Natural clean-up: Bacteria can remove plastic pollution from lakes

Peer-Reviewed Publication

UNIVERSITY OF CAMBRIDGE

 

IMAGE: A FRESHWATER LAKE IN NORWAY, ONE OF 29 EUROPEAN LAKES THAT WERE PART OF THE STUDY. view more 

CREDIT: SAMUEL WOODMAN

A study of 29 European lakes has found that some naturally-occurring lake bacteria grow faster and more efficiently on the remains of plastic bags than on natural matter like leaves and twigs.

The bacteria break down the carbon compounds in plastic to use as food for their growth.

The scientists say that enriching waters with particular species of bacteria could be a natural way to remove plastic pollution from the environment.

The effect is pronounced: the rate of bacterial growth more than doubled when plastic pollution raised the overall carbon level in lake water by just 4%.

The results suggest that the plastic pollution in lakes is ‘priming’ the bacteria for rapid growth –  the bacteria are not only breaking down the plastic but are then more able to break down other natural carbon compounds in the lake.

Lake bacteria were found to favour plastic-derived carbon compounds over natural ones. The researchers think this is because the carbon compounds from plastics are easier for the bacteria to break down and use as food.

The scientists caution that this does not condone ongoing plastic pollution. Some of the compounds within plastics can have toxic effects on the environment, particularly at high concentrations.

The findings are published today in the journal Nature Communications.

“It’s almost like the plastic pollution is getting the bacteria’s appetite going. The bacteria use the plastic as food first, because it’s easy to break down, and then they’re more able to break down some of the more difficult food – the natural organic matter in the lake,” said Dr Andrew Tanentzap in the University of Cambridge’s Department of Plant Sciences, senior author of the paper.

He added: “This suggests that plastic pollution is stimulating the whole food web in lakes, because more bacteria means more food for the bigger organisms like ducks and fish.”

The effect varied depending on the diversity of bacterial species present in the lake water – lakes with more different species were better at breaking down plastic pollution.

CAPTION

A freshwater lake in Norway, one of the 29 European lakes analysed as part of the study.

CREDIT

Andrew Tanentzap

A study published by the authors last year found that European lakes are potential hotspots of microplastic pollution.

When plastics break down they release simple carbon compounds. The researchers found that these are chemically distinct to the carbon compounds released as organic matter like leaves and twigs break down.

The carbon compounds from plastics were shown to be derived from additives unique to plastic products, including adhesives and softeners.

The new study also found that bacteria removed more plastic pollution in lakes that had fewer unique natural carbon compounds. This is because the bacteria in the lake water had fewer other food sources.

The results will help to prioritise lakes where pollution control is most urgent. If a lake has a lot of plastic pollution, but low bacterial diversity and a lot of different natural organic compounds, then its ecosystem will be more vulnerable to damage.

“Unfortunately, plastics will pollute our environment for decades. On the positive side, our study helps to identify microbes that could be harnessed to help break down plastic waste and better manage environmental pollution," said Professor David Aldridge in the University of Cambridge’s Department of Zoology, who was involved in the study.

The study involved sampling 29 lakes across Scandinavia between August and September 2019. To assess a range of conditions, these lakes differed in latitude, depth, area, average surface temperature and diversity of dissolved carbon-based molecules.

The scientists cut up plastic bags from four major UK shopping chains, and shook these in water until their carbon compounds were released.

At each lake, glass bottles were filled with lake water. A small amount of the ‘plastic water’ was added to half of these, to represent the amount of carbon leached from plastics into the environment, and the same amount of distilled water was added to the others. After 72 hours in the dark, bacterial activity was measured in each of the bottles.

The study measured bacterial growth - by increase in mass, and the efficiency of bacterial growth - by the amount of carbon-dioxide released in the process of growing.

In the water with plastic-derived carbon compounds, the bacteria had doubled in mass very efficiently. Around 50% of this carbon was incorporated into the bacteria in 72 hours.

"Our study shows that when carrier bags enter lakes and rivers they can have dramatic and unexpected impacts on the entire ecosystem. Hopefully our results will encourage people to be even more careful about how they dispose of plastic waste," said Eleanor Sheridan in the University of Cambridge’s Department of Plant Sciences, first author of the study who undertook the work as part of a final-year undergraduate project.

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JOURNAL

Nature Communications

DOI

10.1038/s41467-022-31691-9 

METHOD OF RESEARCH

Observational study

ARTICLE TITLE

Plastic pollution fosters more microbial growth in lakes than natural organic matter

ARTICLE PUBLICATION DATE

26-Jul-2022

Space study offers clearest understanding yet of the life cycle of supermassive black holes

Research uses X-ray telescopes and a new data analysis technique to describe space objects

Peer-Reviewed Publication

DARTMOUTH COLLEGE

 

IMAGE: THE DOUGHNUT-SHAPED RING SURROUNDING MANY SUPERMASSIVE BLACK HOLES TELLS RESEARCHERS ABOUT HOW FAST THE SPACE OBJECT IS FEEDING AND CAN CHANGE HOW THE BLACK HOLE IS VIEWED FROM EARTH. view more 

CREDIT: ESA/NASA, THE AVO PROJECT AND PAOLO PADOVANI

Black holes with varying light signatures but that were thought to be the same objects being viewed from different angles are actually in different stages of the life cycle, according to a study led by Dartmouth researchers.

The research on black holes known as “active galactic nuclei,” or AGNs, says that it definitively shows the need to revise the widely used “unified model of AGN” that characterizes supermassive black holes as all having the same properties.

The study, published in The Astrophysical Journal, provides answers to a nagging space mystery and should allow researchers to create more precise models about the evolution of the universe and how black holes develop.

“These objects have mystified researchers for over a half-century,” said Tonima Tasnim Ananna, a postdoctoral research associate at Dartmouth and lead author of the paper. “Over time, we’ve made many assumptions about the physics of these objects. Now we know that the properties of obscured black holes are significantly different from the properties of AGNs that are not as heavily hidden.”

Supermassive black holes are believed to reside at the center of nearly all large galaxies, including the Milky Way. The objects devour galactic gas, dust and stars, and they can become heavier than small galaxies.

For decades, researchers have been interested in the light signatures of active galactic nuclei, a type of supermassive black hole that is “accreting,” or in a rapid growth stage.

Beginning in the late 1980s, astronomers realized that light signatures coming from space ranging from radio wavelengths to X-rays could be attributed to AGNs. It was assumed that the objects usually had a doughnut-shaped ring—or “torus”—of gas and dust around them. The different brightness and colors associated with the objects were thought to be the result of the angle from which they were being observed and how much of the torus was obscuring the view.

From this, the unified theory of AGNs became the prevalent understanding. The theory guides that if a black hole is being viewed through its torus, it should appear faint. If it is being viewed from below or above the ring, it should appear bright. According to the current study, however, the past research relied too heavily on data from the less obscured objects and skewed research results.

The new study focuses on how quickly black holes are feeding on space matter, or their accretion rates. The research found that the accretion rate does not depend upon the mass of a black hole, it varies significantly depending on how obscured it is by the gas and dust ring.

“This provides support for the idea that the torus structures around black holes are not all the same,” said Ryan Hickox, professor of physics and astronomy and a co-author of the study. “There is a relationship between the structure and how it is growing.”

The result shows that the amount of dust and gas surrounding an AGN is directly related to how much it is feeding, confirming that there are differences beyond orientation between different populations of AGNs. When a black hole is accreting at a high rate, the energy blows away dust and gas. As a result, it is more likely to be unobscured and appear brighter. Conversely, a less active AGN is surrounded by a denser torus and appears fainter.

"In the past, it was uncertain how the obscured AGN population varied from their more easily observable, unobscured counterparts,” said Ananna. “This new research definitively shows a fundamental difference between the two populations that goes beyond viewing angle.”

The study stems from a decade-long analysis of nearby AGNs detected by Swift-BAT, a high-energy NASA X-ray telescope. The telescope allows researchers to scan the local universe to detect obscured and unobscured AGNs.

The research is the result of an international scientific collaboration—the BAT AGN Spectroscopic Survey (BASS)—that has been working over a decade to collect and analyze optical/infrared spectroscopy for AGN observed by Swift BAT.

“We have never had such a large sample of X-ray detected obscured local AGN before,” said Ananna. “This is a big win for high-energy X-ray telescopes.”

The paper builds on previous research from the research team analyzing AGNs. For the study, Ananna developed a computational technique to assess the effect of obscuring matter on observed properties of black holes, and analyzed data collected by the wider research team using this technique.

According to the paper, by knowing a black hole’s mass and how fast it is feeding, researchers can determine when most supermassive black holes underwent most of their growth, thus providing valuable information about the evolution of black holes and the universe.

“One of the biggest questions in our field is where do supermassive black holes come from,” said Hickox. “This research provides a critical piece that can help us answer that question and I expect it to become a touchstone reference for this research discipline.”

Future research could include focusing on wavelengths that allow the team to search beyond the local universe. In the nearer term, the team would like to understand what triggers AGNs to go into high accretion mode, and how long it takes rapidly accreting AGNs to transition from heavily obscured to unobscured.

Researchers contributing to the study include Benny Trakhtenbrot, Tel Aviv University; Claudia Megan Urry, Yale University; and Mike Koss of Eureka Scientific.

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JOURNAL

The Astrophysical Journal

DOI

10.3847/1538-4365/ac5b64 

ARTICLE TITLE

Distribution Functions of DR2 Eddington-ratios, Black Hole Masses, and X-ray Luminosities

ARTICLE PUBLICATION DATE

15-Jul-2022

Pre-teen children believe ‘brilliance’ is a male trait, and this stereotype increases in strength up to the age of twelve

Peer-Reviewed Publication

NANYANG TECHNOLOGICAL UNIVERSITY

 

IMAGE: FIGURE 1. SAMPLE TEST TRIALS FROM THE GENDER-BRILLIANCE IAT. DURING HALF OF THE TRIALS, PARTICIPANTS HAD TO PRESS A KEY TO CATEGORISE THE MALE PHOTOGRAPHS WITH THE GENIUS WORDS. THIS PROCESS WAS REPEATED IN THE SECOND HALF OF THE TRIALS WITH FEMALE PHOTOGRAPHS AND GENIUS WORDS. PARTICIPANTS WITH AN IMPLICIT “BRILLIANCE = MEN” ASSOCIATION WILL REACT FASTER TO TRIALS INVOLVING PICTURES OF MEN THAN PICTURES INVOLVING WOMEN. THE PHOTOGRAPHS HAVE BEEN PROCESSED TO PROTECT THE PRIVACY OF THE VOLUNTEERS. view more 

CREDIT: NTU SINGAPORE

Children hold stereotypical views that ‘brilliance’ is a male trait, and this belief strengthens as they grow up to the age of twelve, researchers from Singapore and the United States have reported.

The study led by Nanyang Technological University, Singapore (NTU Singapore) in collaboration with New York University, was published in the scientific journal Child Development in May 2022. It involved 389 Chinese Singaporean parents and 342 of their children aged 8 to 12.

Tests were carried out to measure the extent to which parents and their children associate the notion of brilliance with men, and to probe the relationship between parents and their children’s views.

The study defined brilliance as an exceptional level of intellectual ability and results showed that children are as likely to associate brilliance with men, as their parents are.

This belief was stronger among older children and stronger among those children whose parents held the same view. 

While previous research on gender stereotypes has found the idea that giftedness is a male trait can emerge at around the age of six, it was not known whether and how this stereotype changes over the course of childhood, until now.  

Lead author of the study, Associate Professor Setoh Peipei from NTU Singapore’s School of Social Sciences, said the Singapore-based study is the first to identify that the tendency to associate brilliance with men (also known as the ‘brilliance equals to men’ stereotype) increases in strength through the primary school years, and reaches the level of belief seen in adults by the age of 13.

“Stereotypical views about how boys are smarter than girls can take root in childhood and become a self-fulfilling prophecy,” said Prof Setoh. “For girls, this may lead them to doubt their abilities, thus limiting their ideas about their interests and what they can achieve in life.”

“Our research work shows parents must also be included in policies and school programmes to effectively combat children’s gender stereotypes from a young age,” she added.

For example, as previous studies have found that parents use different explanation styles for daughters and for sons, the research team said programmes to train parents and teachers to be mindful of balancing their behaviour during interactions with children - especially with girls - could be introduced.

The authors say the study offers evidence to support Singapore’s push to close the gender gap in the Science, Technology, Engineering, and Mathematics (STEM) sectors.

While Singapore has the second highest in the world OECD PISA scores in mathematics, science and reading, a recent study by the Promotion of Women in Engineering, Research, and Science (POWERS) programme at NTU Singapore found that women in Singapore are less confident in their math and science abilities compared to men.[1] Women are also more likely than men to perceive gender barriers to STEM career entry and career progress.

How the study was conducted

The researchers used the Implicit Association Test (IAT) – a commonly-used implicit measure of stereotyping – to evaluate parents’ and children’s behaviour. During the test, participants were asked to categorise photographs of men and women, along with two sets of words. One set of ‘genius words’ referred to the notion of brilliance and included words such as “super-smart” and “genius”, while the other set of words referred to creativity (control attribute).  

During the first half of the trials, participants had to press a key to categorise the male photographs with the genius words. This process was repeated in the second half of the trials with female photographs and genius words (See Figure 1). Participants with an implicit association of men being brilliant will react faster to the task of categorising genius words with the male photographs than the same task with female photographs.

Results revealed an average D score (a metric of the strength of the stereotypical ‘intellectual brilliance = men’ association) of 0.16, indicating that Singaporean children associate brilliance with men more than women[2] and that this stereotypical belief increased in strength with age among the child sample and reached stereotype levels comparable to those of adults by age 12. Thereafter, there was little change in their perspective.

In the second part of the study, the researchers investigated scores from parent-child pairs who took the tests separately but at the same time and found that children’s scores were correlated to their parents’ test scores. This finding suggests that during the earlier years of primary school, parents may play a role in their children’s acquisition of the ‘brilliance equals to men’ stereotype.

Further analysis revealed that as the age of the boys that were tested got older, they were less likely to hold the same stereotypical views of males as more brilliant as their parents. However, for girls, their stereotypes remained closely linked to their parents’ stereotypes throughout the primary school years.

Co-author Andrei Cimpian, Professor of Psychology at New York University said, “This study adds to the evidence that the gender imbalances observed in many prestigious careers are not a function of differences between women and men in their inherent aptitudes or interests. Rather, these imbalances are the product of the messages that young people are getting from those around them about what women and men are supposedly – and supposed to be – like. As a society, we have a responsibility to work toward addressing this issue.”

Moving forward, the research team is studying whether this gender stereotype about brilliance may differently impact primary and secondary school girls’ and boys’ outcomes in math - a core STEM subject that is typically believed to require intellectual brilliance to excel in.

The project investigates various math outcomes that can predict children’s future participation in STEM fields, including math achievement, interest, and confidence in doing math. The researchers hope that by unravelling how the gender stereotype about brilliance functions to divert girls’ and boys’ interests and aspirations from an early age, the project will offer valuable insights into designing interventions to curb the circulation of gender stereotypes and ultimately help to close STEM gender gaps in society.

***END***

 

Notes to Editor:

Paper titled “The acquisition of the gender-brilliance stereotype: Age trajectory, relation to parents' stereotypes, and intersections with race/ethnicity” published in Child Development, 30 May 2022
DOI: 10.1111/cdev.13809

[1] “Closing the STEM gender gap in Singapore”, whitepaper by POWERS, published 4 March 2022

[2] A D score above the neutral point of zero indicates that children found the ‘brilliance = men’ association more cognitively fluent, so it was easier for them to pair men with the concept of brilliance than women during the test.

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JOURNAL

Child Development

DOI

10.1111/cdev.13809 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

The acquisition of the gender-brilliance stereotype: Age trajectory, relation to parents' stereotypes, and intersections with race/ethnicity

The world's largest omnivore is a fish

Marine scientists have discovered that whale sharks eat plants, making the iconic fish the world’s largest omnivore.

Peer-Reviewed Publication

AUSTRALIAN INSTITUTE OF MARINE SCIENCE

 

IMAGE: RESEARCHERS DISCOVERED WHALE SHARKS ATE PLANTS AS WELL AS KRILL. view more 

CREDIT: PHOTO BY ANDRE REREKURA, AUSTRALIAN INSTITUTE OF MARINE SCIENCE

Marine scientists have discovered that whale sharks eat plants, making the iconic fish the world’s largest omnivore.

Whale sharks are filter feeders and have long been observed eating krill at Western Australia’s Ningaloo Reef.

But when researchers analysed biopsy samples from whale sharks at the reef, they discovered the animals were actually eating a lot of plant material.

“This causes us to rethink everything we thought we knew about what whale sharks eat,” said Australian Institute of Marine Science fish biologist Dr Mark Meekan. “And, in fact, what they’re doing out in the open ocean.”

The finding makes whale sharks—which have been reported up to 18m long—the world’s largest omnivore.

“On land, all the biggest animals have always been herbivores,” Dr Meekan said.

“In the sea we always thought the animals that have gotten really big, like whales and whale sharks, were feeding one step up the food chain on shrimp-like animals and small fishes.

“Turns out that maybe the system of evolution on land and in the water isn’t that different after all.”

The research was published in the journal Ecology.

CAPTION

Researchers were surprised to discover whale sharks ate seaweed as well as krill at Ningaloo Reef, Western Australia.

CREDIT

Photo by Andre Rerekura, Australian Institute of Marine Science

To find out exactly what the whale sharks were eating, the researchers collected samples of possible food sources at the reef, from tiny plankton to large seaweed.

They then compared the amino acids and fatty acids in the plankton and plant material to those in the whale sharks.

Dr Meekan said the whale shark tissue contained compounds found in Sargassum, a type of brown seaweed common at Ningaloo, which breaks off the reef and floats at the surface.

“We think that over evolutionary time, whale sharks have evolved the ability to digest some of this Sargassum that's going into their guts,” he said.

“So, the vision we have of whale sharks coming to Ningaloo just to feast on these little krill is only half the story. They’re actually out there eating a fair amount of algae too.”

CAPTION

Researchers found whale sharks at Ningaloo Reef in Western Australia were eating seaweed as well as krill.

CREDIT

Photo by Andre Rerekura, Australia Institute of Marine Science

CSIRO Oceans and Atmosphere organic biogeochemist Dr Andy Revill, who analysed the whale shark tissue using compound-specific stable isotope analysis, said the technology allowed scientists to study what animals were using for energy and growth, not just what they were eating.

“Something like a whale shark, which swims through the water with its mouth open, is going to ingest a lot of different things,” he said.

“But you don't know how much of that has been used by the animal and how much just goes straight out the other end.

“Whereas stable isotopes, because they're actually incorporated into the body, are a much better reflection of what the animals are actually utilising to grow.”

Biological oceanographer Dr Patti Virtue, from the University of Tasmania’s Institute for Marine and Antarctic Studies, said she was surprised by the whale shark’s biochemical signature.

“It’s very strange, because in their tissue they don’t have a fatty acid or stable isotope signature of a krill-feeding animal,” she said.

CAPTION

Researchers were surprised to discover whale sharks ate seaweed as well as krill at Ningaloo Reef, Western Australia.

CREDIT

Photo by Andre Rerekura, Australian Institute of Marine Science

The researchers also caught whale shark poo with a net and analysed it.

“The poo did show that they were eating krill,” Dr Virtue said. “But they're not metabolising much of it.”

Download images and vision: https://cloudstor.aarnet.edu.au/plus/s/MjapJuYdTiRKxyi

This AIMS whale shark research project is supported by Santos and INPEX as Joint Venture participants in the Van Gogh Development.

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JOURNAL

Ecology

DOI

10.1002/ecy.3818 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

The World's Largest Omnivore is a Fish

ARTICLE PUBLICATION DATE

19-Jul-2022

COI STATEMENT

This whale shark research project was supported by Santos and INPEX as Joint Venture participants in the Van Gogh Developmen

Extreme heat exposure worsens child malnutrition

Peer-Reviewed Publication

CORNELL UNIVERSITY

ITHACA, N.Y. – Exposure to extreme heat increases both chronic and acute malnutrition among infants and young children in low-income countries – threatening to reverse decades of progress, Cornell University research finds.

Linking survey and geocoded weather data over more than 20 years, a study of more than 32,000 West African children ages 3-36 months found that average heat exposure had increased the prevalence of stunted growth from chronic malnutrition by 12%, and of low weight from acute malnutrition by 29%.

The researchers estimate that if the average global temperature rises 2 degrees Celsius – which scientists warn is likely without significant reductions in carbon emissions – the average effect of heat exposure on stunting would nearly double, erasing gains recorded during the study period (1993 to 2014).

The findings are worrying, the researchers said, because temperatures in West Africa are rising and expected to continue to do so for several decades. And the effects of acute and chronic malnutrition in early childhood, which are linked to higher mortality rates and to lower education and incomes in adulthood, are irreversible.

“We’re talking about children at a very young age that will have changes for the rest of their lives, so this is permanently scarring their potential,” said Ariel Ortiz-Bobea, an associate professor and applied agricultural economist at Cornell. “What we are doing to reduce global poverty is being eroded by our lack of action on climate.”

Ortiz-Bobea is a co-author of “Heat exposure and child nutrition: Evidence from West Africa,” published in the Journal of Environmental Economics and Management, with John Hoddinott, a professor of food and nutrition economics and policy at Cornell.

The paper’s lead author is Sylvia Blom, a Cornell Ph.D. graduate, now a postdoctoral research associate at the University of Notre Dame.

Strategies to reduce child malnutrition, the researchers conclude, will need to consider increased needs for programs during periods of prolonged heat exposure.

Meanwhile, improved incomes, infrastructure and child care practices during the study period helped reduce stunting across the five West African countries by 5.8 percentage points on average.

“While this progress has been welcomed in West Africa and in other low- and middle-income countries, it’s occurring against the backdrop of rising temperatures and an increased likelihood of extreme weather events,” Hoddinott said. “Our work suggests these rising temperatures risk wiping out that progress.”

The researchers acknowledged funding support from the African Development Bank through the Structural Transformation of African Agriculture and Rural Spaces (STAARS) project.

For additional information, see this Cornell Chronicle story.

-30-

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JOURNAL

Journal of Environmental Economics and Management

DOI

10.1016/j.jeem.2022.102698 

ARTICLE TITLE

Heat exposure and child nutrition: Evidence from West Africa

Mass mortality events linked to marine heatwaves could become the new norm in the Mediterranean Sea

This is the main conclusion of a study led by the ICM-CSIC that proves that between 2015 and 2019, these events affected all Mediterranean regions.

Peer-Reviewed Publication

INSTITUT DE CIÈNCIES DEL MAR (ICM-CSIC)

 

IMAGE: MARINE HEATWAVES DRIVE RECURRENT MASS MORTALITIES IN THE MEDITERRANEAN SEA view more 

CREDIT: GARRABOU ET AL 2022

An international team of researchers led by the Institut de Ciències del Mar (ICM-CSIC) has proven that, between 2015 and 2019, the Mediterranean experienced a series of marine heat waves that affected all regions of the basin, which resulted in recurrent mass mortality events throughout the period analyzed. The details are reported in a study recently published in the journal Global Change Biology.

According to the work, that has also involved experts from the Centre d'Estudis Avançat de Blanes (CEAB), the Institut Mediterrani d'Estudis Avançats (IMEDEA), the Instituto Español de Oceanografía (IEO), the Universitat de Barcelona (UB), the Universidad de Alicante (UA), the Universidad de Sevilla (US) and the Museo del Mar de Ceuta, as well as other international centres, populations of some 50 species (including corals, sponges and macroalgae, among others) were affected by these events along thousands of kilometres of Mediterranean coasts, from the Alboran Sea to the Near Eastern coasts.

"Specifically, the impacts of mortalities were observed between the surface and 45 meters’ depth, where the recorded marine heat waves were exceptional, affecting more than 90% of the Mediterranean surface and reaching temperatures of more than 26ºC", explains the ICM-CSIC researcher Joaquim Garrabou, one of the authors of the study.

Key species, the most affected

Some of the most affected species are key to maintaining the functioning and biodiversity of the main coastal habitats. These include Posidonia oceanica meadows or coral assemblages, two of the most emblematic habitats in the Mediterranean.

This is the first study to assess the effects of mass mortalities on a Mediterranean scale over five consecutive years. In total, more than 30 research groups from 11 countries have participated, which has made it possible to note the incidence and severity of mortality in every corner of the basin. In fact, this is the most complete picture yet of the impacts of extreme warming events on marine organisms and ecosystems in the Mediterranean.

"Unfortunately, the results of the work show that the Mediterranean Sea is experiencing an acceleration of ecological impacts associated with climate change, posing an unprecedented threat to the health and functioning of its ecosystems", regret Cristina Linares and Bernat Hereu, from the Faculty of Biology and the Biodiversity Research Institute (IRBio) of the UB.

From the exception to the norm

The climate crisis is severely affecting marine ecosystems around the world and the Mediterranean is no exception. Specifically, the associated marine heat waves are causing massive mortality events in all coastal ecosystems of this basin as a result of their increased frequency, intensity and extent.

"Given this scenario, it is essential to know the relationship between the different biological responses of marine biodiversity and different levels of heat exposure", points out the US professor Free Espinosa. For their part, David Díaz and Emma Cebrián, researchers at the IEO and the CEAB, respectively, explain that “the high variability of observed responses among species and populations at very different spatial and temporal scales has undermined our ability to explore this relationship".

Now, thanks to the temporal and spatial resolution addressed, it has been possible to demonstrate that there is a significant positive relationship between the duration of heat waves and the incidence of mortality events.

"Mass mortality events in the Mediterranean are equivalent to the bleaching events also observed consecutively in the Great Barrier Reef, suggesting that these episodes are already the norm rather than the exception," highlights the UA professor Alfonso Ramos.

For all these reasons, the authors urge to strengthen coordination and cooperation at regional, national and international levels, as has been done in this work, in order to reach more effective management decisions to cope with the ongoing climate emergency.

The research has been carried out thanks to the support of the European projects H2020 MERCES, H2020Futurmares, InterregMED MPA-Engage, and the National Plan HEATMED project (RTI2018-095346-B-485 I00).

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JOURNAL

Global Change Biology

DOI

10.1111/gcb.16301 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Marine heatwaves drive recurrent mass mortalities in the Mediterranean Sea