TAU Researchers Found the Cause of Sea Urchin Deaths in the Red Sea, Potentially Threatening Coral Reefs Worldwide.
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Research
May 22nd, 2024
Global Coral Crisis: Deadly Sea Urchin Disease Discovered
- Life Sciences
A continuing study from TAU found that the deadly epidemic discovered last year, which has essentially wiped out Eilat's most abundant and ecologically significant sea urchins, has spread across the Red Sea and into the Indian Ocean. According to the researchers, what appeared to be a severe but local epidemic has quickly spread through the region and now threatens to become a global pandemic.
Sea urchin mortalities on Reunion Island. Photo credit: Jean-Pascal Quod.
The researchers estimate that since it broke out in December 2022, the epidemic has annihilated most of the sea urchin populations (of the species affected by the disease) in the Red Sea, as well as an unknown number of sea urchins, estimated at hundreds of thousands, worldwide. Sea urchins are considered the 'gardeners' of coral reefs, feeding on the algae that compete with the corals for sunshine – and their disappearance can severely impact the delicate balance on coral reefs globally. The researchers note that since the discovery of the epidemic in Eilat's coral reefs, the two species of sea urchins previously most dominant in the Gulf of Eilat have vanished completely.
The Research Team. Photo credit: Tel Aviv University.
The study was led by Dr. Omri Bronstein from the School of Zoology and the Steinhardt Museum of Natural History (SMNH), together with research students Lachan Roth, Gal Eviatar, Lisa Schmidt, and May Bonomo, as well as Dr. Tamar Feldstein-Farkash from the SMNH. Research partners throughout the region and Europe also took part in the study, which encompassed thousands of kilometers of coral reefs. The alarming results were published in the leading scientific journal Current Biology.
Deadly Urchin Pathogen Found
By using molecular-genetic tools, the research group at TAU was able to identify the pathogen responsible for the mass mortality of sea urchins of the species Diadema setosum in the Red Sea: a scuticociliate parasite most similar to Philaster apodigitiformis. The researchers explain that this unicellular organism was also responsible for the reoccurring mass mortality of Diadema antillarum in the Caribbeans about two years ago, following the notorious 1983 sea urchin population collapse there which led to a catastrophic phase shift of the coral reef.
Infected sea urchin on Reunion Island. Photo credit: Jean-Pascal Quod.
As noted, in December 2022, Dr. Bronstein was the first researcher to identify mass mortality of sea urchins of the species Diadema setosum – the long-spined black sea urchins that were very common in the northern Gulf of Eilat, Jordan, and Sinai. Dr. Bronstein and his team also found that the epidemic was lethal for other, closely related sea urchins from the genus Echinothrix. These results suggest that the once most abundant and significant seabed herbivores in the region are now practically gone. Thousands of sea urchins died a quick and violent death – within two days a healthy sea urchin turned into a bear skeleton with no tissues or spines, and most were devoured by predators as they were dying, unable to defend themselves. According to estimates, today only a few individuals of the affected sea urchin species remain throughout the coral reefs of the Gulf of Aqaba.
The sea urchin Diadema setosum before (left) and after (right) mortality. The white skeleton is exposed following tissue disintegration and loss of spines. Photo credit: Tel Aviv University.
Dr. Bronstein explains that sea urchins in general, and specifically diadematoids (the sea urchin family affected by the disease), are considered key species essential for the healthy functioning of coral reefs. Acting as the reef's 'gardeners', the sea urchins feed on the algae that compete with the corals for sunshine, and prevent them from taking over and suffocating the corals.
According to Dr. Bronstein, the most significant and widely studied mass mortality of sea urchins to date occurred in 1983, when a mysterious disease spread through the Caribbeans, killing most sea urchins of the species Diadema antillarum – relatives of Eilat's sea urchins. Consequently, the algae spread uncontrollably, blocking the sunlight from the corals, and the entire reef was transformed from a coral reef into an algae field. Moreover, even though the mass mortality event in the Caribbeans occurred 40 years ago, both the corals and the sea urchin populations never fully recovered, with repeated mortality events observed through the years.
The latest Caribbean outbreak in 2022 killed surviving populations and individuals from the former mortality events. This time, however, researchers had the scientific and technological tools to decipher the forensic evidence. A research group from Cornell University was able to identify the responsible pathogen, a scuticociliate parasite.
'A Growing Ecological Crisis'
Dr. Bronstein emphasizes: "This is a growing ecological crisis, threatening the stability of coral reefs on an unprecedented scale. Apparently, the mass mortality we identified in Eilat back in 2023 has spread along the Red Sea and beyond - to Oman, and even as far as Reunion Island in the Indian Ocean.
The deadly pathogen is carried by water and can affect vast areas in a very short time. Even sea urchins raised in seawater systems at the Interuniversity Institute for Marine Sciences in Eilat, or at the Underwater Observatory, were infected and died, after the pathogen got in through the recirculating seawater system. As noted, death is quick and violent. For the first time, our research team was able to document all stages of the disease – from infection to the inevitable death – with a unique video system installed at the Interuniversity Institute for Marine Sciences in Eilat.
Moreover, until recently, only one species of sea urchins was known to be impacted by this pathogen – the Caribbean species. Today we know that additional species are susceptible to the disease – all belonging to the same family of the most significant sea urchin herbivores on coral reefs".
Four healthy sea urchin species on Reunion Island. Photo credit: Jean-Pascal Quod.
Dr. Bronstein adds: "In our study we also demonstrated that the epidemic is spreading along routes of human transportation in the Red Sea. The best example is the wharf in Nueiba in Sinai, where the ferry from the Jordanian city of Aqaba docks. When we published our report last year, we already knew of sea urchin mortalities in Aqaba but had not yet identified signs of it in Sinai. The first spot in which we ultimately did identify mortality in Sinai was next to this wharf in Nueiba. Two weeks later the epidemic had already reached Dahab, about 70km further south. The scene underwater is almost surreal: seeing a species that was so dominant in a certain environment simply erased in a matter of days. Thousands of skeletons rolling on the sea bottom, crumbling and vanishing in a very short time so that even evidence for what has occurred is hard to find".
Can We Stop the Sea Urchin Plague?
According to Dr. Bronstein, there is currently no way to help infected sea urchins or vaccinate them against the disease. We must, however, quickly establish broodstock populations of endangered species in cultivation systems disconnected from the sea – so that in the future we will be able to reintroduce them into the natural environment.
"Unfortunately, we cannot repair nature, but we can certainly change our own behavior. First of all, we must understand what caused this outbreak at this time. Is the pathogen transported unknowingly by seacraft? Or has it always been here, erupting now due to a change in environmental conditions? These are precisely the questions we are working on now".
Research
May 21st, 2024
Wake-Up Call: Global Warming and Deforestation Threaten Wildlife
A New TAU Study Shows that Global Warming and Deforestation Could Cause Mass Animal Extinctions.
- Life Sciences
A joint study by TAU and the University of Colorado (CU) states that the combination of global warming and extreme heat events, alongside the continued expansion of deforestation in the world, may be devastating for many species of animals, especially those that know how to climb trees. As part of the study, the researchers focused on lizards and showed that following the effects of climate change, they will seek refuge from the hot ground by spending a lot of time on trees. However, due to human-related activities, such as deforestation, urbanization and the expansion of agricultural lands at the expense of natural lands, the availability of trees in the areas where the lizards live will decrease, and this may lead to the collapse of many populations.
The research was conducted under the leadership of doctoral student Omer Zlotnick from the laboratory of Dr. Ofir Levy at the School of Zoology, the Wise Faculty of Life Sciences and the Steinhardt Museum of Natural History at TAU and in collaboration with Dr. Keith Musselman from CU. The study was published in the journal Nature Climate Change.
Climate Crisis: Animals Seeking Comfort in Trees
The researchers explain that the climate crisis and global warming force animals to search for more comfortable places to stay to escape the extreme heat, just as we look for a shady area on a hot day. For climbing animals, trees can serve as a comfortable and pleasant refuge. One of the reasons for this is that the farther you get from the ground, the lower the air temperature gets, and the stronger the wind becomes. Therefore, on hot days, for example, animals can climb up trees to escape from the hot ground.
The importance of trees, then, is expected to increase as the climate warms. The problem is that in many places in the world, the density of trees is decreasing, mainly due to phenomena such as deforestation and the expansion of the use of trees for various purposes such as construction, etc. This phenomenon creates a situation where, on the one hand, due to climate change, animals will depend more on trees for their survival, while on the other hand, the destruction of habitats will lead to a decrease in the availability of trees.
Lizards' Habitat Loss
Doctoral student Omer Zlotnik: "As part of the research, we wanted to examine how the combined effect of these two processes would be on animals. Specifically, we focused on lizards because they are very dependent on their environment to maintain a normal body temperature, and a lack of comfortable places to stay can affect them dramatically. In the study, we used a computer simulation to simulate where the lizard should be, in the sun, in the shade, or on the tree, every minute for 20 years, under the climate conditions that existed in the past and under those expected in the future. Using the simulation, we examined how populations of lizards would be affected by climate change when trees are available and how their situation would change following the felling of trees in their habitat".
Left to right - Dr. Ofir Levy & Omer Zlotnick
The results showed that, in general terms, climate change is going to benefit many lizard populations. In most places, the expected warming will allow lizards to be active longer throughout the day and the year, as there will be fewer times when it is too cold to come out of their burrows. However, when climate change occurs at the same time as the felling of trees, the trend is likely to reverse, so that many lizard populations may collapse. In areas with a warm climate, climate change, even if no trees are cut down, is expected to harm lizard populations, and cutting down trees will make the situation even worse.
"What's really interesting about lizards is that they just need to be able to move a short distance around the tree trunk to get to a very different climate and habitat environment", said Keith Musselman, an assistant professor in the Department of Geography and CU Boulder’s Institute of Arctic and Alpine Research.
Musselman: "These microhabitats are particularly important when we think about how we modify our natural environment and make conservation decisions".
Dr. Ofir Levy concludes: “Our research focused on lizards, but it actually demonstrates a broader problem that is relevant to many species of animals. Our results demonstrate that trees are crucially important to the ability of animals to cope with climate change, and in many cases, their availability can be, for the animals, the difference between crawling and collapsing. Our research proves how important it is to preserve forested areas and trees in general, especially in light of the changing climate. As part of the research, we also provide more practical tools for decision-makers, such as the height or density of trees required in different areas. We hope that this research will be used to build more effective programs for the conservation and restoration of natural areas so that we can provide the animals with what they need to survive".
Research
May 19th, 2024
Will Existing Drugs Stop Cancer's Bone Spread?
Existing Meds May Prevent Bone Spread in Breast Cancer Patients
- Medicine
Researchers at TAU developed a new therapeutic strategy based on existing medications to inhibit bone metastasis in breast cancer patients. Using both an animal model and tissue samples from patients in Israel and the US, they demonstrated that a combination of drugs already available on the market can hinder bone metastasis and improve survival. Based on their findings, the researchers predict that in the future, the treatment can apply to human patients with breast cancer, as well as other types of cancer.
The groundbreaking study was led by Prof. Neta Erez and Dr. Lea Monteran at Prof. Erez's Laboratory for Tumor Biology at the Pathology Department, Faculty of Medical and Health Sciences, Tel Aviv University. The paper was published in Cancer Discovery. The researchers explain that over 75% of patients with metastatic breast cancer suffer from bone metastases, which destroy bone tissues, causing fractures and a great deal of pain. Moreover, with today's technologies such as MRI or CT imaging, diagnosis of bone metastasis occurs, in most cases, when the disease cannot be cured. In this study, the researchers looked for a novel way to inhibit the progression of bone metastasis.
Cancer Cell Sabotage
Prof. Erez, Kadar Family Award for Outstanding Research recipient: "A tumor is more than a collection of cancer cells. Just like healthy tissues, a tumor is a whole ecosystem consisting of reciprocal interactions between different cell types, including cells of the immune system, connective tissues, blood vessels, etc. Moreover, cancer cells often 'corrupt' normal cells, causing them to 'collaborate' with the tumor and support the growth of cancer cells. Blocking the communication channels between cancer cells and healthy cells at an early stage can hinder the growth of cancer cells in the bones. To achieve this, the early stages of the process must be investigated". To understand processes of bone metastasis the researchers compared three types of bones from model mice: healthy, early-stage metastasis, and advanced metastasis. They found that when bone metastasis begins, T cells from the immune system arrive on the scene and penetrate the metastases but are unable to destroy them.
Prof. Neta Erez
Next, the researchers discovered that the killing activity of T cells is inhibited by another type of immune cells and identified the proteins responsible for this effect. To neutralize these inhibitory proteins and reactivate the T-cells, they created a novel therapeutic combination that has never been tried before a drug that counters the activity of the immune-inhibiting cells, along with an antibody that activates T cells. This combination was administered to model mice, and the results were encouraging: the bone metastases were reduced, and survival was significantly improved compared to untreated model mice.
At the final stage of the study, the TAU research team collaborated with the Sheba and Ichilov (Tel Aviv) Medical Centers and the Baylor College of Medicine in Texas. They examined tissue samples from bone metastases taken from patients with breast cancer, as well as other types of cancer, and found that the immune cells inhibiting T cells express the same proteins as those found in the animal model. Prof. Erez: "Our findings suggest that the combined treatment – attacking the cells that inhibit T cells while activating the T cells – can be effective for treating bone metastasis resulting from breast cancer as well as other types of cancer. The great advantage of our strategy is that both drugs are already available on the market and consequently, the process of obtaining permits to use them against bone metastasis in humans can be relatively short. At the same time, clinical trials need to verify the effectiveness of the new therapeutic strategy".
The study was funded by the Israel Cancer Research Fund (ICRF), the Israel Science Foundation (ISF), Worldwide Cancer Research (WWCR), and the U.S. Department of Defense (DoD).
Research
May 16th, 2024
How Do Lightning Storms Affect North Pole Sea Ice?
TAU Research Shows that Lightning Storms are Causing Sea Ice to Melt Faster at the North Pole
- Environment
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".
