Since all of the data we used comes from forest considered ‘untouched’, even the deepest and darkest tropical forests are likely to be heavily impacted.”

The team link climate change to the declines in arthropods and their respective ecological roles. The tropics experience natural but irregular year-to-year variation in climate, driven by an atmospheric phenomenon called the El Niño Southern Oscillation – ENSO. Long-term changes to the ENSO cycle, caused by climate change, are likely behind the observed arthropod declines.

Arthropods can be highly sensitive to ENSO, with different arthropod types coming and going during the opposing El Niño and La Niña stages of the cycle.

While there is considerable difference in effect across the tropics, El Niño conditions are often hot and dry while La Niña conditions are often cooler and wetter.

They should usually strike a balance such that no arthropods ever disappear completely - but the El Niño part of the ENSO cycle is becoming more frequent and more intense due to climate change.

“We believe that changes to El Niño occurrence are causing widespread arthropod declines,” said corresponding author Dr Mike Boyle.

“In these tropical forests that haven’t otherwise been physically modified by humans we can rule out habitat loss, pesticides, pollution and various other threats. In these places El Niño seems to be the prime suspect.”

Indeed, the team found the largest declines in arthropods occurred in those that favour La Niña conditions. If El Niño is becoming detrimental due to climate change, then its occurrence is sure to further chip away at arthropod biodiversity into the future.

“Arthropods are essential components of functioning ecosystems, carrying out vital processes including decomposition, herbivory and pollination,” said University of Hong Kong Associate Professor Louise Ashton.

“We must better understand how nature is shifting and what is happening to arthropods and their ecosystem processes in response to environmental change.

Co-author Professor Roger Kitching from Griffith University said: “The crucial message for Australia is the need to monitor the biodiversity in our rainforests – revisiting previous surveys is the key.”

The international team continue their research at forest sites across Hong Kong and Mainland China, Australia and Malaysia.

The study ‘Stronger El Niños reduce tropical forest arthropod diversity and function’ has been published in Nature.

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Journal

Nature

DOI

10.1038/s41586-025-09351-x 

POLLINATORS!

Decline of seed-dispersing animals hinders fight against climate change

International team of researchers issues global warning about the need to include frugivores in conservation, forest restoration, and climate change mitigation strategies.

Fundação de Amparo à Pesquisa do Estado de São Paulo

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The seed of the fruit passes through the digestive tract of the dispersing animal, where it undergoes treatment that prepares it to germinate when deposited 

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Credit: Mauro Galetti/CBioClima

 

Most trees in the Amazon (90%), the Atlantic Forest (90%), or the Cerrado, the Brazilian savannah-like biome (60%), depend on animals to disperse their seeds, ensure their reproduction, and keep the forest standing. Birds, mammals, fish, and even a species of amphibian play a crucial role in forest diversity around the world. However, this process has been disintegrating as populations of seed-dispersing animals have declined dramatically.

The loss of frugivorous animals (whose diet consists mainly of fruit) has another effect: it alters the composition of forests, weakening their ability to absorb carbon dioxide and thus reducing their role in combating climate change.

Yet, major global efforts to protect and restore ecosystems continue to underestimate seed-dispersing animals in biodiversity conservation and forest restoration strategies.

“There’s a lot of talk today about carbon credits and forest restoration, but who ‘plants’ the carbon? It’s the toucan, the agouti, the tapir, the jacutinga. To have a copaiba tree, for example, the forest needs toucans and monkeys to disperse its seeds. Therefore, we need to include frugivorous animals in the restoration equation, as there’s already enough science to quantify how much forest carbon is planted by animals,” says Mauro Galetti, one of the directors of the Center for Research on Biodiversity Dynamics and Climate Change (CBioClima), a FAPESP Research, Innovation, and Dissemination Center (RIDC) based at the Institute of Biosciences of São Paulo State University (IB-UNESP) in Rio Claro, Brazil.

Galetti and researchers from the United States, Switzerland, Panama, Germany, Spain, and Portugal published an article in Nature Reviews Biodiversity warning about the consequences of losing seed dispersers in a changing climate. According to the researchers, the role of frugivorous animals in maintaining plant biodiversity is so central that efforts to restore and protect ecosystems are at risk of failing to meet their goals if the decline of seed dispersers is not mitigated.

A recent study published in the journal Science by some of the researchers who signed the alert showed that the worldwide loss of birds and mammals results in a 60% reduction in seed dispersal. “We’ve made great strides in addressing these problems of seed disperser loss, and although Brazil is the country with the most scientific studies on seed dispersal, we need to delve deeper into the problem and understand, for example, which plants and ecosystems are most vulnerable to this loss. In addition, of course, we need to identify which strategies best restore seed dispersal,” says the researcher.

Unknown heroes

When a dispersing animal eats a fruit, it becomes “contaminated” by the seed that passes through the digestive tract. The seed receives chemical treatment from gastric juices or mechanical treatment – in the case of birds, for example, the gizzard crushes the seed – which allows water to enter the seed, leaving it ready to germinate wherever the animal later deposits it when defecating.

“Therefore, seeds consumed by animals will germinate more, faster, and will establish themselves in safer places to grow. And if there’s no animal to ‘bruise’ the seed and take it away from the mother plant, it won’t germinate, and even if it germinates near the mother plant, it’ll probably die because there’ll be competition between them,” says Galetti.

However, it is important to note that there is no standard. This interaction is different in every place in the world and for every species of tree and vertebrate animal. “The Brazil nut, for example, has only one disperser: the agouti. If the agouti becomes extinct locally, the Brazil nut’s seed dispersal service will succumb. We therefore depend on a fundamental ecological service provided by the agouti,” says Galetti.

While birds, bats, monkeys, and tapirs are the main seed dispersers in the Atlantic Forest, fish play a crucial role in the Amazon and Pantanal. “Pacu and tambaqui fish, for example, travel long distances and eat large quantities of fruit, which makes them super dispersers of different species in riparian forests,” says the researcher.

Ecosystem services

Like bees and other pollinators, frugivorous animals play a crucial role in plant reproduction. However, despite being threatened by similar factors, such as land use changes and direct exploitation, the two groups respond differently to these impacts. Pollinators are more affected by pesticides, while seed dispersers are more affected by habitat loss and hunting.

Another difference is that the decline of pollinators has received more public and political attention because their absence directly affects food production. The impacts of seed disperser loss, on the other hand, are more difficult to measure and influence biodiversity and carbon storage over time.

“Both are important and should be taken into account in restoration and conservation projects. However, the decline of pollinators is more easily measured in the short term, generating immediate economic impacts such as loss of crop productivity, while the effects of seed disperser loss occur slowly and broadly, compromising the functionality and resilience of ecosystems,” Galetti explained to Agência FAPESP.

The scientist says that the economic costs of the decline of seed dispersers – such as the loss of carbon storage, the reduced supply of forest products, and the decline in natural resilience to extreme environmental events – have not yet been quantified globally. “Restoration isn’t just about planting trees; you have to consider who will maintain the future of that forest, which are the dispersing animals. A few years ago, it was believed that by planting the forest, these animals would come to it. But that’s not how it works. It’s much more complex to have a restored forest functioning,” he says.

In the article, the researchers highlight that new syntheses and data models are capturing large-scale functional changes and helping to reveal long-term impacts, such as impaired recovery from forest fires and degraded animal habitats. “Addressing the decline of seed dispersers is critical to preserving animal biodiversity, ensuring forest connectivity, and balancing plant communities,” says Galetti.

About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe. 

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Journal

Nature Reviews Biodiversity

DOI

10.1038/s44358-025-00053-w 

Article Title

Drivers and impacts of global seed disperser decline

 

Heroes, victims – and rarely collaborators

International study reveals how people across Europe reinterpret their nation's role during the Nazi era

Johannes Gutenberg Universitaet Mainz

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This chart illustrates how people in eight European countries recall their nation's role during World War II. In most cases, citizens are seen as victims or reluctant collaborators. Voluntary collaboration is rarely acknowledged.

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Credit: ill./©: Fiona Kazarovytska

Whether in Belgium, Poland, or Ukraine, when asked about their nation's role under Nazi occupation, many Europeans today primarily see their own population as victims – or as heroes. This is the key finding of a cross-national study led by Dr. Fiona Kazarovytska from the Department of Social and Legal Psychology at Johannes Gutenberg University Mainz (JGU), Germany. Together with Professor Roland Imhoff from JGU and Professor Gilad Hirschberger from Reichman University, Israel, she published the results in the journal Political Psychology. 

The researchers conducted an online survey with 5,474 participants from eight European countries: Austria, Belgium, France, Hungary, Lithuania, the Netherlands, Poland, and Ukraine. Designed to be representative in terms of age and gender, the sample offered insights into how people today represent the role of their own population under Nazi occupation. Participants were asked to rate their level of agreement – on a scale from 1 to 7 – with statements such as "Most of the people in my country actively fought against the Nazis" and "The population mistreated the Jews because they faced death if they refused."

A shared pattern of memory

"Despite historical differences, we see a strikingly similar picture across all countries," said Dr. Fiona Kazarovytska. "People tend to view their own population as 'victim-heroes' – individuals who suffered under Nazi rule while simultaneously resisting it with courage." The belief that collaboration happened out of fear or coercion is also widespread.

However, historical records clearly show that governments or segments of the population in many countries actively cooperated with the Nazi occupiers – whether by providing bureaucratic support for deportations, enacting antisemitic legislation, or directly participating in acts of violence. In today's collective memory, by contrast, voluntary and ideologically driven collaboration plays a far smaller role than narratives of victimhood and resistance.

Psychological mechanisms shape collective memory

This is the first study to systematically and empirically examine how people in eight European countries morally evaluate their nation's historical role under Nazi occupation. By focusing on lay people's perceptions rather than state narratives or official memorial culture, it offers novel insight into the psychological mechanisms that shape collective remembrance. Central to this is how individuals morally position their nation and the role of national identity in historical interpretation.

Similar psychological patterns, such as the tendency to reduce moral discomfort by emphasizing coercion or resistance, are well-documented in research on the German population. This new study shows that such morally absolving narratives are also widespread in other European societies.

Recasting the past to protect national identity

Why do so many people present their nation's past in a more positive light than facts support? "It's a psychological coping strategy to protect national identity," explained Kazarovytska. Confronting morally troubling aspects of one's own history can be deeply unsettling. "Admitting guilt or complicity is hard to reconcile with a positive sense of self." As a result, many turn to narratives that downplay moral ambiguity and recast the past in more positive terms.

The findings of the study shed new light on how national memory cultures are shaped – not only by historical facts, but also by deep-seated psychological needs. They reveal how powerfully the desire for moral integrity shapes collective remembrance – even when it contradicts historical records.

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Journal

Political Psychology

DOI

10.1111/pops.13037 

Article Title

Beyond victimhood and perpetration: Reconstruction of the ingroup's historical role in eight Eastern and Western European countries under Nazi occupation

This smarter sound shield blocks more noise—without blocking air

Boston University researchers unveil a new ultra-open metamaterial that silences a broader range of noise while preserving ventilation

Boston University

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Rectangular and cylindrical PGUOM structures operate on the same underlying mechanism, offering comparable broadband silencing performance. Both geometries maintain high airflow, underscoring the metamaterial’s versatility across diverse application scenarios. The samples shown were 3D-printed using a commercial printer.

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Credit: Photo courtesy of Zhiwei Yang and Xin Zhang.

A new breakthrough from the Zhang Lab at Boston University is making waves in the world of sound control. Led by Professor Xin Zhang (ME, ECE, BME, MSE), the team has published a new paper in Scientific Reports titled “Phase gradient ultra open metamaterials for broadband acoustic silencing.” The article marks a major advance in their long-running Acoustic Metamaterial Silencer project.

The Zhang lab is renowned in the fields of metamaterials and microsystems for its continual advancement of real-world applications. Back in 2019, their research on an Acoustic Metamaterial Silencer—or “sound shield”—aimed to “significantly block sound while maintaining airflow, based on Fano resonance effects,” in the lab’s words. At the time, applications focused on fans, propellers, and HVAC systems, targeting the reduction of narrowband noise while preserving air passage. 

The Zhang lab has since extended its work to explore a broader range of acoustic silencing strategies—including multi-band, broadband, and tunable approaches—making the technology viable in new environments such as factories, offices, and public spaces, where diverse and unpredictable sound frequencies are common and airflow remains essential.

Their latest advance centers on broadband silencing. While this broader control came with a modest trade-off in peak silencing performance—a common challenge when shifting from narrowband to broadband suppression—it unlocked powerful new possibilities. The breakthrough was made possible through the use of phase-gradient metamaterials, giving rise to the Phase Gradient Ultra-Open Metamaterial (PGUOM).

“PGUOM takes a smarter approach—more like noise-canceling headphones—effectively silencing a broadband of unwanted sounds,” says Zhang. “It remains highly effective even as the noise shifts in pitch or volume, making it far more practical in dynamic settings like open offices, ventilation systems, or transportation hubs, where sound sources are unpredictable and span a wide range of frequencies.”

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Journal

Scientific Reports

DOI

10.1038/s41598-025-04885-6 

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

Phase gradient ultra open metamaterials for broadband acoustic silencing

Article Publication Date

1-Jul-2025

COI Statement

Provisional patent is filed based on the findings of this paper, detailed information is provided below. Provisional Patent Name: PHASED ARRAY ULTRA OPEN METAMATERIALS FOR BROADBAND ACOUSTIC SILENCING. Inventors: Xin Zhang, Zhiwei Yang, Ao Chen, Stephan Anderson; U.S. Provisional Application No.: 63/549,846; BU Ref.: BU-2024-010; BL Ref. No.: BOS-0072PR (56136.03184); File date: 02/05/2024. A PCT Patent Application has also been submitted claiming priority from this provisional patent, Title: PHASED ARRAY ULTRA OPEN METAMATERIALS FOR BROADBAND ACOUSTIC SILENCING. Inventors: Xin Zhang, Zhiwei Yang, Ao Chen, Stephan Anderson; PCT Patent Application No. PCT/US2025/014569; BU Ref.: BU-2024-010; CM Ref. No.: 264003-0072PCT (BOS-0072PCT); filed date: February 5, 2025. All the other authors have no competing interest.

Neighbors matter: Community cohesion boosts disaster resilience, Texas A&M study finds

Research on 2015 floods reveals that strong neighborhood bonds enhance recovery after catastrophe, offering key insights for public health and emergency planners.

Texas A&M University

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A study from the Texas A&M University School of Public Health sheds new light on the relationship between community cohesion prior to a natural disaster and resilience after one, with possible policy applications for public health and emergency preparedness practitioners.

“Recent events have reminded us that resilience isn’t just about bricks and budgets,” said community health expert Garett T. Sansom, who led the study. “In part, it’s also about bonds between neighbors.”

Until now, he added, little has been known about the mechanisms by which cohesion influences recovery. To explore this issue — as well as how the relationship between cohesiveness and resilience varies by context — the researchers analyzed the aftermath of the 2015 Memorial Day Flood in Hays County, Texas, part of the Austin-Round Rock metropolitan area, and, at the time, home to about 158,000 residents.

Their research was funded by the Texas A&M Superfund Research Center and the National Science Foundation and published in Disaster Medicine and Public Health Preparedness.

“Beginning that May 23, the Blanco and San Marcos rivers in Central Texas experienced historic flash flooding, causing at least a dozen deaths and destroying more than 2,000 homes in Hays County alone,” Sansom said.

The disaster launched significant local volunteer efforts, neighbor-to-neighbor assistance and grassroots recovery efforts that Sansom said indicated cohesion-driven resilience.

For their study, conducted in the summer and fall of 2022, the researchers — along with students from the School of Public Health’s EpiAssist program and community leaders from the Blanco River Academy — asked 128 county residents about their experiences with the flooding, including receipt of hazard warnings, housing damage, length of community residency and perceived recovery progress.

The survey also asked respondents for demographic information and opinions about the sense of community and empowerment they sensed in their neighborhoods.

A statistical analysis found a significant positive association between community cohesion and perceived resilience, while variables such as age, gender and socioeconomic status showed no significant relationships.

“These findings — like those of similar studies — underscore the importance of strong social ties in disaster recovery and resilience,” Sansom said.

In addition, he said they suggest that explicit strategies for building community trust and increasing volunteerism rates and civic engagement should be added to emergency preparedness programs.

“Communities that build strong social ties and mutual trust tend to recover much more quickly and smoothly following a catastrophe — but only if other resources and structural support are also present,” he said. “In other words, our study found that social cohesion is important to disaster resilience but does not guarantee it.”

Others on the research team were Lindsay Sansom and graduate students Lyssa Losa, Jacquita N.Johnson and Ruby Hernandez from the Department of Environmental and Occupational Health, as well as faculty member Benika Dixon and graduate student TyKeara Mims from the Department of Epidemiology and Biostatistics.

By Ann Kellett, Texas A&M University School of Public Health

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Journal

Disaster Medicine and Public Health Preparedness

DOI

10.1017/dmp.2025.10119 

Method of Research

Survey

Subject of Research

People

Article Title

Cohesive Cities and Resilient Cities: Are they the Same?