Tag: Environment

A new TAU study shows that early-life experiences — more than innate personality — shape how bats behave in the wild.

A new study from Tel Aviv University’s School of Zoology reveals that the environment in which a bat is raised during the first months of its life largely determines how it will behave in the wild,  sometimes even more than its innate personality.

The study, led by doctoral student Adi Rachum from the laboratory of Prof. Yossi Yovel at the School of Zoology, Wise Faculty of Life Sciences, and the Sagol School of Neuroscience, was published in the journal eLife.

Growing Up in Two Different Worlds

The research investigated for the first time how early exposure to a variable and challenging environment affects the behavior of Egyptian fruit bats after they are released into the wild. The researchers raised 40 young bats in two completely different environments: one enriched and dynamic, in which the bats had to cope with new challenges every day in order to obtain food; and the other stable and unchanging. After a period of several months, their behavior in the wild was monitored using GPS devices that tracked their every flight.

The findings were clear and consistent: bats raised in the enriched environment exhibited much bolder and more exploratory behavior in the wild. They flew farther away from “home,” spent more time out foraging at night, and explored areas almost twice as large as those explored by the control group.

For example, bats raised in the enriched environment explored average foraging areas of approximately eight square kilometers, compared to only about three square kilometers among bats raised in the impoverished environment. The maximum distance they ventured from the colony was also notably greater — an average of about 1.3 kilometers versus only 0.8 kilometers in the comparison group. In addition, they spent an average of roughly four hours outside the colony each night, compared with less than three hours among bats in the control group.

Not Personality — Experience

To ensure that the differences did not stem from variations in the bats’ innate personality, the researchers assessed the young bats’ personality traits in the laboratory before they were exposed to the different environments. They found that these traits did not predict the bats’ behavior in the wild as adults. In other words, the bats’ innate disposition did not account for their later differences in behavior in the wild. Instead, the environment in which they were raised during their early life proved to be the decisive factor shaping how they behaved as adults.

Adi Rachum explains: “Fruit bats are animals with remarkable behavioral flexibility and learning capacity. We found that the early environment to which bats are exposed influences the way they explore the world.”

Prof. Yossi Yovel adds: “In previous studies, we identified behavioral differences between exploratory urban bats and more ‘conservative’ rural bats. The current findings may explain how these differences between the groups are formed.”

Prof. Yossi Yovel

*Prof. Yossi Yovel is a world-renowned Israeli researcher and a senior faculty member at the School of Zoology and the Sagol School of Neuroscience. He leads the field of neuroecology, which combines brain research and ecology to understand how animals make decisions and navigate in their natural environment. Considered a leading expert on bats, he studies their sonar system (echolocation), social communication, and remarkable navigation abilities.

Researchers warn that patterns seen in the Canary Islands may emerge in other regions worldwide.

A global study by an international research team, including Prof. Omri Bronstein of the School of Zoology, Wise Faculty of Life Sciences and the Steinhardt Museum of Natural History at Tel Aviv University – who is leading global efforts to study the wave of sea urchins mass mortalities around the world, presents new and particularly alarming findings: for the first time, evidence of apparent local sea urchin extinction has been found in the Canary Islands.

The study revealed that the genus Diadema (the long-spined black sea urchins many of us are familiar with) is no longer able to produce offspring at this site — a finding that likely indicates local extinction.

The study was carried out by an international consortium including Tel Aviv University scientists in collaboration with researchers from Spain and the Canary Islands. The findings were published in the journal Frontiers in Marine Science.

From Local Die-Offs to Global Spread

Prof. Bronstein describes the sequence of events over recent decades: “In 1983–84, a mass mortality event of Diadema sea urchins was recorded in the Caribbean islands in the western Atlantic Ocean. This die-off triggered a dramatic ecological shift in the region: with the sea urchins — the habitat’s primary algae grazers — gone, vast algal fields spread, blocking sunlight and causing severe, irreversible damage to coral reefs in the region. In 2022, another mortality event struck the Caribbean, and for the first time the pathogen responsible for the lethal disease was identified. This epidemic spread to the Red Sea by 2023, and by 2024 it was also detected in the Western Indian Ocean, off the coast of Reunion.”

The Canary Islands: A Missing Link

In the current study, a formerly undetected mass mortality event was identified in the Canary Islands, off the coast of Morocco in the eastern Atlantic Ocean, which in fact occurred as early as mid-2022. According to the researchers, this event represents the “missing link” in the disease’s geographic spread. The study also revealed a particularly troubling finding, which likely points to the potential local extinction of the species in the Canary Islands. The study was based on extensive observational data collected through local citizen science, alongside scientific surveys, satellite data analysis (remote sensing), and the collection of samples from the seafloor by the research team.

Prof. Bronstein explains: “Sea urchins reproduce by releasing sperm and eggs into the seawater, where fertilization produces millions of embryos that drift as plankton in the water column. After several days to weeks (depending on the species), the larvae settle on the seabed and develop into juvenile urchins — a process known as ‘recruitment.’ In this study, we discovered that for the first time in history, there are no new juvenile urchins being recruited across several Canary Islands, indicating that the recruitment process has halted since the extensive mortality event that took place there. In other words, the die-off of the adult urchins has been so widespread that the species is no longer able to produce a next generation, if no recruitment occurs, the species may disappear from the region’s ecosystem.”

 Prof. Omri Bronstein

A Warning for Other Marine Ecosystems

The researchers note that sea urchin populations are typically characterized by fluctuations — they often decline and later recover. This time, however, the situation is far more severe and appears to be an extinction event rather than a transitional phase. The researchers warn that the pattern observed in the Canary Islands may also unfold in other regions around the world where unprecedented sea urchin mass mortality events have been recorded in recent years — including the Red Sea coast and the coral reef of the Gulf of Eilat.

Prof. Bronstein concludes: “In this study, we identified a mass mortality event of sea urchins that occurred in mid-2022 in the Canary Islands. In its aftermath, it became clear that the affected species is no longer capable of successfully reproducing in this area — a finding that may lead to local extinction, which is expected to have severe ecological consequences. A likely outcome would be the uncontrolled proliferation of algae, which would affect the entire ecosystem — although at this stage, it is difficult to predict exactly in what way.

Marine animals eat and release microplastics, harming the environment.

A new Tel Aviv University study has uncovered alarming findings about the spread of microplastic particles in the marine food web. In recent years, numerous studies have examined the dangers of aquatic animals and more specifically, filter-feeding organisms, ingesting non-degradable microplastic particles. In the current study, the research team sought to understand how the biological filtration by filter-feeding organisms affects the microplastics in their environment. The findings indicate that the particles are excreted in the feces of marine animals, causing them to be unidentifiable as plastic to the aquatic environment, but potentially as other organic matter suitable for consumption.

Additionally, the presence of microplastic within feces affects the feces dispersal which causes accumulation of feces and plastic particles. This may increase carbon and nitrogen levels on the seafloor and lead to algal blooms, which have a critical impact on the balance of the marine food web.

The research was conducted by PhD student Eden Harel of the School of Zoology in the Wise Faculty of Life Sciences, Prof. Noa Shenkar of the School of Zoologyand the Steinhardt Museum of Natural History, and Prof. Ines Zucker of the School of Mechanical Engineering and the Porter School of Environment and Earth Sciences, all at Tel Aviv University. The study was published in the journal Chemosphere.

 Prof. Shenkar during a research dive (Photo credit: Dr. Tom Shlesinger).

Prof. Shenkar explains: “About a decade ago, when awareness of the plastic pollution problem in the marine environment began to grow, many researchers focused on identifying the location and scale of microplastic particles. Recently, the research focus has shifted to the effects and damage caused by microplastics. However, many experiments in this field are conducted using clean, purchased plastic, whereas in the sea, plastic particles are exposed to a wide range of influences and pollutants. We aimed to examine whether and how plastic changes after passing through the digestive system of a marine organism and how this process affects the presence of plastic and its availability to other organisms”.

How Marine Organisms Process Microplastics

The researchers created an experimental system in the lab simulating seawater containing ascidians — marine animals that feed by efficiently and indiscriminately filtering tiny particles from the water. They exposed the ascidians to two types of plastic particles: conventional polystyrene (PS), which is widely used, and polylactic acid (PLA), marketed as a biodegradable, environmentally friendly bioplastic. They then examined the impact of the ascidians’ filtration process on the concentration and distribution of plastic particles in the water at four intervals: at the time of exposure, after two hours (when the ascidians had filtered all available water and ingested the microplastic particles), after 24 hours, and after 48 hours (following digestion and the excretion of feces into the water).

The laboratory at Tel Aviv University where the experiment was conducted (Photo credit: Eden Harel).

The findings showed that approximately 90% of the polystyrene particles were removed from the water after two hours of filtration, but all the particles returned to the water after 48 hours, following passage through the digestive system. In contrast, the concentration of PLA particles in the water significantly decreased and remained low for 48 hours, larger PLA particles likely broke down during digestion and returned to the water as smaller undetectable nano-sized particles.

In the second phase of the study, the researchers examined what had happened to the microplastic particles that were filtered, digested, and excreted back into the water column. To do so, they isolated microplastic particles from the ascidians’ feces and analyzed them using Raman spectroscopy, an advanced device that identifies the chemical composition of materials by scattering a laser beam.

Eden Harel explains: “We found that the sensitive spectroscopy device could not identify the material as plastic at all and instead identified the particle as another type of organic material. Our findings revealed that microplastic particles are excreted from the ascidian’s digestive system coated with a fecal layer, and it is likely that the marine environment also identifies these particles as this organic material. Since many marine animals feed on feces, they may well ingest plastic that has changed its properties, identifying it as food. In this way, they are also exposed to microplastics and spread them further within the marine food web. The fecal coating may serve as a substrate for bacterial colonization and increase the adhesion and accumulation of pollutants such as heavy metals and residual organic substances (like antibiotics) on the plastic particles”.

Prof. Zucker adds: “This phenomenon also affects bioplastics marketed as ‘biodegradable’: unless conditions are met for their complete breakdown, they remain as particle pollution that changes properties during passage through the digestive system. The many transformations plastic particles undergo in the environment — from weathering to digestive processes, as investigated in this study — turn them into carriers of pollutants and diseases within the food web”.

 The researchers analyzing the secretions of marine animals (Photo credit: Eden Harel).

What’s the Impact of Microplastics on Marine Life?

In the third phase of the study, the researchers examined the reverse effect: how microplastic particles affect feces, an organic material that plays a vital role in marine ecology. Eden Harel explains: “We found that plastic changes important physical properties of feces. Normal feces sink very slowly through the water column, serving as food for many organisms along the way. In contrast, feces containing microplastic particles sink rapidly to the seafloor. This removes an important nutrient source from the water column. Additionally, the faster sinking rate decreased the dispersion of the feces causing accumulation of feces and plastic particles near where the animals are settled. This accumulation can increase carbon and nitrogen levels on the seafloor and trigger algal blooms, representing another critical impact of microplastics on the balance of the marine food web”.

The researchers conclude: “In this study, we uncovered significant aspects of the influence of filter-feeding animals on the characteristics of microplastic particles in their environment and within the marine food web. The most alarming conclusion is that the microplastic problem is far more complex than initially thought. Plastic pollution in the marine environment has many unexpected dimensions, and its complexities continue to grow. Sometimes, neither we nor the environment can even recognize it as plastic. As time goes on, plastic continues to harm more and more marine ecosystems. We must develop new technologies to mitigate this dangerous phenomenon”.

10 different pharmaceuticals detected in corals in the Gulf of Eilat.

TAU post-doc Tamar Elman is creating a startup to harness hydrogen gas produced by algae during photosynthesis.

Recent reports that 2023 was the world’s hottest year on record highlights the urgency of mitigating climate change. One unavoidable change will be to clean up the energy sector, which currently produces 70% of industrial waste including greenhouse gases and ozone-eroding chemicals. The solution may come in the form of a tiny single-celled organism which most may recognize as the green layer on top of lakes and ponds: algae. Tamar Elman, a Tel Aviv University post-doctoral researcher in the lab of Iftach Yacoby at the Wise Faculty of Life Science, has discovered a microalgae species with a mutation which produces large amounts of hydrogen gas, a promising clean energy source. After completing a course at TAU’s Entrepreneurship Center, she is building a startup to figure out how this hydrogen production might be harnessed and industrialized.  

An Accidental Discovery  

Hydrogen gas is a very clean source of energy because its only byproduct is water vapor. “Unfortunately,” says Elman, “because it does not naturally accumulate anywhere in large amounts, producing hydrogen gas in a usable form does produce carbon waste. So there is a race right now to create a totally green production method that is also scalable and profitable.” 

“There is a race right now to create a totally green production method that is also scalable and profitable.”

One natural source of hydrogen gas is microalgae, which is found in most habitats around the world and grows easily. In 2021, Elman was trying to increase the small amounts of hydrogen gas produced by microalgae in the TAU Yacoby lab. “Microalgae are considered plants because they perform photosynthesis, using solar energy to transform carbon dioxide into sugars for nourishment. However, green algae also have a built-in “circuit breaker” that burns off any excess solar energy by converting it to hydrogen gas. Unfortunately, hydrogen production is usually shut down quickly by other functions of the algae.  

One day, Elman and Prof. Yacoby tested a new culture and saw the hydrogen levels reaching unprecedented heights. “We thought we were seeing a mistake in the hydrogen measuring device. We almost threw out the culture!” Says Elman. “But when we tried it on a different device and got the same results, we realized we had found a mutated algae strain that naturally overcame the barriers to continued hydrogen gas production.” 

Scaling Up 

Upon publishing a paper in 2022 on their discovery, Elman and Prof. Yacoby garnered quite a bit of interest from the scientific community. The two decided to capitalize on the buzz, delving further into experimentation on their mutation. Elman also won a grant from the Israeli Innovation Authority which required she take a course on breaking into industry at TAU’s Entrepreneurship Center. 

Elman and Yacoby nailed down their idea to produce hydrogen gas for the energy sector and to work with the food industry to sell the used algae, which is left with high nutritional value after the production process.  

Elman and Prof. Yacoby hope to industrialize microalgae-based hydrogen gas production. (Photo: Tel Aviv University)

The two discovered that scaling up creates its own host of challenges, as processes that work at small scales may not always translate proportionally. Elman realized she would need a very simple way to induce hydrogen production in the algae. “It’s almost comical how basic this method is,” she says of her solution. “All I do is give the algae some concentrated acid and let them sit in the dark for two hours breathing oxygen. Then I open the windows to let light in, and the algae start producing hydrogen! It’s practically too simple to market, but it really works.”  

Elman spent the last year gathering her data and creating material for investors and industry stakeholders with the help of her Entrepreneurship Center team. Now, she is meeting with investors. “Even though it’s very difficult, I know I would regret not trying. And it’s an amazing feeling to see my research lead to something concrete.” 

Her next steps are, she hopes, to build a large photobioreactor that can be used for larger-scale experiments and production. 

Thinking Like an Entrepreneur 

To learn what is needed to create a startup and collaborate with industry, Elman participated in a course called JumpTAU which brought together Arab and Jewish students in mixed startup-building teams at TAU’s Entrepreneurship Center. For months, the teams received intensive lectures, individual guidance and networking opportunities from industry experts and dedicated mentors. 

“Entrepreneurship is a different type of thinking. I had to figure out who my audience was and how to frame my work as beneficial to them.”

After performing scientific research for 9 years, says Elman, “entrepreneurship is a really different type of thinking. I discovered that customers and investors aren’t interested in science for science’s sake, so I had to figure out who my audience was and how to frame my work as beneficial to them. Now a year later, I have a professional slide deck I can proudly show to investors.” 

She felt particularly supported by the mentors and Center Director Yair Sakov, all of whom she says she can still turn to for ongoing counsel. “I really feel like those at the Center care about my success.” 

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TAU Research Shows that Lightning Storms are Causing Sea Ice to Melt Faster at the North Pole

A new international study with the participation of researchers from Tel Aviv University found that alongside the general warming of the globe, lightning storms have been directly hastening the ongoing process of sea ice retreat covering the Arctic Ocean. According to the researchers: “Until recently, lightning as a phenomenon was extremely rare in the Arctic region of the North Pole, due to the intense cold. However, due to the warming of the Earth, lightning storms have become more common there in the summers, and these storms further increase the melting process of the ice sheets – in a feedback loop”.

Prof. Colin Price and MSc student Tair Plotnik from the Department of Geophysics at TAU’s Porter School of the Environment and Earth Sciences participated in the study, alongside Dr. Anirban Guha and Dr. Joydeb Saha from Tripura University in India. The article was published in the journal Atmospheric Research.

Arctic’s Cold Reality: Understanding Rapid Ice Loss

Prof. Price explains: “The Arctic region is defined as the region located north of the 66.5° latitude. In the heart of this region, around the North Pole, there is no land, and due to the extreme cold conditions, the sea is covered with a thick layer of sea ice, which currently extends over about 8 million square kilometers. The white ice reflects the sun’s rays and thus contributes to the cooling of the Earth. But in recent decades, with the warming of the Earth, the ice cover has retreated at a rate of about 70,000 square kilometers per year, or 6.5% per decade (In this context, it is important to note that the temperature at the North Pole has been rising at an accelerating pace – about 4° until today, in contrast to about 1° on Earth as a whole).

Prof. Colin Price

The retreat of the ice increases the warming even further, because the dark areas of the ocean under the ice, which are getting bigger and bigger, absorb the sun’s rays that would normally be reflected in space. This is how a feedback loop is created: the retreat of the ice increases the warming, which in turn increases the melting of the ice, and the cycle repeats”.

Lightning’s Role in Polar Ice Melt

According to the researchers, the phenomenon of melting ice sheets at both poles is firstly attributed to the result of human activity due to the increase in the amount of greenhouse gases in the atmosphere, creating a kind of ‘blanket’ that preserves the heat and does not allow it to disperse into space. However, studies have not found a direct match between the greenhouse gas changes, which increase at a more or less constant rate every year, and the rate of sea ice melting, which varies immensely from year to year. This study sought to examine the possible effect of another factor – lightning storms – on the melting of the sea ice in the Arctic region.

The researchers explain that lightning, as a phenomenon, was extremely rare in the Arctic region until recently, due to the intense cold that prevails there. But in recent decades, apparently, due to global warming, lightning storms have been observed there in the summertime, when the sun does not set at all, heating the surface (Lightning storms form when the surface of the ground heats up, and pockets of air rise in the atmosphere, where they cool, condense, and become clouds that sometimes develop into thunderstorms).

To test their hypothesis that lightning storms contribute to the melting of the ice around the North Pole, the researchers compared two sets of data: images from NASA satellites that have been documenting the retreat of the ice in the Arctic Sea for more than 40 years, and lightning data collected by the global network WWLLN (wwlln.net) – which includes around 70 lightning detection stations, deployed in research institutions all over the world – one of which stands on the roof of the Faculty of Exact Sciences building at TAU. Prof. Price explains: “Lightning is the result of a massive electric field that is discharged at once and transmits radio waves that can be received even thousands of kilometers away from the lightning. The global network’s sensors detect and map thunderstorms anywhere on the planet, in real-time and non-stop. Cross-referencing the information from the various stations allows for an accurate determination of the location and time of each lightning strike detected, and thus, a global map of lightning over time is obtained. For this study, we collected data on lightning in the Arctic region during the summer months of June, July and August every year since 2010″.

Lightning Storms: Catalysts for Polar Ice Melt

A statistical analysis of the ice sheet retreat crossed with the number of lightning storms revealed a correlation: as the number of storms increased in a certain year, so did the melting of the sea ice increase that year. The researchers explain this by comparing thunderstorms to a giant vacuum cleaner, sucking water vapor up from the surface layer to the upper atmosphere (5-10km altitude), where it accumulates and acts like an additional blanket, trapping the surface heat from leaving, and increasing the surface temperature – just like man-made greenhouse gases. Another possibility observed in a previous study is that these same lightning storms lead to an increase in the formation of high cirrus clouds in the upper layers of the atmosphere – which also form a similar ‘blanket’.

Prof. Price concludes: “In our research, we found a clear statistical relationship between the number of lightning storms in the Arctic region in a certain year and the rate of sea ice melting that year. This means that the storms are another factor that increases the melting of the polar ice, producing a feedback loop: the initial melting of the ice increases the dark surface areas of the sea, which absorb more of the sun’s rays, warming up the waters, causing more melting, accelerating the rate of warming, which in turn increases the number of lightning storms, and the cycle repeats itself. As a result of this, and of the warming of the Earth in general, we expect that the frequency of lightning storms in the Arctic region will increase in the coming years, and with it, the rate of sea ice retreat in the Arctic Sea will accelerate”.