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.

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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

New study by researchers from Pusan National University explores the prevalence of heatwaves in East Asia

How do heatwaves develop and how will human-induced climate change affect them?

Peer-Reviewed Publication

PUSAN NATIONAL UNIVERSITY

 

IMAGE: CATEGORIZATION AND CHARACTERIZATION OF HEATWAVES IN DAYS TO COME CAN HELP HUMANITY ADEQUATELY PLAN FOR CATASTROPHIC CLIMATIC CONDITIONS, SUGGESTS A NEW STUDY BY PUSAN NATIONAL UNIVERSITY RESEARCHERS. view more 

CREDIT: PUSAN NATIONAL UNIVERSITY

Described as periods of excessively high temperatures, heatwaves have a devastating impact on human life, agriculture, and water resources. Weather and atmospheric conditions can lead to two types of heatwaves: dry heatwaves occur when the skies are clear, exposing the area to large amounts of solar radiation, while moist heatwaves occur when water vapor traps heat due to cloudy, humid conditions. Owing to the effects of global warming, these events have grown more intense and frequent in recent years. With climate simulations predicting heatwaves to be more frequent and intensify with increasing greenhouse gas emissions, it becomes important to map out vulnerable regions so that adequate plans can be made to deal with them in the future.

Now, in a study published in npj climate and atmospheric science, a team of international researchers led by Professor Kyung-Ja Ha from Pusan National University, South Korea, have analyzed the prevalence of the two types of heatwaves in East Asia. Using historical climate data, they determined for the first time how and where these heatwaves form and also predicted the occurrence of heatwaves in the future under different greenhouse gas emission scenarios.

According to their study, dry heatwaves occur mainly in northwestern East Asia, while moist heatwaves are prevalent over southern East Asia. These heatwaves were observed to have intensified in duration and frequency over the past 60 years (1958–2019).  The research team found that these heatwaves tend to be frequent under favorable large-scale atmospheric conditions, which vary for dry and moist heatwaves. “In dry heatwave regions, anticyclonic, that is clockwise circulation, is amplified after the onset of heatwaves under the influence of the convergence of anomalous wave activity flux over northern East Asia. This results in surface warming via adiabatic processes. In contrast, the moist heatwaves are triggered by the locally generated anticyclonic circulation anomalies, and surface warming in these cases is amplified by cloud and water vapor feedback,” explains Prof. Ha.

The researchers then went on to analyze how increases in greenhouse gas emissions would affect heatwaves. The simulations revealed more frequent dry heatwaves and longer-lasting moist heatwaves even when greenhouse gas emissions were kept to a minimum to limit the temperature rise to 1.5°C, suggesting the need for further reductions in greenhouse gas emissions to avoid severe heatwave conditions.

Studying heatwaves by their types is essential as these events form under different conditions and lead to different outcomes. “Increases in dry heatwaves are expected to damage agriculture, while moist heatwaves can be extremely detrimental to the human body,” cautions Prof. Ha. Identifying vulnerable regions can assist governing bodies in developing strategies that will mitigate the impacts of severe heatwaves. This involves planning for increased electricity use in places at risk of experiencing moist heatwaves and managing water supplies in regions susceptible to dry heatwaves.

***

 

Reference

Authors: Kyung-Ja Ha 1,2, Ye-Won Seo 1,3, Ji-Hye Yeo 1,2, Axel Timmermann 1,3, Eui-Seok Chung 4*, Christian L. E. Franzke 1,3, Johnny C. L. Chan 5, Sang-Wook Yeh 6 and Mingfang Ting 7

DOI: https://doi.org/10.1038/s41612-022-00272-4

Affiliations:     

1 Center for Climate Physics, Institute for Basic Science, Busan, South Korea

2 Department of Atmospheric Sciences, Pusan National University, Busan, South Korea

3 Pusan National University, Busan, South Korea

4 Korea Polar Research Institute, South Korea

5 City University of Hong Kong, China

6 Hanyang University, South Korea

7 Columbia University, USA

 

Lab Page: https://ibsclimate.org , http://gmcl.pusan.ac.kr

ORCID ID (Kyung-Ja Ha): https://orcid.org/0000-0003-1753-9304

 

About Pusan National University

Pusan National University, located in Busan, South Korea, was founded in 1946, and is now the no. 1 national university of South Korea in research and educational competency. The multi-campus university also has other smaller campuses in Yangsan, Miryang, and Ami. The university prides itself on the principles of truth, freedom, and service, and has approximately 30,000 students, 1200 professors, and 750 faculty members. The university is composed of 14 colleges (schools) and one independent division, with 103 departments in all.    

Website: https://www.pusan.ac.kr/eng/Main.do

 

About the authors

Prof. Kyung-Ja Ha, an expert in the climatic extreme and monsoon hydrology at Pusan National University. She joined the department of atmospheric sciences as a faculty member in 1994. Her research group has been leading the research on monsoon dynamics, climate physics, and boundary layer physics. She has also been working at the IBS Center for Climate Physics (ICCP) with Prof. Axel Timmermann (director of ICCP) from 2017 as affiliated professor.

She has coauthored this article with co-corresponding authors, Dr. Ye-Won Seo (ICCP) and Dr. Eui-Seok Chung (KOPRI) who are experts in climate physics and dynamics, developing mechanisms for extremes such as heatwaves, droughts, and compound climatic hazards.

ICCP’s Ji-Hye Yeo, Axel Timmermann, Christian Franzke (ICCP), Johnny Chan (City University of Hong Kong), Sang-Wook Yeh (Hanyang University), and Mingfang Ting (Lamont-Doherty Earth Observatory, Columbia University) are also co-authors of this study.

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JOURNAL

npj Climate and Atmospheric Science

DOI

10.1038/s41612-022-00272-4 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Dynamics and characteristics of dry and moist heatwaves over East Asia

Do fish suffer from oxygen starvation?

Peer-Reviewed Publication

RADBOUD UNIVERSITY NIJMEGEN

 

IMAGE: BASED ON THEIR INSIGHTS, THE RESEARCHERS HAVE IDENTIFIED – IN GREAT DETAIL AND WORLDWIDE – WHICH FISH ARE LIKELY TO THRIVE IN WHICH BODIES OF WATER, FROM OCEANS TO SMALL RIVERS. "WE CALCULATED THIS FOR TWO 'HYPOTHETICAL' FISHES, ONE LARGE AND ONE SMALL. SMALL FISH DO WELL IN WARM ENVIRONMENTS, SUCH AS THE TROPICS, AND LARGE FISH DO BETTER IN COLDER REGIONS. WE MAY ALSO BE ABLE TO EXTEND THESE PROJECTIONS IN THE FUTURE TO CALCULATE THE EFFECTS OF ENVIRONMENTAL CHANGE." view more 

CREDIT: RADBOUD UNIVERSITY

Larger fishes are more likely to experience oxygen deficiency in warming water than smaller species. The same applies to fish with large cells, note researchers at Radboud University in their latest study. In addition, marine fishes are less tolerant of oxygen-depleted water than freshwater fishes. Based on these insights, the researchers ultimately aim to predict which aquatic species are at risk due to changes in their habitat caused by global warming and human activities. The study will be published in the journal Global Change Biology on 25 July.

Declining dissolved oxygen levels represent a major problem for fish and other aquatic organisms. Oxygen levels decline because the water is heating up due to climate change and because it is becoming more polluted. General biological rules can tell us which fish attributes are beneficial or detrimental when environmental conditions change. "Once we have identified these rules for fish,” says researcher Wilco Verberk, "we can ultimately predict which fish species are most at risk from environmental change."

Large and small cells

There is a lively debate among biologists on the role of oxygen in the sensitivity of fish to water subject to warming. "Many oxygen hypotheses are being fiercely debated. The problem is that the various effects are lumped together. For example, some studies look at how fish respond to oxygen levels in the water but do not account for the temperature of the water or the size of the fish. As a result, the reported patterns are variable," Verberk explains.

Verberk and colleagues have systematically separated the various effects and compiled data on tolerance to deficiency oxygen from 195 fishes to resolve this discussion. When analysing the data, they saw that larger fishes are more sensitive to oxygen stress, but only in warm water. When the water is cold, the effect is reversed.

The researchers saw a similar effect for fish that have relatively large cells. "Many people think that all animal species have the same cell size, but some animals have large cells, and some have small cells, even within the same species. There are many advantages to having small cells, especially in warm water. For example, small cells have relatively more membrane area, which is needed to absorb oxygen from their surrounding environment.”

Fresh water and saltwater

In addition, the researchers found differences between freshwater fish and marine fish. "Far too often, scientific studies only compare marine and terrestrial life. Indeed, freshwater species are sometimes lumped with terrestrial species. It is a missed opportunity because taking these differences into account can greatly increase our understanding of the environmental impacts of climate change."

According to the study by Verberk and colleagues, freshwater fishes appear to be more tolerant of oxygen-depleted water than marine fishes. "The explanation probably involves different selection pressures on freshwater fish during their evolutionary history. In the ocean, the temperature is relatively stable, but in fresh water the fish are more often confronted with higher temperatures. Fluctuations in oxygen levels are also larger in rivers and especially in lakes, for example, due to the presence of algae."

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JOURNAL

Global Change Biology

DOI

10.1111/GCB.16319 

ARTICLE TITLE

Body mass and cell size shape the tolerance of fishes to low oxygen in a temperature-dependent manner

ARTICLE PUBLICATION DATE

25-Jul-2022

Disclaimer: AAAS

Effects of lead poisoning may be reversible with early-childhood enrichment

New research shows that the majority of gene changes in the brain caused by lead can be reversed by raising animals in stimulating environments.

Peer-Reviewed Publication

THOMAS JEFFERSON UNIVERSITY

PHILADELPHIA -- Lead exposure in early childhood can lead to severe cognitive and behavioral impairments in children that last well into adolescence and adulthood. Although researchers have looked at effects of early life lead exposure on a small number of genes involved in learning, memory, and brain development, research was lacking as to the full extent of the toxicity.  New research from Thomas Jefferson University shows that over 3,500 genes in the hippocampus, a part of the brain involved in learning and memory are affected by lead poisoning. The work also shows that providing animals with stimulating environments early in life can reverse the large majority of these genetic changes, reinforcing the potentially important role of early-childhood education in combating the effects of lead poisoning.

“Children who live in housing stock built before 1978, the year in which lead was banned as an ingredient in paint, are at high risk of being exposed to lead from lead dust or chipping and peeling lead-containing paint in their homes,” says senior author Jay Schneider, PhD, professor of Pathology, Anatomy and Cell Biology at Thomas Jefferson University. “Recent estimates suggest that there are at least a half million children in the U.S. with blood lead levels at or above amounts that can adversely affect cognitive function. Our work demonstrates that by providing an enriched early life environment, the adverse effects of lead on the brain may be minimized or potentially reversed, emphasizing how important early childhood interventions may be.”

Together with lead author Garima Singh, PhD, a research assistant professor in the department of Pathology, Anatomy and Cell Biology and colleagues, the authors looked at rats that were exposed to lead from birth to the time of weaning, at 21 days of age. “Our experiments aimed to replicate conditions of human lead exposure,” says Dr. Singh. “21 days of age for rats is the equivalent to an age of about 2-3 years in humans, which is commonly when lead exposure occurs. That is because crawlers and toddlers are likely to put many things in their mouths including paint chips or toys covered in dust from deteriorating lead paint.”

From 21 days, the lead-exposed animals were separated into two different housing conditions:  ones that were either enriched or ones that lacked stimulation. The so-called enriched cages had more social activity, with a total of 6 rats, together with chew toys and various things to climb on and burrow through that were changed twice every week for novelty. The non-enriched cages were smaller, only held 3 animals and did not contain any additional stimulation. “We now know that stimulating social environments are as important for rodents as they are for human children, in terms of cognitive and behavioral health and with effects on physical health as well,” says Dr. Singh.

The researchers looked at changes in expression of genes from the part of the brain involved in memory – the hippocampal region. They found that the expression levels of over 3,500 genes were affected by the lead exposure, either abnormally churning out more or less of their gene products.  “These data show for the first time that at a genome-wide level, a large number of hippocampal genes involved in various biological processes and functions are affected by lead exposure and further modified by an enriched environment,” says Dr. Schneider. In rats exposed to lead, the genes affected were amongst those involved in memory and nerve signaling pathways, and also those involved in brain development.

However, approximately 80% of the gene expression changes induced by the lead exposure were reversed in the group of animals that lived in the stimulating environment until day 55, which is roughly equivalent to adolescence in humans. Additionally, the animals living in the non-enriched environment had memory deficits while the animals living in the enriched environment did not.

“We know that there is no safe level of lead exposure for children,” says Dr. Schneider. “Lead can damage the brain and derail normal brain development. However, our work suggests that it may be possible to mitigate the wide-spread adverse effects of lead on the young brain by providing adequate access to stimulating, interesting environments and activities in early childhood and perhaps longer. Unfortunately, these kinds of resources are often not available to the population most at risk for lead poisoning, that is, children who are growing up in impoverished or low socioeconomic environments.”  Drs. Schneider and Singh agree that although more research needs to be done in this area, the importance of early intervention programs with environmental enrichment cannot be overstated.

This research was supported by NIH grant R01ES030742. Bioinformatics support was provided in part from the Center of Excellence in Environmental Toxicology (CEET), University of Pennsylvania, Center Grant. The authors report no competing interests.

Article reference: G. Singh, V. Singh, T. Kim, A. Ertel, W. Fu and J.S. Schneider, “Altered Genome-Wide Hippocampal Gene Expression Profiles Following Early Life Lead Exposure and their Potential for Reversal by Environmental Enrichment,” Scientific Reports, 2022.

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JOURNAL

Scientific Reports

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Altered Genome-Wide Hippocampal Gene Expression Profiles Following Early Life Lead Exposure and their Potential for Reversal by Environmental Enrichment

ARTICLE PUBLICATION DATE

25-Jul-2022

Bacterial community signatures reveal how cities urbanize water sources

Peer-Reviewed Publication

LEIBNIZ INSTITUTE FOR ZOO AND WILDLIFE RESEARCH (IZW)

 

IMAGE: STECHLINSEE view more 

CREDIT: SOLVIN ZANKL/IGB

Bacterial communities are often well adapted and stable in a particular environment whether it be a human mouth or a lake. Humans are altering environments at an increasing rate, none more so than in cities and their surroundings in the process of urbanization. In a study published today in the journal “Science of the Total Environment“, led by scientists from the Leibniz Institute for Freshwater Ecology and Inland Fisheries (IGB) and the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) as part of the Leibniz Research Alliance “Infections”, bacterial communities were examined in urban water bodies and wastewater in Berlin and compared to less anthropogenically influenced lakes from surrounding rural regions. The results reveal that urbanization introduces large amounts of nutrients, chemical pollutants and antimicrobial products, and thereby changes the makeup of the microbiome by favouring groups of bacteria that contain human pathogenic bacteria, with yet unknown consequences for ecosystem functioning and human and animal health.

Whether an armpit, garden soil or water, almost every place on earth has its own natural bacterial community. By altering environments, humans also change the bacterial composition of such places by creating new conditions that favour some groups of bacteria over others. In a new study, scientists from IGB and Leibniz-IZW along with colleagues from other members of the Leibniz Research Alliance tracked these changes in bacterial composition connected with the process of urbanization and demonstrated that bacterial communities in urban waterbodies and wastewater in Berlin are distinctly different from those of rural lakes in surrounding regions in the federal states of Brandenburg and Mecklenburg-Vorpommern. The process of urbanization does not only introduce human bacteria (“humanisation”) but can also introduce excessive amounts of nutrients (“eutrophication”), chemical pollutants and antimicrobial products such as antibiotics, which can drastically favour specific bacteria over others and change the makeup of the microbiome with yet unknown consequences for ecosystem functioning and human and animal health. 

“We wanted to know whether urban water shows signatures of urbanization that are predictive of the types of bacteria present in a given community within the city limits,” says Prof Hans Peter Grossart of the IGB, co-principle investigator of the study. The results demonstrate that multiple bacterial groups are enriched in urban waters, the most extreme examples being found in the inflows and outflows of a wastewater treatment plant, pointing to a “humanisation” of urban lake microbiomes.

“Surprisingly, the enriched bacterial groups in urban environments are those that often contain pathogenic species. This suggests that if a pathogen gets into such an environment, it will find a very supportive environment in which to grow,” says Prof Alex Greenwood, head of the Leibniz-IZW Department of Wildlife Diseases and co-principle investigator of the study. This could potentially lead to outbreaks in such environments compared to rural water bodies, where such favourable conditions for pathogens were not found in general. 

In the future, water hygiene may have to consider de-urbanizing the microbiomes of city water sources to establish more natural water ecosystems within the city. This will become increasingly challenging and important as climate change makes many urban areas dryer and more nutrient rich, further altering the bacterial communities of urbanized water. This may have profound effects for human and animal health as the risk of contamination with harmful microbes increases.

Press Contact

Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) in the Forschungsverbund Berlin e.V.
Müggelseedamm 310, 12587 Berlin, Germany

Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) in the Forschungsverbund Berlin e.V.
Alfred-Kowalke-Straße 17, 10315 Berlin, Germany

JOURNAL

Science of The Total Environment

DOI

10.1016/j.scitotenv.2022.157321 

METHOD OF RESEARCH

Meta-analysis

ARTICLE TITLE

Urbanization promotes specific bacteria in freshwater microbiomes including potential pathogens.

ARTICLE PUBLICATION DATE

15-Jul-2022